draft-ietf-bess-evpn-prefix-advertisement-04.txt   draft-ietf-bess-evpn-prefix-advertisement-05.txt 
skipping to change at page 1, line 14 skipping to change at page 1, line 14
Internet Draft W. Henderickx Internet Draft W. Henderickx
Intended status: Standards Track Nokia Intended status: Standards Track Nokia
J. Drake J. Drake
W. Lin W. Lin
Juniper Juniper
A. Sajassi A. Sajassi
Cisco Cisco
Expires: August 17, 2017 February 13, 2017 Expires: January 19, 2018 July 18, 2017
IP Prefix Advertisement in EVPN IP Prefix Advertisement in EVPN
draft-ietf-bess-evpn-prefix-advertisement-04 draft-ietf-bess-evpn-prefix-advertisement-05
Abstract Abstract
EVPN provides a flexible control plane that allows intra-subnet EVPN provides a flexible control plane that allows intra-subnet
connectivity in an IP/MPLS and/or an NVO-based network. In NVO connectivity in an IP/MPLS and/or an NVO-based network. In some
networks, there is also a need for a dynamic and efficient inter- networks, there is also a need for a dynamic and efficient inter-
subnet connectivity across Tenant Systems and End Devices that can be subnet connectivity across Tenant Systems and End Devices that can be
physical or virtual and may not support their own routing protocols. physical or virtual and do not necessarily participate in dynamic
This document defines a new EVPN route type for the advertisement of routing protocols. This document defines a new EVPN route type for
IP Prefixes and explains some use-case examples where this new route- the advertisement of IP Prefixes and explains some use-case examples
type is used. where this new route-type is used.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
skipping to change at page 2, line 7 skipping to change at page 2, line 7
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html http://www.ietf.org/shadow.html
This Internet-Draft will expire on August 17, 2017. This Internet-Draft will expire on January 19, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction and problem statement . . . . . . . . . . . . . . 3 2. Introduction and problem statement . . . . . . . . . . . . . . 4
2.1 Inter-subnet connectivity requirements in Data Centers . . . 4 2.1 Inter-subnet connectivity requirements in Data Centers . . . 4
2.2 The requirement for a new EVPN route type . . . . . . . . . 6 2.2 The requirement for a new EVPN route type . . . . . . . . . 7
3. The BGP EVPN IP Prefix route . . . . . . . . . . . . . . . . . 8 3. The BGP EVPN IP Prefix route . . . . . . . . . . . . . . . . . 8
3.1 IP Prefix Route encoding . . . . . . . . . . . . . . . . . . 8 3.1 IP Prefix Route encoding . . . . . . . . . . . . . . . . . . 9
4. Benefits of using the EVPN IP Prefix route . . . . . . . . . . 10 3.2 Overlay Indexes and Recursive Lookup Resolution . . . . . . 10
5. IP Prefix overlay index use-cases . . . . . . . . . . . . . . . 11 4. IP Prefix Overlay Index use-cases . . . . . . . . . . . . . . . 13
5.1 TS IP address overlay index use-case . . . . . . . . . . . . 11 4.1 TS IP address Overlay Index use-case . . . . . . . . . . . . 13
5.2 Floating IP overlay index use-case . . . . . . . . . . . . . 14 4.2 Floating IP Overlay Index use-case . . . . . . . . . . . . . 15
5.3 ESI overlay index ("Bump in the wire") use-case . . . . . . 15 4.3 Bump-in-the-wire use-case . . . . . . . . . . . . . . . . . 17
5.4 IP-VRF-to-IP-VRF model . . . . . . . . . . . . . . . . . . . 18 4.4 IP-VRF-to-IP-VRF model . . . . . . . . . . . . . . . . . . . 20
5.4.1 Interface-less IP-VRF-to-IP-VRF model . . . . . . . . . 19 4.4.1 Interface-less IP-VRF-to-IP-VRF model . . . . . . . . . 21
5.4.2 Interface-full IP-VRF-to-IP-VRF with core-facing IRB . . 22 4.4.2 Interface-ful IP-VRF-to-IP-VRF with core-facing IRB . . 24
5.4.3 Interface-full IP-VRF-to-IP-VRF with unnumbered 4.4.3 Interface-ful IP-VRF-to-IP-VRF with unnumbered
core-facing IRB . . . . . . . . . . . . . . . . . . . . 24 core-facing IRB . . . . . . . . . . . . . . . . . . . . 27
6. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 27 5. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 30
7. Conventions used in this document . . . . . . . . . . . . . . . 28 6. Conventions used in this document . . . . . . . . . . . . . . . 31
8. Security Considerations . . . . . . . . . . . . . . . . . . . . 28 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 31
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 28 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 31
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 31
10.1 Normative References . . . . . . . . . . . . . . . . . . . 29 9.1 Normative References . . . . . . . . . . . . . . . . . . . . 31
10.2 Informative References . . . . . . . . . . . . . . . . . . 29 9.2 Informative References . . . . . . . . . . . . . . . . . . . 31
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 29 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 32
12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 29 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 32
13. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 29 12. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 32
1. Terminology 1. Terminology
GW IP: Gateway IP Address GW IP: Gateway IP Address.
IPL: IP address length
IRB: Integrated Routing and Bridging interface IPL: IP address length.
ML: MAC address length ML: MAC address length.
NVE: Network Virtualization Edge NVE: Network Virtualization Edge.
TS: Tenant System TS: Tenant System.
VA: Virtual Appliance VA: Virtual Appliance.
RT-2: EVPN route type 2, i.e. MAC/IP advertisement route RT-2: EVPN route type 2, i.e. MAC/IP advertisement route.
RT-5: EVPN route type 5, i.e. IP Prefix route RT-5: EVPN route type 5, i.e. IP Prefix route.
AC: Attachment Circuit AC: Attachment Circuit.
Overlay index: object used in the IP Prefix route, as described in ARP: Address Resolution Protocol.
this document. It can be an IP address in the tenant space or an ESI,
and identifies a pointer yielded by the IP route lookup at the
routing context importing the route. An overlay index always needs a
recursive route resolution on the NVE receiving the IP Prefix route,
so that the NVE knows to which egress NVE it needs to forward the
packets.
Underlay next-hop: IP address sent by BGP along with any EVPN route, ND: Neighbor Discovery Protocol.
i.e. BGP next-hop. It identifies the NVE sending the route and it is
used at the receiving NVE as the VXLAN destination VTEP or NVGRE
destination end-point.
Ethernet NVO tunnel: it refers to Network Virtualization Overlay Ethernet NVO tunnel: it refers to Network Virtualization Overlay
tunnels with Ethernet payload. Examples of this type of tunnels are tunnels with Ethernet payload. Examples of this type of tunnels
VXLAN or nvGRE. are VXLAN or nvGRE.
IP NVO tunnel: it refers to Network Virtualization Overlay tunnels IP NVO tunnel: it refers to Network Virtualization Overlay tunnels
with IP payload (no MAC header in the payload). Examples of IP NVO with IP payload (no MAC header in the payload).
tunnels are VXLAN GPE or MPLSoGRE (both with IP payload).
EVI: EVPN Instance spanning the NVE and PE devices that are
participating on that EVPN.
MAC-VRF: A Virtual Routing and Forwarding table for Media Access
Control (MAC) addresses on an NVE/PE, as per [RFC7432].
BD: Broadcast Domain. As per [RFC7432], an EVI consists of a single
or multiple BDs.
BT: Bridge Table. The instantiation of a BD in a MAC-VRF.
IP-VRF: A VPN Routing and Forwarding table for IP addresses on an
NVE/PE, similar to the VRF concept defined in [RFC4364], however,
in this document, the IP routes are always populated by the EVPN
address family.
IRB: Integrated Routing and Bridging interface. It connects an IP-VRF
to a BT. In order to simplify the explanation, this document
assumes a single BT and subnet per MAC-VRF. If the EVI consisted
of multiple BDs (a subnet per BD) using inter-subnet-forwarding,
each BT in the MAC-VRF would need a separate IRB. The same
procedures would apply.
2. Introduction and problem statement 2. Introduction and problem statement
Inter-subnet connectivity is required for certain tenants within the Inter-subnet connectivity is used for certain tenants within the Data
Data Center. [EVPN-INTERSUBNET] defines some fairly common inter- Center. [EVPN-INTERSUBNET] defines some fairly common inter-subnet
subnet forwarding scenarios where TSes can exchange packets with TSes forwarding scenarios where TSes can exchange packets with TSes
located in remote subnets. In order to meet this requirement, located in remote subnets. In order to achieve this,
[EVPN-INTERSUBNET] describes how MAC/IPs encoded in TS RT-2 routes [EVPN-INTERSUBNET] describes how MAC/IPs encoded in TS RT-2 routes
are not only used to populate MAC-VRF and overlay ARP tables, but are not only used to populate MAC-VRF and overlay ARP tables, but
also IP-VRF tables with the encoded TS host routes (/32 or /128). In also IP-VRF tables with the encoded TS host routes (/32 or /128). In
some cases, EVPN may advertise IP Prefixes and therefore provide some cases, EVPN may advertise IP Prefixes and therefore provide
aggregation in the IP-VRF tables, as opposed to program individual aggregation in the IP-VRF tables, as opposed to program individual
host routes. This document complements the scenarios described in host routes. This document complements the scenarios described in
[EVPN-INTERSUBNET] and defines how EVPN may be used to advertise IP [EVPN-INTERSUBNET] and defines how EVPN may be used to advertise IP
Prefixes. Prefixes. Interoperability between EVPN and L3VPN [RFC4364] IP Prefix
routes is out of the scope of this document.
Section 2.1 describes the inter-subnet connectivity requirements in Section 2.1 describes the inter-subnet connectivity requirements in
Data Centers. Section 2.2 explains why a new EVPN route type is Data Centers. Section 2.2 explains why a new EVPN route type is
required for IP Prefix advertisements. Once the need for a new EVPN required for IP Prefix advertisements. Once the need for a new EVPN
route type is justified, sections 3, 4 and 5 will describe this route route type is justified, sections 3, 4 and 5 will describe this route
type and how it is used in some specific use cases. type and how it is used in some specific use cases.
2.1 Inter-subnet connectivity requirements in Data Centers 2.1 Inter-subnet connectivity requirements in Data Centers
[RFC7432] is used as the control plane for a Network Virtualization [RFC7432] is used as the control plane for a Network Virtualization
Overlay (NVO3) solution in Data Centers (DC), where Network Overlay (NVO3) solution in Data Centers (DC), where Network
Virtualization Edge (NVE) devices can be located in Hypervisors or Virtualization Edge (NVE) devices can be located in Hypervisors or
TORs, as described in [EVPN-OVERLAY]. TORs, as described in [EVPN-OVERLAY].
If we use the term Tenant System (TS) to designate a physical or If we use the term Tenant System (TS) to designate a physical or
virtual system identified by MAC and IP addresses, and connected to virtual system identified by MAC and IP addresses, and connected to a
an EVPN instance, the following considerations apply: MAC-VRF by an Attachment Circuit, the following considerations apply:
o The Tenant Systems may be Virtual Machines (VMs) that generate o The Tenant Systems may be Virtual Machines (VMs) that generate
traffic from their own MAC and IP. traffic from their own MAC and IP.
o The Tenant Systems may be Virtual Appliance entities (VAs) that o The Tenant Systems may be Virtual Appliance entities (VAs) that
forward traffic to/from IP addresses of different End Devices forward traffic to/from IP addresses of different End Devices
seating behind them. sitting behind them.
o These VAs can be firewalls, load balancers, NAT devices, other o These VAs can be firewalls, load balancers, NAT devices, other
appliances or virtual gateways with virtual routing instances. appliances or virtual gateways with virtual routing instances.
o These VAs do not have their own routing protocols and hence o These VAs do not necessarily participate in dynamic routing
rely on the EVPN NVEs to advertise the routes on their behalf. protocols and hence rely on the EVPN NVEs to advertise the
routes on their behalf.
o In all these cases, the VA will forward traffic to the Data o In all these cases, the VA will forward traffic to other TSes
Center using its own source MAC but the source IP will be the using its own source MAC but the source IP will be the one
one associated to the End Device seating behind or a associated to the End Device sitting behind or a translated IP
translated IP address (part of a public NAT pool) if the VA is address (part of a public NAT pool) if the VA is performing
performing NAT. NAT.
o Note that the same IP address could exist behind two of these o Note that the same IP address could exist behind two of these
TS. One example of this would be certain appliance resiliency TS. One example of this would be certain appliance resiliency
mechanisms, where a virtual IP or floating IP can be owned by mechanisms, where a virtual IP or floating IP can be owned by
one of the two VAs running the resiliency protocol (the master one of the two VAs running the resiliency protocol (the master
VA). VRRP is one particular example of this. Another example VA). Virtual Router Redundancy Protocol (VRRP), RFC5798, is
is multi-homed subnets, i.e. the same subnet is connected to one particular example of this. Another example is multi-homed
two VAs. subnets, i.e. the same subnet is connected to two VAs.
o Although these VAs provide IP connectivity to VMs and subnets o Although these VAs provide IP connectivity to VMs and subnets
behind them, they do not always have their own IP interface behind them, they do not always have their own IP interface
connected to the EVPN NVE, e.g. layer-2 firewalls are examples connected to the EVPN NVE, e.g. layer-2 firewalls are examples
of VAs not supporting IP interfaces. of VAs not supporting IP interfaces.
The following figure illustrates some of the examples described Figure 1 illustrates some of the examples described above.
above.
NVE1 NVE1
+-----------+ +-----------+
TS1(VM)--|(MAC-VRF10)|-----+ TS1(VM)--|(MAC-VRF10)|-----+
IP1/M1 +-----------+ | DGW1 IP1/M1 +-----------+ | DGW1
+---------+ +-------------+ +---------+ +-------------+
| |----|(MAC-VRF10) | | |----|(MAC-VRF10) |
SN1---+ NVE2 | | | IRB1\ | SN1---+ NVE2 | | | IRB1\ |
| +-----------+ | | | (IP-VRF)|---+ | +-----------+ | | | (IP-VRF)|---+
SN2---TS2(VA)--|(MAC-VRF10)|-| | +-------------+ _|_ SN2---TS2(VA)--|(MAC-VRF10)|-| | +-------------+ _|_
| IP2/M2 +-----------+ | VXLAN/ | ( ) | IP2/M2 +-----------+ | VXLAN/ | ( )
skipping to change at page 6, line 8 skipping to change at page 6, line 44
Figure 1 DC inter-subnet use-cases Figure 1 DC inter-subnet use-cases
Where: Where:
NVE1, NVE2, NVE3, NVE4, NVE5, DGW1 and DGW2 share the same EVI for a NVE1, NVE2, NVE3, NVE4, NVE5, DGW1 and DGW2 share the same EVI for a
particular tenant. EVI-10 is comprised of the collection of MAC-VRF10 particular tenant. EVI-10 is comprised of the collection of MAC-VRF10
instances defined in all the NVEs. All the hosts connected to EVI-10 instances defined in all the NVEs. All the hosts connected to EVI-10
belong to the same IP subnet. The hosts connected to EVI-10 are belong to the same IP subnet. The hosts connected to EVI-10 are
listed below: listed below:
o TS1 is a VM that generates/receives traffic from/to IP1, where o TS1 is a VM that generates/receives traffic from/to IP1, where IP1
IP1 belongs to the EVI-10 subnet. belongs to the EVI-10 subnet.
o TS2 and TS3 are Virtual Appliances (VA) that generate/receive o TS2 and TS3 are Virtual Appliances (VA) that generate/receive
traffic from/to the subnets and hosts seating behind them traffic from/to the subnets and hosts sitting behind them (SN1,
(SN1, SN2, SN3, IP4 and IP5). Their IP addresses (IP2 and IP3) SN2, SN3, IP4 and IP5). Their IP addresses (IP2 and IP3) belong to
belong to the EVI-10 subnet and they can also generate/receive the EVI-10 subnet and they can also generate/receive traffic. When
traffic. When these VAs receive packets destined to their own these VAs receive packets destined to their own MAC addresses (M2
MAC addresses (M2 and M3) they will route the packets to the and M3) they will route the packets to the proper subnet or host.
proper subnet or host. These VAs do not support routing
protocols to advertise the subnets connected to them and can
move to a different server and NVE when the Cloud Management
System decides to do so. These VAs may also support redundancy
mechanisms for some subnets, similar to VRRP, where a floating
IP is owned by the master VA and only the master VA forwards
traffic to a given subnet. E.g.: vIP23 in figure 1 is a
floating IP that can be owned by TS2 or TS3 depending on who
the master is. Only the master will forward traffic to SN1.
o Integrated Routing and Bridging interfaces IRB1, IRB2 and IRB3 These VAs do not support routing protocols to advertise the subnets
have their own IP addresses that belong to the EVI-10 subnet connected to them and can move to a different server and NVE when
too. These IRB interfaces connect the EVI-10 subnet to Virtual the Cloud Management System decides to do so. These VAs may also
Routing and Forwarding (IP-VRF) instances that can route the support redundancy mechanisms for some subnets, similar to VRRP,
traffic to other connected subnets for the same tenant (within where a floating IP is owned by the master VA and only the master
the DC or at the other end of the WAN). VA forwards traffic to a given subnet. E.g.: vIP23 in figure 1 is a
floating IP that can be owned by TS2 or TS3 depending on who the
master is. Only the master will forward traffic to SN1.
o TS4 is a layer-2 VA that provides connectivity to subnets SN5, o Integrated Routing and Bridging interfaces IRB1, IRB2 and IRB3 have
SN6 and SN7, but does not have an IP address itself in the their own IP addresses that belong to the EVI-10 subnet too. These
EVI-10. TS4 is connected to a physical port on NVE5 assigned IRB interfaces connect the EVI-10 subnet to Virtual Routing and
to Ethernet Segment Identifier 4. Forwarding (IP-VRF) instances that can route the traffic to other
connected subnets for the same tenant (within the DC or at the
other end of the WAN).
o TS4 is a layer-2 VA that provides connectivity to subnets SN5, SN6
and SN7, but does not have an IP address itself in the EVI-10. TS4
is connected to a physical port on NVE5 assigned to Ethernet
Segment Identifier 4.
All the above DC use cases require inter-subnet forwarding and All the above DC use cases require inter-subnet forwarding and
therefore the individual host routes and subnets: therefore the individual host routes and subnets:
a) MUST be advertised from the NVEs (since VAs and VMs do not run a) MUST be advertised from the NVEs (since VAs and VMs do not
routing protocols) and participate in dynamic routing protocols) and
b) MAY be associated to an overlay index that can be a VA IP address, b) MAY be associated to an Overlay Index that can be a VA IP address,
a floating IP address or an ESI. a floating IP address, a MAC address or an ESI. An Overlay Index
is a next-hop that requires a recursive resolution and it is
described in section 3.2.
2.2 The requirement for a new EVPN route type 2.2 The requirement for a new EVPN route type
[RFC7432] defines a MAC/IP route (also referred as RT-2) where a MAC [RFC7432] defines a MAC/IP route (also referred as RT-2) where a MAC
address can be advertised together with an IP address length (IPL) address can be advertised together with an IP address length (IPL)
and IP address (IP). While a variable IPL might have been used to and IP address (IP). While a variable IPL might have been used to
indicate the presence of an IP prefix in a route type 2, there are indicate the presence of an IP prefix in a route type 2, there are
several specific use cases in which using this route type to deliver several specific use cases in which using this route type to deliver
IP Prefixes is not suitable. IP Prefixes is not suitable.
One example of such use cases is the "floating IP" example described One example of such use cases is the "floating IP" example described
in section 2.1. In this example we need to decouple the advertisement in section 2.1. In this example we need to decouple the advertisement
of the prefixes from the advertisement of the floating IP (vIP23 in of the prefixes from the advertisement of the floating IP (vIP23 in
figure 1) and MAC associated to it, otherwise the solution gets Figure 1) and MAC associated to it, otherwise the solution gets
highly inefficient and does not scale. highly inefficient and does not scale.
E.g.: if we are advertising 1k prefixes from M2 (using RT-2) and the E.g.: if we are advertising 1k prefixes from M2 (using RT-2) and the
floating IP owner changes from M2 to M3, we would need to withdraw 1k floating IP owner changes from M2 to M3, we would need to withdraw 1k
routes from M2 and re-advertise 1k routes from M3. However if we use routes from M2 and re-advertise 1k routes from M3. However if we use
a separate route type, we can advertise the 1k routes associated to a separate route type, we can advertise the 1k routes associated to
the floating IP address (vIP23) and only one RT-2 for advertising the the floating IP address (vIP23) and only one RT-2 for advertising the
ownership of the floating IP, i.e. vIP23 and M2 in the route type 2. ownership of the floating IP, i.e. vIP23 and M2 in the route type 2.
When the floating IP owner changes from M2 to M3, a single RT-2 When the floating IP owner changes from M2 to M3, a single RT-2
withdraw/update is required to indicate the change. The remote DGW withdraw/update is required to indicate the change. The remote DGW
will not change any of the 1k prefixes associated to vIP23, but will will not change any of the 1k prefixes associated to vIP23, but will
only update the ARP resolution entry for vIP23 (now pointing at M3). only update the ARP resolution entry for vIP23 (now pointing at M3).
Other reasons to decouple the IP Prefix advertisement from the MAC/IP Other reasons to decouple the IP Prefix advertisement from the MAC/IP
route are listed below: route are listed below:
o Clean identification, operation of troubleshooting of IP o Clean identification, operation and troubleshooting of IP Prefixes,
Prefixes, not subject to interpretation and independent of the independent of and not subject to the interpretation of the IPL and
IPL and the IP value. E.g.: a default IP route 0.0.0.0/0 must the IP value. E.g.: a default IP route 0.0.0.0/0 must always be
always be easily and clearly distinguished from the absence of easily and clearly distinguished from the absence of IP
IP information. information.
o MAC address information must not be compared by BGP when
selecting two IP Prefix routes. If IP Prefixes were to be
advertised using MAC/IP routes, the MAC information would
always be present and part of the route key.
o IP Prefix routes must not be subject to MAC/IP route
procedures such as MAC mobility or aliasing. Prefixes
advertised from two different ESIs do not mean mobility; MACs
advertised from two different ESIs do mean mobility. Similarly
load balancing for IP prefixes is achieved through IP
mechanisms such as ECMP, and not through MAC route mechanisms
such as aliasing.
o NVEs that do not require processing IP Prefixes must have an o In MAC/IP routes, the MAC information is part of the NLRI, so if IP
easy way to identify an update with an IP Prefix and ignore Prefixes were to be advertised using MAC/IP routes, the MAC
it, rather than processing the MAC/IP route to find out only information would always be present and part of the route key.
later that it carries a Prefix that must be ignored.
The following sections describe how EVPN is extended with a new route The following sections describe how EVPN is extended with a new route
type for the advertisement of IP prefixes and how this route is used type for the advertisement of IP prefixes and how this route is used
to address the current and future inter-subnet connectivity to address the current and future inter-subnet connectivity
requirements existing in the Data Center. requirements existing in the Data Center.
3. The BGP EVPN IP Prefix route 3. The BGP EVPN IP Prefix route
The current BGP EVPN NLRI as defined in [RFC7432] is shown below: The current BGP EVPN NLRI as defined in [RFC7432] is shown below:
+-----------------------------------+ +-----------------------------------+
| Route Type (1 octet) | | Route Type (1 octet) |
+-----------------------------------+ +-----------------------------------+
| Length (1 octet) | | Length (1 octet) |
+-----------------------------------+ +-----------------------------------+
| Route Type specific (variable) | | Route Type specific (variable) |
+-----------------------------------+ +-----------------------------------+
Where the route type field can contain one of the following specific Where the route type field can contain one of the following specific
values: values (refer to the IANA "EVPN Route Types registry):
+ 1 - Ethernet Auto-Discovery (A-D) route + 1 - Ethernet Auto-Discovery (A-D) route
+ 2 - MAC/IP advertisement route + 2 - MAC/IP advertisement route
+ 3 - Inclusive Multicast Route + 3 - Inclusive Multicast Route
+ 4 - Ethernet Segment Route + 4 - Ethernet Segment Route
This document defines an additional route type that will be used for This document defines an additional route type that IANA has added to
the advertisement of IP Prefixes: the registry, and will be used for the advertisement of IP Prefixes:
+ 5 - IP Prefix Route + 5 - IP Prefix Route
The support for this new route type is OPTIONAL. The support for this new route type is OPTIONAL.
Since this new route type is OPTIONAL, an implementation not Since this new route type is OPTIONAL, an implementation not
supporting it MUST ignore the route, based on the unknown route type supporting it MUST ignore the route, based on the unknown route type
value. value, as specified by Section 5.4 in [RFC7606].
The detailed encoding of this route and associated procedures are The detailed encoding of this route and associated procedures are
described in the following sections. described in the following sections.
3.1 IP Prefix Route encoding 3.1 IP Prefix Route encoding
An IP Prefix advertisement route NLRI consists of the following An IP Prefix advertisement route NLRI consists of the following
fields: fields:
+---------------------------------------+ +---------------------------------------+
skipping to change at page 9, line 23 skipping to change at page 9, line 45
+---------------------------------------+ +---------------------------------------+
| IP Prefix (4 or 16 octets) | | IP Prefix (4 or 16 octets) |
+---------------------------------------+ +---------------------------------------+
| GW IP Address (4 or 16 octets) | | GW IP Address (4 or 16 octets) |
+---------------------------------------+ +---------------------------------------+
| MPLS Label (3 octets) | | MPLS Label (3 octets) |
+---------------------------------------+ +---------------------------------------+
Where: Where:
o RD, Ethernet Tag ID and MPLS Label fields will be used as o RD, Ethernet Tag ID and MPLS Label fields will be used as defined
defined in [RFC7432] and [EVPN-OVERLAY]. in [RFC7432] and [EVPN-OVERLAY].
o The Ethernet Segment Identifier will be a non-zero 10-byte o The Ethernet Segment Identifier will be a non-zero 10-byte
identifier if the ESI is used as an overlay index. It will be identifier if the ESI is used as an Overlay Index (see the
zero otherwise. definition of Overlay Index in section 3.2). It will be zero
otherwise.
o The IP Prefix Length can be set to a value between 0 and 32 o The IP Prefix Length can be set to a value between 0 and 32 (bits)
(bits) for ipv4 and between 0 and 128 for ipv6. for ipv4 and between 0 and 128 for ipv6, and specifies the number
of bits in the Prefix.
o The IP Prefix will be a 32 or 128-bit field (ipv4 or ipv6). o The IP Prefix will be a 32 or 128-bit field (ipv4 or ipv6). The
size of this field does not depend on the value of the IP Prefix
Length field.
o The GW IP (Gateway IP Address) will be a 32 or 128-bit field o The GW IP (Gateway IP Address) will be a 32 or 128-bit field (ipv4
(ipv4 or ipv6), and will encode an overlay IP index for the IP or ipv6), and will encode an overlay IP index for the IP Prefixes.
Prefixes. The GW IP field SHOULD be zero if it is not used as The GW IP field SHOULD be zero if it is not used as an Overlay
an overlay index. Index. Refer to section 3.2 for the definition and use of the
Overlay Index.
o The MPLS Label field is encoded as 3 octets, where the high- o The MPLS Label field is encoded as 3 octets, where the high-order
order 20 bits contain the label value. The value SHOULD be 20 bits contain the label value. When sending, the label value
null when the IP Prefix route is used for a recursive lookup SHOULD be zero to indicate that recursive resolution is needed. If
resolution. the received MPLS Label value is zero, the route MUST contain an
Overlay Index and the ingress NVE/PE MUST do recursive resolution
to find the egress NVE/PE. If the received Label value is non-zero,
the route will not be used for recursive resolution unless a local
policy says so.
o The total route length will indicate the type of prefix (ipv4 o The total route length will indicate the type of prefix (ipv4 or
or ipv6) and the type of GW IP address (ipv4 or ipv6). Note ipv6) and the type of GW IP address (ipv4 or ipv6). Note that the
that the IP Prefix + the GW IP should have a length of either IP Prefix + the GW IP should have a length of either 64 or 256
64 or 256 bits, but never 160 bits (ipv4 and ipv6 mixed values bits, but never 160 bits (ipv4 and ipv6 mixed values are not
are not allowed). allowed).
The Eth-Tag ID, IP Prefix Length and IP Prefix will be part of the The RD, Eth-Tag ID, IP Prefix Length and IP Prefix will be part of
route key used by BGP to compare routes. The rest of the fields will the route key used by BGP to compare routes. The rest of the fields
not be part of the route key. will not be part of the route key.
The route will contain a single overlay index at most, i.e. if the 3.2 Overlay Indexes and Recursive Lookup Resolution
ESI field is different from zero, the GW IP field will be zero, and
vice versa. The following table shows the different inter-subnet use-
cases described in this document and the corresponding coding of the
overlay index in the route type 5 (RT-5). The IP-VRF-to-IP-VRF or IRB
forwarding on NVEs case is a special use-case, where there may be no
need for overlay index, since the actual next-hop is given by the BGP
next-hop. When an overlay index is present in the RT-5, the receiving
NVE will need to perform a recursive route resolution to find out to
which egress NVE to forward the packets.
+----------------------------+--------------------------------------+ RT-5 routes support recursive lookup resolution through the use of
| Use-case | Overlay Index in the RT-5 BGP update | Overlay Indexes as follows:
+----------------------------+--------------------------------------+
| TS IP address | Overlay GW IP Address |
| Floating IP address | Overlay GW IP Address |
| "Bump in the wire" | ESI |
| IP-VRF-to-IP-VRF | Overlay GW IP, MAC or N/A |
+----------------------------+--------------------------------------+
4. Benefits of using the EVPN IP Prefix route o An Overlay Index can be an ESI, IP address in the address space of
the tenant or MAC address and it is used by an NVE as the next-hop
for a given IP Prefix. An Overlay Index always needs a recursive
route resolution on the NVE/PE that installs the RT-5 into one of
its IP-VRFs, so that the NVE knows to which egress NVE/PE it needs
to forward the packets. It is important to note that recursive
resolution of the Overlay Index applies upon installation into an
IP-VRF, and not upon BGP propagation. Also, as a result of the
recursive resolution, the egress NVE/PE is not necessarily the same
NVE that originated the RT-5.
This section clarifies the different functions accomplished by the o The Overlay Index is indicated along with the RT-5 in the ESI
EVPN RT-2 and RT-5 routes, and provides a list of benefits derived field, GW IP field or Router's MAC Extended Community, depending on
from using a separate route type for the advertisement of IP Prefixes whether the IP Prefix next-hop is an ESI, IP address or MAC address
in EVPN. in the tenant space. The Overlay Index for a given IP Prefix is set
by local policy at the NVE that originates an RT-5 for that IP
Prefix (typically managed by the Cloud Management System).
[RFC7432] describes the content of the BGP EVPN RT-2 specific NLRI, o In order to enable the recursive lookup resolution at the ingress
i.e. MAC/IP Advertisement Route, where the IP address length (IPL) NVE, an NVE that is a possible egress NVE for a given Overlay Index
and IP address (IP) of a specific advertised MAC are encoded. The must originate a route advertising itself as the BGP next hop on
subject of the MAC advertisement route is the MAC address (M) and MAC the path to the system denoted by the Overlay Index. For instance:
address length (ML) encoded in the route. The MAC mobility and other
procedures are defined around that MAC address. The IP address
information carries the host IP address required for the ARP
resolution of the MAC according to [RFC7432] and the host route to be
programmed in the IP-VRF [EVPN-INTERSUBNET].
The BGP EVPN route type 5 defined in this document, i.e. IP Prefix . If an NVE receives an RT-5 that specifies an Overlay Index, the
Advertisement route, decouples the advertisement of IP prefixes from NVE cannot use the RT-5 in its IP-VRF unless (or until) it can
the advertisement of any MAC address related to it. This brings some recursively resolve the Overlay Index.
major benefits to NVO-based networks where certain inter-subnet . If the RT-5 specifies an ESI as the Overlay Index, recursive
forwarding scenarios are required. Some of those benefits are: resolution can only be done if the NVE has received and installed
an RT-1 (Auto-Discovery per-EVI) route specifying that ESI.
. If the RT-5 specifies a GW IP address as the Overlay Index,
recursive resolution can only be done if the NVE has received and
installed an RT-2 (MAC/IP route) specifying that IP address in
the IP address field of its NLRI.
. If the RT-5 specifies a MAC address as the Overlay Index,
recursive resolution can only be done if the NVE has received and
installed an RT-2 (MAC/IP route) specifying that MAC address in
the MAC address field of its NLRI.
a) Upon receiving a route type 2 or type 5, an egress NVE can easily Note that the RT-1 or RT-2 routes needed for the recursive
distinguish MACs and IPs from IP Prefixes. E.g. an IP prefix with resolution may arrive before or after the given RT-5 route.
IPL=32 being advertised from two different ingress NVEs (as RT-5)
can be identified as such and be imported in the designated
routing context as two ECMP routes, as opposed to two MACs
competing for the same IP.
b) Similarly, upon receiving a route, an ingress NVE not supporting o Irrespective of the recursive resolution, if there is no IGP or BGP
processing of IP Prefixes can easily ignore the update, based on route to the BGP next-hop of an RT-5, BGP may fail to install the
the route type. RT-5 even if the Overlay Index can be resolved.
c) A MAC route includes the ML, M, IPL and IP in the route key that o The ESI and GW IP fields MAY both be zero, however they MUST NOT
is used by BGP to compare routes, whereas for IP Prefix routes, both be non-zero at the same time. A route containing a non-zero GW
only IPL and IP (as well as Ethernet Tag ID) are part of the route IP and a non-zero ESI (at the same time) will be treated as-
key. Advertised IP Prefixes are imported into the designated withdraw.
routing context, where there is no MAC information associated to
IP routes. In the example illustrated in figure 1, subnet SN1
should be advertised by NVE2 and NVE3 and interpreted by DGW1 as
the same route coming from two different next-hops, regardless of
the MAC address associated to TS2 or TS3. This is easily
accomplished in the RT-5 by including only the IP information in
the route key.
d) By decoupling the MAC from the IP Prefix advertisement procedures, The indirection provided by the Overlay Index and its recursive
we can leave the IP Prefix advertisements out of the MAC mobility lookup resolution is required to achieve fast convergence in case of
procedures defined in [RFC7432] for MACs. In addition, this allows a failure of the object represented by the Overlay Index. For
us to have an indirection mechanism for IP Prefixes advertised instance: in Figure 1, let's assume NVE2/NVE3 advertise 1k RT-5
from a MAC/IP that can move between hypervisors. E.g. if there are routes associated to the floating IP address (GWIP=vIP23) and NVE2
1,000 prefixes seating behind TS2 (figure 1), NVE2 will advertise advertises an RT-2 claiming the ownership of the floating IP, i.e.
all those prefixes in RT-5 routes associated to the overlay index NVE2 encodes vIP23 and M2 in the RT-2. When the floating IP owner
IP2. Should TS2 move to a different NVE, a single MAC/IP changes from M2 to M3, a single RT-2 withdraw/update is required to
advertisement route withdraw for the M2/IP2 route from NVE2 will indicate the change. The remote DGW will not change any of the 1k
invalidate the 1,000 prefixes, as opposed to have to wait for each prefixes associated to vIP23, but will only update the ARP resolution
individual prefix to be withdrawn. This may be easily accomplished entry for vIP23 (now pointing at M3).
by using IP Prefix routes that are not tied to a MAC address, and
use a different MAC/IP route to advertise the location and
resolution of the overlay index to a MAC address.
5. IP Prefix overlay index use-cases Table 1 shows the different RT-5 field combinations allowed by this
specification and what Overlay Index must be used by the receiving
NVE/PE in each case. When the Overlay Index is "None" in Table 1, the
receiving NVE/PE will not perform any recursive resolution, and the
actual next-hop is given by the RT-5's BGP next-hop.
The IP Prefix route can use a GW IP or an ESI as an overlay index as +----------+----------+----------+------------+----------------+
well as no overlay index whatsoever. This section describes some use- | ESI | GW-IP | MAC* | Label | Overlay Index |
cases for these index types. |--------------------------------------------------------------|
| Non-Zero | Zero | Zero | Don't Care | ESI |
| Non-Zero | Zero | Non-Zero | Don't Care | ESI |
| Zero | Non-Zero | Zero | Don't Care | GW-IP |
| Zero | Zero | Non-Zero | Zero | MAC |
| Zero | Zero | Non-Zero | Non-Zero | MAC or None** |
| Zero | Zero | Zero | Non-Zero | None(IP NVO)***|
+----------+----------+----------+------------+----------------+
5.1 TS IP address overlay index use-case Table 1 - RT-5 fields and Indicated Overlay Index
Table NOTES:
* MAC with Zero value means no Router's MAC extended community is
present along with the RT-5. Non-Zero indicates that the extended
community is present and carries a valid MAC address. Examples of
invalid MAC addresses are broadcast or multicast MAC addresses.
** In this case, the Overlay Index may be the RT-5's MAC address or
None, depending on the local policy of the receiving NVE/PE.
*** The Overlay Index is None. This is a special case used for IP-
VRF-to-IP-VRF where the NVE/PEs are connected by IP NVO tunnels
as opposed to Ethernet NVO tunnels.
Table 2 shows the different inter-subnet use-cases described in this
document and the corresponding coding of the Overlay Index in the
route type 5 (RT-5).
+---------+---------------------+----------------------------+
| Section | Use-case | Overlay Index in the RT-5 |
+-------------------------------+----------------------------+
| 4.1 | TS IP address | GW IP |
| 4.2 | Floating IP address | GW IP |
| 4.3 | "Bump in the wire" | ESI or MAC |
| 4.4 | IP-VRF-to-IP-VRF | GW IP, MAC or None |
+---------+---------------------+----------------------------+
Table 2 - Use-cases and Overlay Indexes for Recursive Resolution
The above use-cases are representative of the different Overlay
Indexes supported by RT-5 (GW IP, ESI, MAC or None). Any other use-
case using a given Overlay Index, SHOULD follow the procedures
described in this document for the same Overlay Index.
4. IP Prefix Overlay Index use-cases
This section describes some use-cases for the Overlay Index types.
4.1 TS IP address Overlay Index use-case
The following figure illustrates an example of inter-subnet The following figure illustrates an example of inter-subnet
forwarding for subnets seating behind Virtual Appliances (on TS2 and forwarding for subnets sitting behind Virtual Appliances (on TS2 and
TS3). TS3).
SN1---+ NVE2 DGW1 SN1---+ NVE2 DGW1
| +-----------+ +---------+ +-------------+ | +-----------+ +---------+ +-------------+
SN2---TS2(VA)--|(MAC-VRF10)|-| |----|(MAC-VRF10) | SN2---TS2(VA)--|(MAC-VRF10)|-| |----|(MAC-VRF10) |
| IP2/M2 +-----------+ | | | IRB1\ | | IP2/M2 +-----------+ | | | IRB1\ |
IP4---+ | | | (IP-VRF)|---+ IP4---+ | | | (IP-VRF)|---+
| | +-------------+ _|_ | | +-------------+ _|_
| VXLAN/ | ( ) | VXLAN/ | ( )
| nvGRE | DGW2 ( WAN ) | nvGRE | DGW2 ( WAN )
SN1---+ NVE3 | | +-------------+ (___) SN1---+ NVE3 | | +-------------+ (___)
| IP3/M3 +-----------+ | |----|(MAC-VRF10) | | | IP3/M3 +-----------+ | |----|(MAC-VRF10) | |
SN3---TS3(VA)--|(MAC-VRF10)|-| | | IRB2\ | | SN3---TS3(VA)--|(MAC-VRF10)|-| | | IRB2\ | |
| +-----------+ +---------+ | (IP-VRF)|---+ | +-----------+ +---------+ | (IP-VRF)|---+
IP5---+ +-------------+ IP5---+ +-------------+
Figure 2 TS IP address use-case Figure 2 TS IP address use-case
An example of inter-subnet forwarding between subnet SN1/24 and a An example of inter-subnet forwarding between subnet SN1/24 and a
subnet seating in the WAN is described below. NVE2, NVE3, DGW1 and subnet sitting in the WAN is described below. NVE2, NVE3, DGW1 and
DGW2 are running BGP EVPN. TS2 and TS3 do not support routing DGW2 are running BGP EVPN. TS2 and TS3 do not participate in dynamic
protocols, only a static route to forward the traffic to the WAN. routing protocols, and they only have a static route to forward the
traffic to the WAN.
In this case, a GW IP is used as an Overlay Index. Although a
different Overlay Index type could have been used, this use-case
assumes that the operator knows the VA's IP addresses beforehand,
whereas the VA's MAC address is unknown and the VA's ESI is zero.
Because of this, the GW IP is the suitable Overlay Index to be used
with the RT-5s. The NVEs know the GW IP to be used for a given Prefix
by policy.
(1) NVE2 advertises the following BGP routes on behalf of TS2: (1) NVE2 advertises the following BGP routes on behalf of TS2:
o Route type 2 (MAC/IP route) containing: ML=48, M=M2, IPL=32, o Route type 2 (MAC/IP route) containing: ML=48, M=M2, IPL=32,
IP=IP2 and [RFC5512] BGP Encapsulation Extended Community with IP=IP2 and [RFC5512] BGP Encapsulation Extended Community with
the corresponding Tunnel-type. the corresponding Tunnel-type. The MAC and IP addresses may be
learned via ARP-snooping (ND-snooping if IPv6).
o Route type 5 (IP Prefix route) containing: IPL=24, IP=SN1, o Route type 5 (IP Prefix route) containing: IPL=24, IP=SN1,
ESI=0, GW IP address=IP2. ESI=0, GW IP address=IP2. The prefix and GW IP are learned by
policy.
(2) NVE3 advertises the following BGP routes on behalf of TS3: (2) Similarly, NVE3 advertises the following BGP routes on behalf of
TS3:
o Route type 2 (MAC/IP route) containing: ML=48, M=M3, IPL=32, o Route type 2 (MAC/IP route) containing: ML=48, M=M3, IPL=32,
IP=IP3 (and BGP Encapsulation Extended Community). IP=IP3 (and BGP Encapsulation Extended Community).
o Route type 5 (IP Prefix route) containing: IPL=24, IP=SN1, o Route type 5 (IP Prefix route) containing: IPL=24, IP=SN1,
ESI=0, GW IP address=IP3. ESI=0, GW IP address=IP3.
(3) DGW1 and DGW2 import both received routes based on the (3) DGW1 and DGW2 import both received routes based on the
route-targets: route-targets:
o Based on the MAC-VRF10 route-target in DGW1 and DGW2, the o Based on the MAC-VRF10 route-target in DGW1 and DGW2, the
MAC/IP route is imported and M2 is added to the MAC-VRF10 MAC/IP route is imported and M2 is added to the MAC-VRF10
along with its corresponding tunnel information. For instance, along with its corresponding tunnel information. For instance,
if VXLAN is used, the VTEP will be derived from the MAC/IP if VXLAN is used, the VTEP will be derived from the MAC/IP
route BGP next-hop (underlay next-hop) and VNI from the MPLS route BGP next-hop and VNI from the MPLS Label1 field. IP2 -
Label1 field. IP2 - M2 is added to the ARP table. M2 is added to the ARP table. Similarly, M3 is added to MAC-
VRF10 and IP3 - M3 to the ARP table.
o Based on the MAC-VRF10 route-target in DGW1 and DGW2, the IP o Based on the MAC-VRF10 route-target in DGW1 and DGW2, the IP
Prefix route is also imported and SN1/24 is added to the IP- Prefix route is also imported and SN1/24 is added to the IP-
VRF with overlay index IP2 pointing at the local MAC-VRF10. VRF with Overlay Index IP2 pointing at the local MAC-VRF10. We
Should ECMP be enabled in the IP-VRF, SN1/24 would also be assume the RT-5 from NVE2 is preferred over the RT-5 from
added to the routing table with overlay index IP3. NVE3. Should ECMP be enabled in the IP-VRF and both routes
equally preferable, SN1/24 would also be added to the routing
table with Overlay Index IP3.
(4) When DGW1 receives a packet from the WAN with destination IPx, (4) When DGW1 receives a packet from the WAN with destination IPx,
where IPx belongs to SN1/24: where IPx belongs to SN1/24:
o A destination IP lookup is performed on the DGW1 IP-VRF o A destination IP lookup is performed on the DGW1 IP-VRF
routing table and overlay index=IP2 is found. Since IP2 is an routing table and Overlay Index=IP2 is found. Since IP2 is an
overlay index a recursive route resolution is required for Overlay Index a recursive route resolution is required for
IP2. IP2.
o IP2 is resolved to M2 in the ARP table, and M2 is resolved to o IP2 is resolved to M2 in the ARP table, and M2 is resolved to
the tunnel information given by the MAC-VRF FIB (e.g. remote the tunnel information given by the MAC-VRF FIB (e.g. remote
VTEP and VNI for the VXLAN case). VTEP and VNI for the VXLAN case).
o The IP packet destined to IPx is encapsulated with: o The IP packet destined to IPx is encapsulated with:
. Source inner MAC = IRB1 MAC. . Source inner MAC = IRB1 MAC.
skipping to change at page 13, line 46 skipping to change at page 15, line 40
o Encapsulation is stripped-off and based on a MAC lookup o Encapsulation is stripped-off and based on a MAC lookup
(assuming MAC forwarding on the egress NVE), the packet is (assuming MAC forwarding on the egress NVE), the packet is
forwarded to TS2, where it will be properly routed. forwarded to TS2, where it will be properly routed.
(6) Should TS2 move from NVE2 to NVE3, MAC Mobility procedures will (6) Should TS2 move from NVE2 to NVE3, MAC Mobility procedures will
be applied to the MAC route IP2/M2, as defined in [RFC7432]. be applied to the MAC route IP2/M2, as defined in [RFC7432].
Route type 5 prefixes are not subject to MAC mobility procedures, Route type 5 prefixes are not subject to MAC mobility procedures,
hence no changes in the DGW IP-VRF routing table will occur for hence no changes in the DGW IP-VRF routing table will occur for
TS2 mobility, i.e. all the prefixes will still be pointing at IP2 TS2 mobility, i.e. all the prefixes will still be pointing at IP2
as overlay index. There is an indirection for e.g. SN1/24, which as Overlay Index. There is an indirection for e.g. SN1/24, which
still points at overlay index IP2 in the routing table, but IP2 still points at Overlay Index IP2 in the routing table, but IP2
will be simply resolved to a different tunnel, based on the will be simply resolved to a different tunnel, based on the
outcome of the MAC mobility procedures for the MAC/IP route outcome of the MAC mobility procedures for the MAC/IP route
IP2/M2. IP2/M2.
Note that in the opposite direction, TS2 will send traffic based on Note that in the opposite direction, TS2 will send traffic based on
its static-route next-hop information (IRB1 and/or IRB2), and regular its static-route next-hop information (IRB1 and/or IRB2), and regular
EVPN procedures will be applied. EVPN procedures will be applied.
5.2 Floating IP overlay index use-case 4.2 Floating IP Overlay Index use-case
Sometimes Tenant Systems (TS) work in active/standby mode where an Sometimes Tenant Systems (TS) work in active/standby mode where an
upstream floating IP - owned by the active TS - is used as the upstream floating IP - owned by the active TS - is used as the
overlay index to get to some subnets behind. This redundancy mode, Overlay Index to get to some subnets behind. This redundancy mode,
already introduced in section 2.1 and 2.2, is illustrated in Figure already introduced in section 2.1 and 2.2, is illustrated in Figure
3. 3.
NVE2 DGW1 NVE2 DGW1
+-----------+ +---------+ +-------------+ +-----------+ +---------+ +-------------+
+---TS2(VA)--|(MAC-VRF10)|-| |----|(MAC-VRF10) | +---TS2(VA)--|(MAC-VRF10)|-| |----|(MAC-VRF10) |
| IP2/M2 +-----------+ | | | IRB1\ | | IP2/M2 +-----------+ | | | IRB1\ |
| <-+ | | | (IP-VRF)|---+ | <-+ | | | (IP-VRF)|---+
| | | | +-------------+ _|_ | | | | +-------------+ _|_
SN1 vIP23 (floating) | VXLAN/ | ( ) SN1 vIP23 (floating) | VXLAN/ | ( )
| | | nvGRE | DGW2 ( WAN ) | | | nvGRE | DGW2 ( WAN )
| <-+ NVE3 | | +-------------+ (___) | <-+ NVE3 | | +-------------+ (___)
| IP3/M3 +-----------+ | |----|(MAC-VRF10) | | | IP3/M3 +-----------+ | |----|(MAC-VRF10) | |
+---TS3(VA)--|(MAC-VRF10)|-| | | IRB2\ | | +---TS3(VA)--|(MAC-VRF10)|-| | | IRB2\ | |
+-----------+ +---------+ | (IP-VRF)|---+ +-----------+ +---------+ | (IP-VRF)|---+
+-------------+ +-------------+
Figure 3 Floating IP overlay index for redundant TS Figure 3 Floating IP Overlay Index for redundant TS
In this example, assuming TS2 is the active TS and owns IP23: In this use-case, a GW IP is used as an Overlay Index for the same
reasons as in 4.1. However, this GW IP is a floating IP that belongs
to the active TS. Assuming TS2 is the active TS and owns IP23:
(1) NVE2 advertises the following BGP routes for TS2: (1) NVE2 advertises the following BGP routes for TS2:
o Route type 2 (MAC/IP route) containing: ML=48, M=M2, IPL=32, o Route type 2 (MAC/IP route) containing: ML=48, M=M2, IPL=32,
IP=IP23 (and BGP Encapsulation Extended Community). IP=IP23 (and BGP Encapsulation Extended Community). The MAC
and IP addresses may be learned via ARP-snooping.
o Route type 5 (IP Prefix route) containing: IPL=24, IP=SN1, o Route type 5 (IP Prefix route) containing: IPL=24, IP=SN1,
ESI=0, GW IP address=IP23. ESI=0, GW IP address=IP23. The prefix and GW IP are learned by
policy.
(2) NVE3 advertises the following BGP routes for TS3: (2) NVE3 advertises the following BGP route for TS3 (it does not
advertise an RT-2 for IP23/M3):
o Route type 5 (IP Prefix route) containing: IPL=24, IP=SN1, o Route type 5 (IP Prefix route) containing: IPL=24, IP=SN1,
ESI=0, GW IP address=IP23. ESI=0, GW IP address=IP23. The prefix and GW IP are learned by
policy.
(3) DGW1 and DGW2 import both received routes based on the route- (3) DGW1 and DGW2 import both received routes based on the route-
target: target:
o M2 is added to the MAC-VRF10 FIB along with its corresponding o M2 is added to the MAC-VRF10 FIB along with its corresponding
tunnel information. For the VXLAN use case, the VTEP will be tunnel information. For the VXLAN use case, the VTEP will be
derived from the MAC/IP route BGP next-hop and VNI from the derived from the MAC/IP route BGP next-hop and VNI from the
VNI/VSID field. IP23 - M2 is added to the ARP table. VNI/VSID field. IP23 - M2 is added to the ARP table.
o SN1/24 is added to the IP-VRF in DGW1 and DGW2 with overlay o SN1/24 is added to the IP-VRF in DGW1 and DGW2 with Overlay
index IP23 pointing at the local MAC-VRF10. index IP23 pointing at M2 in the local MAC-VRF10.
(4) When DGW1 receives a packet from the WAN with destination IPx, (4) When DGW1 receives a packet from the WAN with destination IPx,
where IPx belongs to SN1/24: where IPx belongs to SN1/24:
o A destination IP lookup is performed on the DGW1 IP-VRF o A destination IP lookup is performed on the DGW1 IP-VRF
routing table and overlay index=IP23 is found. Since IP23 is routing table and Overlay Index=IP23 is found. Since IP23 is
an overlay index, a recursive route resolution for IP23 is an Overlay Index, a recursive route resolution for IP23 is
required. required.
o IP23 is resolved to M2 in the ARP table, and M2 is resolved to o IP23 is resolved to M2 in the ARP table, and M2 is resolved to
the tunnel information given by the MAC-VRF (remote VTEP and the tunnel information given by the MAC-VRF (remote VTEP and
VNI for the VXLAN case). VNI for the VXLAN case).
o The IP packet destined to IPx is encapsulated with: o The IP packet destined to IPx is encapsulated with:
. Source inner MAC = IRB1 MAC. . Source inner MAC = IRB1 MAC.
skipping to change at page 15, line 43 skipping to change at page 17, line 43
MAC-VRF10 context is identified for a MAC lookup. MAC-VRF10 context is identified for a MAC lookup.
o Encapsulation is stripped-off and based on a MAC lookup o Encapsulation is stripped-off and based on a MAC lookup
(assuming MAC forwarding on the egress NVE), the packet is (assuming MAC forwarding on the egress NVE), the packet is
forwarded to TS2, where it will be properly routed. forwarded to TS2, where it will be properly routed.
(6) When the redundancy protocol running between TS2 and TS3 appoints (6) When the redundancy protocol running between TS2 and TS3 appoints
TS3 as the new active TS for SN1, TS3 will now own the floating TS3 as the new active TS for SN1, TS3 will now own the floating
IP23 and will signal this new ownership (GARP message or IP23 and will signal this new ownership (GARP message or
similar). Upon receiving the new owner's notification, NVE3 will similar). Upon receiving the new owner's notification, NVE3 will
issue a route type 2 for M3-IP23. DGW1 and DGW2 will update their issue a route type 2 for M3-IP23 and NVE2 will withdraw the RT-2
ARP tables with the new MAC resolving the floating IP. No changes for M2-IP23. DGW1 and DGW2 will update their ARP tables with the
are carried out in the IP-VRF routing table. new MAC resolving the floating IP. No changes are made in the IP-
VRF routing table.
5.3 ESI overlay index ("Bump in the wire") use-case 4.3 Bump-in-the-wire use-case
Figure 5 illustrates an example of inter-subnet forwarding for an IP Figure 5 illustrates an example of inter-subnet forwarding for an IP
Prefix route that carries a subnet SN1 and uses an ESI as an overlay Prefix route that carries a subnet SN1. In this use-case, TS2 and TS3
index (ESI23). In this use-case, TS2 and TS3 are layer-2 VA devices are layer-2 VA devices without any IP address that can be included as
without any IP address that can be included as an overlay index in an Overlay Index in the GW IP field of the IP Prefix route. Their MAC
the GW IP field of the IP Prefix route. Their MAC addresses are M2 addresses are M2 and M3 respectively and are connected to EVI-10.
and M3 respectively and are connected to EVI-10. Note that IRB1 and Note that IRB1 and IRB2 (in DGW1 and DGW2 respectively) have IP
IRB2 (in DGW1 and DGW2 respectively) have IP addresses in a subnet addresses in a subnet different than SN1.
different than SN1.
NVE2 DGW1 NVE2 DGW1
M2 +-----------+ +---------+ +-------------+ M2 +-----------+ +---------+ +-------------+
+---TS2(VA)--|(MAC-VRF10)|-| |----|(MAC-VRF10) | +---TS2(VA)--|(MAC-VRF10)|-| |----|(MAC-VRF10) |
| ESI23 +-----------+ | | | IRB1\ | | ESI23 +-----------+ | | | IRB1\ |
| + | | | (IP-VRF)|---+ | + | | | (IP-VRF)|---+
| | | | +-------------+ _|_ | | | | +-------------+ _|_
SN1 | | VXLAN/ | ( ) SN1 | | VXLAN/ | ( )
| | | nvGRE | DGW2 ( WAN ) | | | nvGRE | DGW2 ( WAN )
| + NVE3 | | +-------------+ (___) | + NVE3 | | +-------------+ (___)
| ESI23 +-----------+ | |----|(MAC-VRF10) | | | ESI23 +-----------+ | |----|(MAC-VRF10) | |
+---TS3(VA)--|(MAC-VRF10)|-| | | IRB2\ | | +---TS3(VA)--|(MAC-VRF10)|-| | | IRB2\ | |
M3 +-----------+ +---------+ | (IP-VRF)|---+ M3 +-----------+ +---------+ | (IP-VRF)|---+
+-------------+ +-------------+
Figure 5 ESI overlay index use-case Figure 5 Bump-in-the-wire use-case
Since neither TS2 nor TS3 can run any routing protocol and have no IP Since neither TS2 nor TS3 can participate in any dynamic routing
address assigned, an ESI, i.e. ESI23, will be provisioned on the protocol and have no IP address assigned, there are two potential
attachment ports of NVE2 and NVE3. This model supports VA redundancy Overlay Index types that can be used when advertising SN1:
in a similar way as the one described in section 5.2 for the floating
IP overlay index use-case, only using the EVPN Ethernet A-D route
instead of the MAC advertisement route to advertise the location of
the overlay index. The procedure is explained below:
(1) NVE2 advertises the following BGP routes for TS2: a) an ESI, i.e. ESI23, that can be provisioned on the attachment
ports of NVE2 and NVE3, as shown in Figure 5.
b) or the VA's MAC address, that can be added to NVE2 and NVE3 by
policy.
The advantage of using an ESI as Overlay Index as opposed to the VA's
MAC address, is that the forwarding to the egress NVE can be done
purely based on the state of the AC in the ES (notified by the AD
per-EVI route) and all the EVPN multi-homing redundancy mechanisms
can be re-used. For instance, the [RFC7432] mass-withdrawal mechanism
for fast failure detection and propagation can be used. This section
assumes that an ESI Overlay Index is used in this use-case but it
does not prevent the use of the VA's MAC address as an Overlay Index.
If a MAC is used as Overlay Index, the control plane must follow the
procedures described in section 4.4.3.
The model supports VA redundancy in a similar way as the one
described in section 4.2 for the floating IP Overlay Index use-case,
except that it uses the EVPN Ethernet A-D per-EVI route instead of
the MAC advertisement route to advertise the location of the Overlay
Index. The procedure is explained below:
(1) Assuming TS2 is the active TS in ESI23, NVE2 advertises the
following BGP routes:
o Route type 1 (Ethernet A-D route for EVI-10) containing: o Route type 1 (Ethernet A-D route for EVI-10) containing:
ESI=ESI23 and the corresponding tunnel information (VNI/VSID ESI=ESI23 and the corresponding tunnel information (VNI/VSID
field), as well as the BGP Encapsulation Extended Community as field), as well as the BGP Encapsulation Extended Community as
per [EVPN-OVERLAY]. per [EVPN-OVERLAY].
o Route type 5 (IP Prefix route) containing: IPL=24, IP=SN1, o Route type 5 (IP Prefix route) containing: IPL=24, IP=SN1,
ESI=ESI23, GW IP address=0. The Router's MAC Extended ESI=ESI23, GW IP address=0. The Router's MAC Extended
Community defined in [EVPN-INTERSUBNET] is added and carries Community defined in [EVPN-INTERSUBNET] is added and carries
the MAC address (M2) associated to the TS behind which SN1 the MAC address (M2) associated to the TS behind which SN1
seats. sits. M2 may be learned by policy.
(2) NVE3 advertises the following BGP routes for TS3:
o Route type 1 (Ethernet A-D route for EVI-10) containing: (2) NVE3 advertises the following BGP route for TS3 (no AD per-EVI
ESI=ESI23 and the corresponding tunnel information (VNI/VSID route is advertised):
field), as well as the BGP Encapsulation Extended Community.
o Route type 5 (IP Prefix route) containing: IPL=24, IP=SN1, o Route type 5 (IP Prefix route) containing: IPL=24, IP=SN1,
ESI=23, GW IP address=0. The Router's MAC Extended Community ESI=23, GW IP address=0. The Router's MAC Extended Community
is added and carries the MAC address (M3) associated to the TS is added and carries the MAC address (M3) associated to the TS
behind which SN1 seats. behind which SN1 sits. M3 may be learned by policy.
(3) DGW1 and DGW2 import the received routes based on the route- (3) DGW1 and DGW2 import the received routes based on the route-
target: target:
o The tunnel information to get to ESI23 is installed in DGW1 o The tunnel information to get to ESI23 is installed in DGW1
and DGW2. For the VXLAN use case, the VTEP will be derived and DGW2. For the VXLAN use case, the VTEP will be derived
from the Ethernet A-D route BGP next-hop and VNI from the from the Ethernet A-D route BGP next-hop and VNI from the
VNI/VSID field (see [EVPN-OVERLAY]). VNI/VSID field (see [EVPN-OVERLAY]).
o SN1/24 is added to the IP-VRF in DGW1 and DGW2 with overlay o The RT-5 coming from the NVE that advertised the RT-1 is
index ESI23. selected and SN1/24 is added to the IP-VRF in DGW1 and DGW2
with Overlay Index ESI23 and MAC = M2.
(4) When DGW1 receives a packet from the WAN with destination IPx, (4) When DGW1 receives a packet from the WAN with destination IPx,
where IPx belongs to SN1/24: where IPx belongs to SN1/24:
o A destination IP lookup is performed on the DGW1 IP-VRF o A destination IP lookup is performed on the DGW1 IP-VRF
routing table and overlay index=ESI23 is found. Since ESI23 is routing table and Overlay Index=ESI23 is found. Since ESI23 is
an overlay index, a recursive route resolution is required to an Overlay Index, a recursive route resolution is required to
find the egress NVE where ESI23 resides. find the egress NVE where ESI23 resides.
o The IP packet destined to IPx is encapsulated with: o The IP packet destined to IPx is encapsulated with:
. Source inner MAC = IRB1 MAC. . Source inner MAC = IRB1 MAC.
. Destination inner MAC = M2 (this MAC will be obtained . Destination inner MAC = M2 (this MAC will be obtained
from the Router's MAC Extended Community received along from the Router's MAC Extended Community received along
with the RT-5 for SN1). with the RT-5 for SN1).
skipping to change at page 18, line 17 skipping to change at page 20, line 36
(6) If the redundancy protocol running between TS2 and TS3 follows an (6) If the redundancy protocol running between TS2 and TS3 follows an
active/standby model and there is a failure, appointing TS3 as active/standby model and there is a failure, appointing TS3 as
the new active TS for SN1, TS3 will now own the connectivity to the new active TS for SN1, TS3 will now own the connectivity to
SN1 and will signal this new ownership. Upon receiving the new SN1 and will signal this new ownership. Upon receiving the new
owner's notification, NVE3's AC will become active and issue a owner's notification, NVE3's AC will become active and issue a
route type 1 for ESI23, whereas NVE2 will withdraw its Ethernet route type 1 for ESI23, whereas NVE2 will withdraw its Ethernet
A-D route for ESI23. DGW1 and DGW2 will update their tunnel A-D route for ESI23. DGW1 and DGW2 will update their tunnel
information to resolve ESI23. The destination inner MAC will be information to resolve ESI23. The destination inner MAC will be
changed to M3. changed to M3.
5.4 IP-VRF-to-IP-VRF model 4.4 IP-VRF-to-IP-VRF model
This use-case is similar to the scenario described in "IRB forwarding This use-case is similar to the scenario described in "IRB forwarding
on NVEs for Tenant Systems" in [EVPN-INTERSUBNET], however the new on NVEs for Tenant Systems" in [EVPN-INTERSUBNET], however the new
requirement here is the advertisement of IP Prefixes as opposed to requirement here is the advertisement of IP Prefixes as opposed to
only host routes. only host routes.
In the examples described in sections 5.1, 5.2 and 5.3, the MAC-VRF In the examples described in sections 4.1, 4.2 and 4.3, the MAC-VRF
instance can connect IRB interfaces and any other Tenant Systems instance can connect IRB interfaces and any other Tenant Systems
connected to it. EVPN provides connectivity for: connected to it. EVPN provides connectivity for:
1. Traffic destined to the IRB IP interfaces as well as 1. Traffic destined to the IRB or TS IP interfaces as well as
2. Traffic destined to IP subnets seating behind the TS, e.g. SN1 or 2. Traffic destined to IP subnets sitting behind the TS, e.g. SN1 or
SN2. SN2.
In order to provide connectivity for (1), MAC/IP routes (RT-2) are In order to provide connectivity for (1), MAC/IP routes (RT-2) are
needed so that IRB MACs and IPs can be distributed. Connectivity type needed so that IRB or TS MACs and IPs can be distributed.
(2) is accomplished by the exchange of IP Prefix routes (RT-5) for Connectivity type (2) is accomplished by the exchange of IP Prefix
IPs and subnets seating behind certain overlay indexes, e.g. GW IP or routes (RT-5) for IPs and subnets sitting behind certain Overlay
ESI. Indexes, e.g. GW IP or ESI.
In some cases, IP Prefix routes may be advertised for subnets and IPs In some cases, IP Prefix routes may be advertised for subnets and IPs
seating behind an IRB. We refer to this use-case as the "IP-VRF-to- sitting behind an IRB. We refer to this use-case as the "IP-VRF-to-
IP-VRF" model. IP-VRF" model.
[EVPN-INTERSUBNET] defines an asymmetric IRB model and a symmetric [EVPN-INTERSUBNET] defines an asymmetric IRB model and a symmetric
IRB model, based on the required lookups at the ingress and egress IRB model, based on the required lookups at the ingress and egress
NVE: the asymmetric model requires an ip-lookup and a mac-lookup at NVE: the asymmetric model requires an ip-lookup and a mac-lookup at
the ingress NVE, whereas only a mac-lookup is needed at the egress the ingress NVE, whereas only a mac-lookup is needed at the egress
NVE; the symmetric model requires ip and mac lookups at both, ingress NVE; the symmetric model requires ip and mac lookups at both, ingress
and egress NVE. From that perspective, the IP-VRF-to-IP-VRF use-case and egress NVE. From that perspective, the IP-VRF-to-IP-VRF use-case
described in this section is a symmetric IRB model. Note that in an described in this section is a symmetric IRB model.
IP-VRF-to-IP-VRF scenario, a PE may not be configured with any MAC-
VRF for a given tenant, in which case it will only be doing IP
lookups and forwarding for that tenant.
Based on the way the IP-VRFs are interconnected, there are three Note that, in an IP-VRF-to-IP-VRF scenario, out of the many subnets
different IP-VRF-to-IP-VRF scenarios identified and described in this that a tenant may have, it may be the case that only a few are
document: attached to a given NVE/PE's IP-VRF. In order to provide inter-subnet
connectivity among the set of NVE/PEs where the tenant is connected,
a new inter-subnet or core EVI is created on all of them. This core
EVI is instantiated as a core MAC-VRF in each NVE/PE and has a core-
facing IRB interface that connects the core MAC-VRF to the IP-VRF. If
no recursive resolution is needed, the core EVI may not be needed and
the IP-VRFs may be connected directly by Ethernet or IP NVO tunnels.
Depending on the existence and characteristics of the core-facing IRB
interface in the core EVI, there are three different IP-VRF-to-IP-VRF
scenarios identified and described in this document:
1) Interface-less model 1) Interface-less model
2) Interface-full with core-facing IRB model 2) Interface-ful with core-facing IRB model
3) Interface-full with unnumbered core-facing IRB model 3) Interface-ful with unnumbered core-facing IRB model
5.4.1 Interface-less IP-VRF-to-IP-VRF model Inter-subnet IP multicast is outside the scope of this document.
4.4.1 Interface-less IP-VRF-to-IP-VRF model
Figure 6 will be used for the description of this model. Figure 6 will be used for the description of this model.
NVE1(M1) NVE1(M1)
+------------+ +------------+
IP1+----|(MAC-VRF1) | DGW1(M3) IP1+----|(MAC-VRF1) | DGW1(M3)
| \ | +---------+ +--------+ | \ | +---------+ +--------+
| (IP-VRF)|----| |-|(IP-VRF)|----+ | (IP-VRF)|----| |-|(IP-VRF)|----+
| / | | | +--------+ | | / | | | +--------+ |
+---|(MAC-VRF2) | | | _+_ +---|(MAC-VRF2) | | | _+_
| +------------+ | | ( ) | +------------+ | | ( )
SN1| | VXLAN/ | ( WAN ) SN1| | VXLAN/ | ( WAN )--H1
| NVE2(M2) | nvGRE/ | (___) | NVE2(M2) | nvGRE/ | (___)
| +------------+ | MPLS | + | +------------+ | MPLS | +
+---|(MAC-VRF2) | | | DGW2(M4) | +---|(MAC-VRF2) | | | DGW2(M4) |
| \ | | | +--------+ | | \ | | | +--------+ |
| (IP-VRF)|----| |-|(IP-VRF)|----+ | (IP-VRF)|----| |-|(IP-VRF)|----+
| / | +---------+ +--------+ | / | +---------+ +--------+
SN2+----|(MAC-VRF3) | SN2+----|(MAC-VRF3) |
+------------+ +------------+
Figure 6 Interface-less IP-VRF-to-IP-VRF model Figure 6 Interface-less IP-VRF-to-IP-VRF model
In this case, the requirements are the following: In this case:
a) The NVEs and DGWs must provide connectivity between hosts in SN1, a) The NVEs and DGWs must provide connectivity between hosts in SN1,
SN2, IP1 and hosts seating at the other end of the WAN. SN2, IP1 and hosts sitting at the other end of the WAN, for
example, H1. We assume the DGWs import/export IP and/or VPN-IP
routes from/to the WAN.
b) The IP-VRF instances in the NVE/DGWs are directly connected b) The IP-VRF instances in the NVE/DGWs are directly connected
through NVO tunnels, and no IRBs and/or MAC-VRF instances are through NVO tunnels, and no IRBs and/or MAC-VRF instances are
defined at the core. instantiated to connect the IP-VRFs.
c) The solution must provide layer-3 connectivity among the IP-VRFs c) The solution must provide layer-3 connectivity among the IP-VRFs
for Ethernet NVO tunnels, for instance, VXLAN or nvGRE. for Ethernet NVO tunnels, for instance, VXLAN or nvGRE.
d) The solution may provide layer-3 connectivity among the IP-VRFs d) The solution may provide layer-3 connectivity among the IP-VRFs
for IP NVO tunnels, for example, VXLAN GPE (with IP payload). for IP NVO tunnels, for example, VXLAN GPE (with IP payload).
In order to meet the above requirements, the EVPN route type 5 will In order to meet the above requirements, the EVPN route type 5 will
be used to advertise the IP Prefixes, along with the Router's MAC be used to advertise the IP Prefixes, along with the Router's MAC
Extended Community as defined in [EVPN-INTERSUBNET] if the Extended Community as defined in [EVPN-INTERSUBNET] if the
advertising NVE/DGW uses Ethernet NVO tunnels. Each NVE/DGW will advertising NVE/DGW uses Ethernet NVO tunnels. Each NVE/DGW will
advertise an RT-5 for each of its prefixes with the following fields: advertise an RT-5 for each of its prefixes with the following fields:
o RD as per [RFC7432]. o RD as per [RFC7432].
o Eth-Tag ID=0 assuming VLAN-based service. o Eth-Tag ID=0.
o IP address length and IP address, as explained in the previous o IP address length and IP address, as explained in the previous
sections. sections.
o GW IP address= SHOULD be set to 0. o GW IP address=0.
o ESI=0 o ESI=0
o MPLS label or VNI corresponding to the IP-VRF. o MPLS label or VNI corresponding to the IP-VRF.
Each RT-5 will be sent with a route-target identifying the tenant Each RT-5 will be sent with a route-target identifying the tenant
(IP-VRF) and two BGP extended communities: (IP-VRF) and two BGP extended communities:
o The first one is the BGP Encapsulation Extended Community, as o The first one is the BGP Encapsulation Extended Community, as
per [RFC5512], identifying the tunnel type. per [RFC5512], identifying the tunnel type.
skipping to change at page 20, line 47 skipping to change at page 23, line 33
[EVPN-INTERSUBNET] containing the MAC address associated to [EVPN-INTERSUBNET] containing the MAC address associated to
the NVE advertising the route. This MAC address identifies the the NVE advertising the route. This MAC address identifies the
NVE/DGW and MAY be re-used for all the IP-VRFs in the NVE. The NVE/DGW and MAY be re-used for all the IP-VRFs in the NVE. The
Router's MAC Extended Community MUST be sent if the route is Router's MAC Extended Community MUST be sent if the route is
associated to an Ethernet NVO tunnel, for instance, VXLAN. If associated to an Ethernet NVO tunnel, for instance, VXLAN. If
the route is associated to an IP NVO tunnel, for instance the route is associated to an IP NVO tunnel, for instance
VXLAN GPE with IP payload, the Router's MAC Extended Community VXLAN GPE with IP payload, the Router's MAC Extended Community
SHOULD NOT be sent. SHOULD NOT be sent.
The following example illustrates the procedure to advertise and The following example illustrates the procedure to advertise and
forward packets to SN1/24 (ipv4 prefix advertised from NVE1) for forward packets to SN1/24 (ipv4 prefix advertised from NVE1):
VXLAN tunnels:
(1) NVE1 advertises the following BGP route: (1) NVE1 advertises the following BGP route:
o Route type 5 (IP Prefix route) containing: o Route type 5 (IP Prefix route) containing:
. IPL=24, IP=SN1, VNI=10. . IPL=24, IP=SN1, Label=10.
. GW IP= SHOULD be set to 0. . GW IP= SHOULD be set to 0.
. [RFC5512] BGP Encapsulation Extended Community with Tunnel- . [RFC5512] BGP Encapsulation Extended Community.
type=VXLAN.
. Router's MAC Extended Community that contains M1. . Router's MAC Extended Community that contains M1.
. Route-target identifying the tenant (IP-VRF). . Route-target identifying the tenant (IP-VRF).
(2) DGW1 imports the received routes from NVE1: (2) DGW1 imports the received routes from NVE1:
o DGW1 installs SN1/24 in the IP-VRF identified by the RT-5 o DGW1 installs SN1/24 in the IP-VRF identified by the RT-5
route-target. route-target.
o Since GW IP=0 and the VNI is a valid value, DGW1 will use the o Since GW IP=ESI=0, the Label is a non-zero value and the local
VNI and next-hop of the RT-5, as well as the MAC address policy indicates this interface-less model, DGW1 will use the
Label and next-hop of the RT-5, as well as the MAC address
conveyed in the Router's MAC Extended Community (as inner conveyed in the Router's MAC Extended Community (as inner
destination MAC address) to encapsulate the routed IP packets. destination MAC address) to set up the forwarding state and
later encapsulate the routed IP packets.
(3) When DGW1 receives a packet from the WAN with destination IPx, (3) When DGW1 receives a packet from the WAN with destination IPx,
where IPx belongs to SN1/24: where IPx belongs to SN1/24:
o A destination IP lookup is performed on the DGW1 IP-VRF o A destination IP lookup is performed on the DGW1 IP-VRF
routing table. The lookup yields SN1/24. routing table. The lookup yields SN1/24.
o Since the RT-5 for SN1/24 had a GW IP=0 and a valid VNI and o Since the RT-5 for SN1/24 had a GW IP=ESI=0, a non-zero Label
next-hop (used as destination VTEP), DGW1 will not need a and next-hop and the model is interface-less, DGW1 will not
recursive lookup to resolve the route. need a recursive lookup to resolve the route.
o The IP packet destined to IPx is encapsulated with: Source o The IP packet destined to IPx is encapsulated with: Source
inner MAC = DGW1 MAC, Destination inner MAC = M1, Source outer inner MAC = DGW1 MAC, Destination inner MAC = M1, Source outer
IP (source VTEP) = DGW1 IP, Destination outer IP (destination IP (tunnel source IP) = DGW1 IP, Destination outer IP (tunnel
VTEP) = NVE1 IP. destination IP) = NVE1 IP. The Source and Destination inner
MAC addresses are not needed if IP NVO tunnels are used.
(4) When the packet arrives at NVE1: (4) When the packet arrives at NVE1:
o NVE1 will identify the IP-VRF for an IP-lookup based on the o NVE1 will identify the IP-VRF for an IP-lookup based on the
VNI. Label (the Destination inner MAC is not needed to identify the
IP-VRF).
o An IP lookup is performed in the routing context, where SN1 o An IP lookup is performed in the routing context, where SN1
turns out to be a local subnet associated to MAC-VRF2. A turns out to be a local subnet associated to MAC-VRF2. A
subsequent lookup in the ARP table and the MAC-VRF FIB will subsequent lookup in the ARP table and the MAC-VRF FIB will
provide the forwarding information for the packet in MAC-VRF2. provide the forwarding information for the packet in MAC-VRF2.
The implementation of this Interface-less model is REQUIRED. The model described above is called Interface-less model since the
IP-VRFs are connected directly through tunnels and they don't require
those tunnels to be terminated in core MAC-VRFs instead, like in
sections 4.4.2 or 4.4.3. An EVPN IP-VRF-to-IP-VRF implementation is
REQUIRED to support the ingress and egress procedures described in
this section.
5.4.2 Interface-full IP-VRF-to-IP-VRF with core-facing IRB 4.4.2 Interface-ful IP-VRF-to-IP-VRF with core-facing IRB
Figure 7 will be used for the description of this model. Figure 7 will be used for the description of this model.
NVE1 NVE1
+------------+ DGW1 +------------+ DGW1
IP1+----+(MAC-VRF1) | +---------------+ +------------+ IP10+---+(MAC-VRF1) | +---------------+ +------------+
| \ (core) (core) | | \ (core) (core) |
|(IP-VRF)(MAC-VRF) (MAC-VRF)(IP-VRF)|-----+ |(IP-VRF)(MAC-VRF) (MAC-VRF)(IP-VRF)|-----+
| / IRB(IP1/M1) IRB(IP3/M3) | | | / IRB(IP1/M1) IRB(IP3/M3) | |
+---+(MAC-VRF2) | | | +------------+ _+_ +---+(MAC-VRF2) | | | +------------+ _+_
| +------------+ | | ( ) | +------------+ | | ( )
SN1| | VXLAN/ | ( WAN ) SN1| | VXLAN/ | ( WAN )--H1
| NVE2 | nvGRE/ | (___) | NVE2 | nvGRE/ | (___)
| +------------+ | MPLS | DGW2 + | +------------+ | MPLS | DGW2 +
+---+(MAC-VRF2) | | | +------------+ | +---+(MAC-VRF2) | | | +------------+ |
| \ (core) (core) | | | \ (core) (core) | |
|(IP-VRF)(MAC-VRF) (MAC-VRF)(IP-VRF)|-----+ |(IP-VRF)(MAC-VRF) (MAC-VRF)(IP-VRF)|-----+
| / IRB(IP2/M2) IRB(IP4/M4) | | / IRB(IP2/M2) IRB(IP4/M4) |
SN2+----+(MAC-VRF3) | +---------------+ +------------+ SN2+----+(MAC-VRF3) | +---------------+ +------------+
+------------+ +------------+
Figure 7 Interface-full with core-facing IRB model Figure 7 Interface-ful with core-facing IRB model
In this model, the requirements are the following: In this model:
a) As in section 5.4.1, the NVEs and DGWs must provide connectivity a) As in section 4.4.1, the NVEs and DGWs must provide connectivity
between hosts in SN1, SN2, IP1 and hosts seating at the other end between hosts in SN1, SN2, IP1 and hosts sitting at the other end
of the WAN. of the WAN.
b) However, the NVE/DGWs are now connected through Ethernet NVO b) However, the NVE/DGWs are now connected through Ethernet NVO
tunnels terminated in core-MAC-VRF instances. The IP-VRFs use IRB tunnels terminated in core-MAC-VRF instances. The IP-VRFs use IRB
interfaces for their connectivity to the core MAC-VRFs. interfaces for their connectivity to the core MAC-VRFs.
c) Each core-facing IRB has an IP and a MAC address, where the IP c) Each core-facing IRB has an IP and a MAC address, where the IP
address must be reachable from other NVEs or DGWs. address must be reachable from other NVEs or DGWs.
d) The core EVI is composed of the NVE/DGW MAC-VRFs and may contain d) The core EVI is composed of the NVE/DGW MAC-VRFs and may contain
skipping to change at page 23, line 10 skipping to change at page 26, line 5
e) The solution must provide layer-3 connectivity for Ethernet NVO e) The solution must provide layer-3 connectivity for Ethernet NVO
tunnels, for instance, VXLAN or nvGRE. tunnels, for instance, VXLAN or nvGRE.
EVPN type 5 routes will be used to advertise the IP Prefixes, whereas EVPN type 5 routes will be used to advertise the IP Prefixes, whereas
EVPN RT-2 routes will advertise the MAC/IP addresses of each core- EVPN RT-2 routes will advertise the MAC/IP addresses of each core-
facing IRB interface. Each NVE/DGW will advertise an RT-5 for each of facing IRB interface. Each NVE/DGW will advertise an RT-5 for each of
its prefixes with the following fields: its prefixes with the following fields:
o RD as per [RFC7432]. o RD as per [RFC7432].
o Eth-Tag ID=0 assuming VLAN-based service. o Eth-Tag ID=0.
o IP address length and IP address, as explained in the previous o IP address length and IP address, as explained in the previous
sections. sections.
o GW IP address=IRB-IP (this is the overlay index that will be o GW IP address=IRB-IP (this is the Overlay Index that will be
used for the recursive route resolution). used for the recursive route resolution).
o ESI=0 o ESI=0
o MPLS label or VNI corresponding to the IP-VRF. Note that the o Label value SHOULD be zero since the RT-5 route requires a
value SHOULD be zero since the RT-5 route requires a recursive recursive lookup resolution to an RT-2 route. The MPLS label
lookup resolution to an RT-2 route. The MPLS label or VNI to or VNI to be used when forwarding packets will be derived from
be used when forwarding packets will be derived from the RT- the RT-2's MPLS Label1 field. The RT-5's Label field will be
2's MPLS Label1 field. ignored on reception.
Each RT-5 will be sent with a route-target identifying the tenant Each RT-5 will be sent with a route-target identifying the tenant
(IP-VRF). The Router's MAC Extended Community SHOULD NOT be sent in (IP-VRF). The Router's MAC Extended Community SHOULD NOT be sent in
this case. this case.
The following example illustrates the procedure to advertise and The following example illustrates the procedure to advertise and
forward packets to SN1/24 (ipv4 prefix advertised from NVE1) for forward packets to SN1/24 (ipv4 prefix advertised from NVE1):
VXLAN tunnels:
(1) NVE1 advertises the following BGP routes: (1) NVE1 advertises the following BGP routes:
o Route type 5 (IP Prefix route) containing: o Route type 5 (IP Prefix route) containing:
. IPL=24, IP=SN1, VNI= SHOULD be set to 0. . IPL=24, IP=SN1, Label= SHOULD be set to 0.
. GW IP=IP1 (core-facing IRB's IP) . GW IP=IP1 (core-facing IRB's IP)
. Route-target identifying the tenant (IP-VRF). . Route-target identifying the tenant (IP-VRF).
o Route type 2 (MAC/IP route for the core-facing IRB) o Route type 2 (MAC/IP route for the core-facing IRB)
containing: containing:
. ML=48, M=M1, IPL=32, IP=IP1, VNI=10. . ML=48, M=M1, IPL=32, IP=IP1, Label=10.
. A [RFC5512] BGP Encapsulation Extended Community with . A [RFC5512] BGP Encapsulation Extended Community.
Tunnel-type= VXLAN.
. Route-target identifying the tenant. This route-target MAY . Route-target identifying the core MAC-VRF. This route-target
be the same as the one used with the RT-5. MAY be the same as the one used with the RT-5.
(2) DGW1 imports the received routes from NVE1: (2) DGW1 imports the received routes from NVE1:
o DGW1 installs SN1/24 in the IP-VRF identified by the RT-5 o DGW1 installs SN1/24 in the IP-VRF identified by the RT-5
route-target. route-target.
. Since GW IP is different from zero, the GW IP (IP1) will be . Since GW IP is different from zero, the GW IP (IP1) will be
used as the overlay index for the recursive route resolution used as the Overlay Index for the recursive route resolution
to the RT-2 carrying IP1. to the RT-2 carrying IP1.
(3) When DGW1 receives a packet from the WAN with destination IPx, (3) When DGW1 receives a packet from the WAN with destination IPx,
where IPx belongs to SN1/24: where IPx belongs to SN1/24:
o A destination IP lookup is performed on the DGW1 IP-VRF o A destination IP lookup is performed on the DGW1 IP-VRF
routing table. The lookup yields SN1/24, which is associated routing table. The lookup yields SN1/24, which is associated
to the overlay index IP1. The forwarding information is to the Overlay Index IP1. The forwarding information is
derived from the RT-2 received for IP1. derived from the RT-2 received for IP1.
o The IP packet destined to IPx is encapsulated with: Source o The IP packet destined to IPx is encapsulated with: Source
inner MAC = M3, Destination inner MAC = M1, Source outer IP inner MAC = M3, Destination inner MAC = M1, Source outer IP
(source VTEP) = DGW1 IP, Destination outer IP (destination (source VTEP) = DGW1 IP, Destination outer IP (destination
VTEP) = NVE1 IP. VTEP) = NVE1 IP.
(4) When the packet arrives at NVE1: (4) When the packet arrives at NVE1:
o NVE1 will identify the IP-VRF for an IP-lookup based on the o NVE1 will identify the IP-VRF for an IP-lookup based on the
VNI and the inner MAC DA. Label and the inner MAC DA.
o An IP lookup is performed in the routing context, where SN1 o An IP lookup is performed in the routing context, where SN1
turns out to be a local subnet associated to MAC-VRF2. A turns out to be a local subnet associated to MAC-VRF2. A
subsequent lookup in the ARP table and the MAC-VRF FIB will subsequent lookup in the ARP table and the MAC-VRF FIB will
provide the forwarding information for the packet in MAC-VRF2. provide the forwarding information for the packet in MAC-VRF2.
The implementation of the Interface-full with core-facing IRB model The model described above is called 'Interface-ful with core-facing
is REQUIRED. IRB model' since the tunnels connecting the DGWs and NVEs need to be
terminated into the core MAC-VRFs. Those MAC-VRFs are connected to
the IP-VRFs via core-facing IRB interfaces, and that allows the
recursive resolution of RT-5s to GW IP addresses. An EVPN IP-VRF-to-
IP-VRF implementation is REQUIRED to support the ingress and egress
procedures described in this section.
5.4.3 Interface-full IP-VRF-to-IP-VRF with unnumbered core-facing IRB 4.4.3 Interface-ful IP-VRF-to-IP-VRF with unnumbered core-facing IRB
Figure 8 will be used for the description of this model. Note that Figure 8 will be used for the description of this model. Note that
this model is similar to the one described in section 5.4.2, only this model is similar to the one described in section 4.4.2, only
without IP addresses on the core-facing IRB interfaces. without IP addresses on the core-facing IRB interfaces.
NVE1 NVE1
+------------+ DGW1 +------------+ DGW1
IP1+----+(MAC-VRF1) | +---------------+ +------------+ IP1+----+(MAC-VRF1) | +---------------+ +------------+
| \ (core) (core) | | \ (core) (core) |
|(IP-VRF)(MAC-VRF) (MAC-VRF)(IP-VRF)|-----+ |(IP-VRF)(MAC-VRF) (MAC-VRF)(IP-VRF)|-----+
| / IRB(M1)| | IRB(M3) | | | / IRB(M1)| | IRB(M3) | |
+---+(MAC-VRF2) | | | +------------+ _+_ +---+(MAC-VRF2) | | | +------------+ _+_
| +------------+ | | ( ) | +------------+ | | ( )
SN1| | VXLAN/ | ( WAN ) SN1| | VXLAN/ | ( WAN )--H1
| NVE2 | nvGRE/ | (___) | NVE2 | nvGRE/ | (___)
| +------------+ | MPLS | DGW2 + | +------------+ | MPLS | DGW2 +
+---+(MAC-VRF2) | | | +------------+ | +---+(MAC-VRF2) | | | +------------+ |
| \ (core) (core) | | | \ (core) (core) | |
|(IP-VRF)(MAC-VRF) (MAC-VRF)(IP-VRF)|-----+ |(IP-VRF)(MAC-VRF) (MAC-VRF)(IP-VRF)|-----+
| / IRB(M2)| | IRB(M4) | | / IRB(M2)| | IRB(M4) |
SN2+----+(MAC-VRF3) | +---------------+ +------------+ SN2+----+(MAC-VRF3) | +---------------+ +------------+
+------------+ +------------+
Figure 8 Interface-full with unnumbered core-facing IRB model Figure 8 Interface-ful with unnumbered core-facing IRB model
In this model, the requirements are the following: In this model:
a) As in section 5.4.1 and 5.4.2, the NVEs and DGWs must provide a) As in section 4.4.1 and 4.4.2, the NVEs and DGWs must provide
connectivity between hosts in SN1, SN2, IP1 and hosts seating at connectivity between hosts in SN1, SN2, IP1 and hosts sitting at
the other end of the WAN. the other end of the WAN.
b) As in section 5.4.2, the NVE/DGWs are connected through Ethernet b) As in section 4.4.2, the NVE/DGWs are connected through Ethernet
NVO tunnels terminated in core-MAC-VRF instances. The IP-VRFs use NVO tunnels terminated in core-MAC-VRF instances. The IP-VRFs use
IRB interfaces for their connectivity to the core MAC-VRFs. IRB interfaces for their connectivity to the core MAC-VRFs.
c) However, each core-facing IRB has a MAC address only, and no IP c) However, each core-facing IRB has a MAC address only, and no IP
address (that is why the model refers to an 'unnumbered' core- address (that is why the model refers to an 'unnumbered' core-
facing IRB). In this model, there is no need to have IP facing IRB). In this model, there is no need to have IP
reachability to the core-facing IRB interfaces themselves and reachability to the core-facing IRB interfaces themselves and
there is a requirement to save IP addresses on those interfaces. there is a requirement to save IP addresses on those interfaces.
d) As in section 5.4.2, the core EVI is composed of the NVE/DGW MAC- d) As in section 4.4.2, the core EVI is composed of the NVE/DGW MAC-
VRFs and may contain other MAC-VRFs. VRFs and may contain other MAC-VRFs.
e) As in section 5.4.2, the solution must provide layer-3 e) As in section 4.4.2, the solution must provide layer-3
connectivity for Ethernet NVO tunnels, for instance, VXLAN or connectivity for Ethernet NVO tunnels, for instance, VXLAN or
nvGRE. nvGRE.
This model will also make use of the RT-5 recursive resolution. EVPN This model will also make use of the RT-5 recursive resolution. EVPN
type 5 routes will advertise the IP Prefixes along with the Router's type 5 routes will advertise the IP Prefixes along with the Router's
MAC Extended Community used for the recursive lookup, whereas EVPN MAC Extended Community used for the recursive lookup, whereas EVPN
RT-2 routes will advertise the MAC addresses of each core-facing IRB RT-2 routes will advertise the MAC addresses of each core-facing IRB
interface (this time without an IP). Each NVE/DGW will advertise an interface (this time without an IP).
RT-5 for each of its prefixes with the following fields:
o RD as per [RFC7432].
o Eth-Tag ID=0 assuming VLAN-based service.
o IP address length and IP address, as explained in the previous Each NVE/DGW will advertise an RT-5 for each of its prefixes with the
sections. same fields as described in 4.4.2 except for:
o GW IP address= SHOULD be set to 0. o GW IP address= SHOULD be set to 0.
o ESI=0
o MPLS label or VNI corresponding to the IP-VRF. Note that the
value SHOULD be zero since the RT-5 route requires a recursive
lookup resolution to an RT-2 route. The MPLS label or VNI to
be used when forwarding packets will be derived from the RT-
2's MPLS Label1 field.
Each RT-5 will be sent with a route-target identifying the tenant Each RT-5 will be sent with a route-target identifying the tenant
(IP-VRF) and the Router's MAC Extended Community containing the MAC (IP-VRF) and the Router's MAC Extended Community containing the MAC
address associated to core-facing IRB interface. This MAC address MAY address associated to core-facing IRB interface. This MAC address MAY
be re-used for all the IP-VRFs in the NVE. be re-used for all the IP-VRFs in the NVE.
The following example illustrates the procedure to advertise and The example is similar to the one in section 4.4.2:
forward packets to SN1/24 (ipv4 prefix advertised from NVE1) for
VXLAN tunnels:
(1) NVE1 advertises the following BGP routes: (1) NVE1 advertises the following BGP routes:
o Route type 5 (IP Prefix route) containing: o Route type 5 (IP Prefix route) containing the same values as
in the example in section 4.4.2, except for:
. IPL=24, IP=SN1, VNI= SHOULD be set to 0.
. GW IP= SHOULD be set to 0. . GW IP= SHOULD be set to 0.
. Router's MAC Extended Community containing M1 (this will be . Router's MAC Extended Community containing M1 (this will be
used for the recursive lookup to a RT-2). used for the recursive lookup to a RT-2).
. Route-target identifying the tenant (IP-VRF). o Route type 2 (MAC route for the core-facing IRB) with the same
values as in section 4.4.2 except for:
o Route type 2 (MAC route for the core-facing IRB) containing:
. ML=48, M=M1, IPL=0, VNI=10.
. A [RFC5512] BGP Encapsulation Extended Community with
Tunnel-type=VXLAN.
. Route-target identifying the tenant. This route-target MAY . ML=48, M=M1, IPL=0, Label=10.
be the same as the one used with the RT-5.
(2) DGW1 imports the received routes from NVE1: (2) DGW1 imports the received routes from NVE1:
o DGW1 installs SN1/24 in the IP-VRF identified by the RT-5 o DGW1 installs SN1/24 in the IP-VRF identified by the RT-5
route-target. route-target.
. The MAC contained in the Router's MAC Extended Community . The MAC contained in the Router's MAC Extended Community
sent along with the RT-5 (M1) will be used as the overlay sent along with the RT-5 (M1) will be used as the Overlay
index for the recursive route resolution to the RT-2 Index for the recursive route resolution to the RT-2
carrying M1. carrying M1.
(3) When DGW1 receives a packet from the WAN with destination IPx, (3) When DGW1 receives a packet from the WAN with destination IPx,
where IPx belongs to SN1/24: where IPx belongs to SN1/24:
o A destination IP lookup is performed on the DGW1 IP-VRF o A destination IP lookup is performed on the DGW1 IP-VRF
routing table. The lookup yields SN1/24, which is associated routing table. The lookup yields SN1/24, which is associated
to the overlay index M1. The forwarding information is derived to the Overlay Index M1. The forwarding information is derived
from the RT-2 received for M1. from the RT-2 received for M1.
o The IP packet destined to IPx is encapsulated with: Source o The IP packet destined to IPx is encapsulated with: Source
inner MAC = M3, Destination inner MAC = M1, Source outer IP inner MAC = M3, Destination inner MAC = M1, Source outer IP
(source VTEP) = DGW1 IP, Destination outer IP (destination (source VTEP) = DGW1 IP, Destination outer IP (destination
VTEP) = NVE1 IP. VTEP) = NVE1 IP.
(4) When the packet arrives at NVE1: (4) When the packet arrives at NVE1:
o NVE1 will identify the IP-VRF for an IP-lookup based on the o NVE1 will identify the IP-VRF for an IP-lookup based on the
VNI and the inner MAC DA. Label and the inner MAC DA.
o An IP lookup is performed in the routing context, where SN1 o An IP lookup is performed in the routing context, where SN1
turns out to be a local subnet associated to MAC-VRF2. A turns out to be a local subnet associated to MAC-VRF2. A
subsequent lookup in the ARP table and the MAC-VRF FIB will subsequent lookup in the ARP table and the MAC-VRF FIB will
provide the forwarding information for the packet in MAC-VRF2. provide the forwarding information for the packet in MAC-VRF2.
The implementation of the Interface-full with unnumbered core-facing The model described above is called Interface-ful with core-facing
IRB model is OPTIONAL. IRB model (as in section 4.4.2), only this time the core-facing IRB
does not have an IP address. This model is OPTIONAL for an EVPN IP-
VRF-to-IP-VRF implementation.
6. Conclusions 5. Conclusions
An EVPN route (type 5) for the advertisement of IP Prefixes is An EVPN route (type 5) for the advertisement of IP Prefixes is
described in this document. This new route type has a differentiated described in this document. This new route type has a differentiated
role from the RT-2 route and addresses all the Data Center (or NVO- role from the RT-2 route and addresses the Data Center (or NVO-based
based networks in general) inter-subnet connectivity scenarios in networks in general) inter-subnet connectivity scenarios described in
which an IP Prefix advertisement is required. Using this new RT-5, an this document. Using this new RT-5, an IP Prefix may be advertised
IP Prefix may be advertised along with an overlay index that can be a along with an Overlay Index that can be a GW IP address, a MAC or an
GW IP address, a MAC or an ESI, or without an overlay index, in which ESI, or without an Overlay Index, in which case the BGP next-hop will
case the BGP next-hop will point at the egress NVE and the MAC in the point at the egress NVE/ASBR/ABR and the MAC in the Router's MAC
Router's MAC Extended Community will provide the inner MAC Extended Community will provide the inner MAC destination address to
destination address to be used. As discussed throughout the document, be used. As discussed throughout the document, the EVPN RT-2 does not
the EVPN RT-2 does not meet the requirements for all the DC use meet the requirements for all the DC use cases, therefore this EVPN
cases, therefore this EVPN route type 5 is required. route type 5 is required.
The EVPN route type 5 decouples the IP Prefix advertisements from the The EVPN route type 5 decouples the IP Prefix advertisements from the
MAC/IP route advertisements in EVPN, hence: MAC/IP route advertisements in EVPN, hence:
a) Allows the clean and clear advertisements of ipv4 or ipv6 prefixes a) Allows the clean and clear advertisements of ipv4 or ipv6 prefixes
in an NLRI with no MAC addresses in the route key, so that only IP in an NLRI with no MAC addresses.
information is used in BGP route comparisons.
b) Since the route type is different from the MAC/IP Advertisement b) Since the route type is different from the MAC/IP Advertisement
route, the advertisement of prefixes will be excluded from all the route, the current [RFC7432] procedures do not need to be
procedures defined for the advertisement of VM MACs, e.g. MAC modified.
Mobility or aliasing. As a result of that, the current [RFC7432]
procedures do not need to be modified.
c) Allows a flexible implementation where the prefix can be linked to c) Allows a flexible implementation where the prefix can be linked to
different types of overlay indexes: overlay IP address, overlay different types of Overlay Indexes: overlay IP address, overlay
MAC addresses, overlay ESI, underlay IP next-hops, etc. MAC addresses, overlay ESI, underlay BGP next-hops, etc.
d) An EVPN implementation not requiring IP Prefixes can simply d) An EVPN implementation not requiring IP Prefixes can simply
discard them by looking at the route type value. An unknown route discard them by looking at the route type value.
type MUST be ignored by the receiving NVE/PE.
7. Conventions used in this document 6. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [RFC2119]. document are to be interpreted as described in RFC-2119 [RFC2119].
8. Security Considerations 7. Security Considerations
The security considerations discussed in [RFC7432] apply to this The security considerations discussed in [RFC7432] apply to this
document. document.
9. IANA Considerations 8. IANA Considerations
This document requests the allocation of value 5 in the "EVPN Route This document requests the allocation of value 5 in the "EVPN Route
Types" registry defined by [RFC7432] and modification of the registry Types" registry defined by [RFC7432]:
as follows:
Value Description Reference Value Description Reference
5 IP Prefix route [this document] 5 IP Prefix route [this document]
6-255 Unassigned
10. References 9. References
10.1 Normative References 9.1 Normative References
[RFC4364]Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private [RFC4364]Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 2006, Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 2006,
<http://www.rfc-editor.org/info/rfc4364>. <http://www.rfc-editor.org/info/rfc4364>.
[RFC7432]Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., [RFC7432]Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet
VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015, <http://www.rfc- VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015, <http://www.rfc-
editor.org/info/rfc7432>. editor.org/info/rfc7432>.
[RFC7606]Chen, E., Scudder, J., Mohapatra, P., and K. Patel, "Revised
Error Handling for BGP UPDATE Messages", RFC 7606, August 2015,
<http://www.rfc-editor.org/info/rfc7606>.
9.2 Informative References
[EVPN-INTERSUBNET] Sajassi et al., "IP Inter-Subnet Forwarding in [EVPN-INTERSUBNET] Sajassi et al., "IP Inter-Subnet Forwarding in
EVPN", draft-ietf-bess-evpn-inter-subnet-forwarding-03.txt, work in EVPN", draft-ietf-bess-evpn-inter-subnet-forwarding-03.txt, work in
progress, February, 2017 progress, February, 2017
10.2 Informative References
[EVPN-OVERLAY] Sajassi-Drake et al., "A Network Virtualization [EVPN-OVERLAY] Sajassi-Drake et al., "A Network Virtualization
Overlay Solution using EVPN", draft-ietf-bess-evpn-overlay-07.txt, Overlay Solution using EVPN", draft-ietf-bess-evpn-overlay-08.txt,
work in progress, November, 2016 work in progress, March, 2017
11. Acknowledgments 10. Acknowledgments
The authors would like to thank Mukul Katiyar for their valuable The authors would like to thank Mukul Katiyar and Jeffrey Zhang for
feedback and contributions. The following people also helped their valuable feedback and contributions. The following people also
improving this document with their feedback: Tony Przygienda and helped improving this document with their feedback: Tony Przygienda
Thomas Morin. and Thomas Morin. Special THANK YOU to Eric Rosen for his detailed
review, it really helped improve the readability and clarify the
concepts.
12. Contributors 11. Contributors
In addition to the authors listed on the front page, the following In addition to the authors listed on the front page, the following
co-authors have also contributed to this document: co-authors have also contributed to this document:
Senthil Sathappan Senthil Sathappan
Florin Balus Florin Balus
Aldrin Isaac Aldrin Isaac
Senad Palislamovic Senad Palislamovic
13. Authors' Addresses 12. Authors' Addresses
Jorge Rabadan (Editor) Jorge Rabadan (Editor)
Nokia Nokia
777 E. Middlefield Road 777 E. Middlefield Road
Mountain View, CA 94043 USA Mountain View, CA 94043 USA
Email: jorge.rabadan@nokia.com Email: jorge.rabadan@nokia.com
Wim Henderickx Wim Henderickx
Nokia Nokia
Email: wim.henderickx@nokia.com Email: wim.henderickx@nokia.com
 End of changes. 174 change blocks. 
497 lines changed or deleted 580 lines changed or added

This html diff was produced by rfcdiff 1.45. The latest version is available from http://tools.ietf.org/tools/rfcdiff/