draft-ietf-bess-evpn-prefix-advertisement-05.txt   draft-ietf-bess-evpn-prefix-advertisement-06.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: January 19, 2018 July 18, 2017 Expires: April 19, 2018 October 16, 2017
IP Prefix Advertisement in EVPN IP Prefix Advertisement in EVPN
draft-ietf-bess-evpn-prefix-advertisement-05 draft-ietf-bess-evpn-prefix-advertisement-06
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 some connectivity in an MPLS and/or NVO-based network. In some networks,
networks, there is also a need for a dynamic and efficient inter- there is also a need for a dynamic and efficient inter-subnet
subnet connectivity across Tenant Systems and End Devices that can be connectivity across Tenant Systems and End Devices that can be
physical or virtual and do not necessarily participate in dynamic physical or virtual and do not necessarily participate in dynamic
routing protocols. This document defines a new EVPN route type for routing protocols. This document defines a new EVPN route type for
the advertisement of IP Prefixes and explains some use-case examples the advertisement of IP Prefixes and explains some use-case examples
where this new route-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.
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 January 19, 2018. This Internet-Draft will expire on April 16, 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 . . . . . . . . . . . . . . 4 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 . . . . . . . . . 7 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 . . . . . . . . . . . . . . . . . . 9 3.1 IP Prefix Route Encoding . . . . . . . . . . . . . . . . . . 9
3.2 Overlay Indexes and Recursive Lookup Resolution . . . . . . 10 3.2 Overlay Indexes and Recursive Lookup Resolution . . . . . . 10
4. IP Prefix Overlay Index use-cases . . . . . . . . . . . . . . . 13 4. Overlay Index Use-Cases . . . . . . . . . . . . . . . . . . . . 13
4.1 TS IP address Overlay Index use-case . . . . . . . . . . . . 13 4.1 TS IP Address Overlay Index Use-Case . . . . . . . . . . . . 13
4.2 Floating IP Overlay Index use-case . . . . . . . . . . . . . 15 4.2 Floating IP Overlay Index Use-Case . . . . . . . . . . . . . 15
4.3 Bump-in-the-wire use-case . . . . . . . . . . . . . . . . . 17 4.3 Bump-in-the-Wire Use-Case . . . . . . . . . . . . . . . . . 17
4.4 IP-VRF-to-IP-VRF model . . . . . . . . . . . . . . . . . . . 20 4.4 IP-VRF-to-IP-VRF Model . . . . . . . . . . . . . . . . . . . 20
4.4.1 Interface-less IP-VRF-to-IP-VRF model . . . . . . . . . 21 4.4.1 Interface-less IP-VRF-to-IP-VRF Model . . . . . . . . . 21
4.4.2 Interface-ful IP-VRF-to-IP-VRF with core-facing IRB . . 24 4.4.2 Interface-ful IP-VRF-to-IP-VRF with SBD-facing IRB . . . 24
4.4.3 Interface-ful IP-VRF-to-IP-VRF with unnumbered 4.4.3 Interface-ful IP-VRF-to-IP-VRF with Unnumbered
core-facing IRB . . . . . . . . . . . . . . . . . . . . 27 SBD-facing IRB . . . . . . . . . . . . . . . . . . . . . 27
5. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 30 5. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6. Conventions used in this document . . . . . . . . . . . . . . . 31 6. Conventions used in this document . . . . . . . . . . . . . . . 31
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 31 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 31
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 31 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 31
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 31 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 31
9.1 Normative References . . . . . . . . . . . . . . . . . . . . 31 9.1 Normative References . . . . . . . . . . . . . . . . . . . . 31
9.2 Informative References . . . . . . . . . . . . . . . . . . . 31 9.2 Informative References . . . . . . . . . . . . . . . . . . . 31
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 32 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 32
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 32 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 32
12. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 32 12. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 32
skipping to change at page 3, line 36 skipping to change at page 3, line 36
ND: Neighbor Discovery Protocol. ND: Neighbor Discovery Protocol.
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 tunnels with Ethernet payload. Examples of this type of tunnels
are 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). with IP payload (no MAC header in the payload).
EVI: EVPN Instance spanning the NVE and PE devices that are EVI: EVPN Instance spanning the NVE/PE devices that are participating
participating on that EVPN. on that EVPN.
MAC-VRF: A Virtual Routing and Forwarding table for Media Access MAC-VRF: A Virtual Routing and Forwarding table for Media Access
Control (MAC) addresses on an NVE/PE, as per [RFC7432]. Control (MAC) addresses on an NVE/PE, as per [RFC7432].
BD: Broadcast Domain. As per [RFC7432], an EVI consists of a single BD: Broadcast Domain. As per [RFC7432], an EVI consists of a single
or multiple BDs. or multiple BDs. In case of VLAN-bundle and VLAN-based service
models (see [RFC7432]), a BD is equivalent to an EVI. In case of
VLAN-aware bundle service model, an EVI contains multiple BDs.
Also, in this document, BD and subnet are equivalent terms.
BT: Bridge Table. The instantiation of a BD in a MAC-VRF. 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 IP-VRF: A VPN Routing and Forwarding table for IP routes on an
NVE/PE, similar to the VRF concept defined in [RFC4364], however, NVE/PE. The IP routes could be populated by EVPN and IP-VPN
in this document, the IP routes are always populated by the EVPN address families.
address family.
IRB: Integrated Routing and Bridging interface. It connects an IP-VRF IRB: Integrated Routing and Bridging interface. It connects an IP-VRF
to a BT. In order to simplify the explanation, this document to a BD (or subnet).
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 SBD: Supplementary Broadcast Domain. A BD that does not have any ACs,
only IRB interfaces, and it is used to provide connectivity among
all the IP-VRFs of the tenant. The SBD is only required in IP-VRF-
to-IP-VRF use-cases (see section 4.4.).
2. Introduction and Problem Statement
Inter-subnet connectivity is used for certain tenants within the Data Inter-subnet connectivity is used for certain tenants within the Data
Center. [EVPN-INTERSUBNET] defines some fairly common inter-subnet Center. [EVPN-INTERSUBNET] defines some fairly common inter-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 achieve this, 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
skipping to change at page 4, line 32 skipping to change at page 4, line 35
[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. Interoperability between EVPN and L3VPN [RFC4364] IP Prefix Prefixes. Interoperability between EVPN and L3VPN [RFC4364] IP Prefix
routes is out of the scope of this document. 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 a virtual system identified by MAC and maybe IP addresses, and
MAC-VRF by an Attachment Circuit, the following considerations apply: connected to a BD 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
sitting 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.
skipping to change at page 6, line 7 skipping to change at page 6, line 7
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.
Figure 1 illustrates some of the examples described above. Figure 1 illustrates some of the examples described above.
NVE1 NVE1
+-----------+ +-----------+
TS1(VM)--|(MAC-VRF10)|-----+ TS1(VM)--| (BD-10) |-----+
IP1/M1 +-----------+ | DGW1 IP1/M1 +-----------+ | DGW1
+---------+ +-------------+ +---------+ +-------------+
| |----|(MAC-VRF10) | | |----| (BD-10) |
SN1---+ NVE2 | | | IRB1\ | SN1---+ NVE2 | | | IRB1\ |
| +-----------+ | | | (IP-VRF)|---+ | +-----------+ | | | (IP-VRF)|---+
SN2---TS2(VA)--|(MAC-VRF10)|-| | +-------------+ _|_ SN2---TS2(VA)--| (BD-10) |-| | +-------------+ _|_
| IP2/M2 +-----------+ | VXLAN/ | ( ) | IP2/M2 +-----------+ | VXLAN/ | ( )
IP4---+ <-+ | nvGRE | DGW2 ( WAN ) IP4---+ <-+ | nvGRE | DGW2 ( WAN )
| | | +-------------+ (___) | | | +-------------+ (___)
vIP23 (floating) | |----|(MAC-VRF10) | | vIP23 (floating) | |----| (BD-10) | |
| +---------+ | IRB2\ | | | +---------+ | IRB2\ | |
SN1---+ <-+ NVE3 | | | | (IP-VRF)|---+ SN1---+ <-+ NVE3 | | | | (IP-VRF)|---+
| IP3/M3 +-----------+ | | | +-------------+ | IP3/M3 +-----------+ | | | +-------------+
SN3---TS3(VA)--|(MAC-VRF10)|---+ | | SN3---TS3(VA)--| (BD-10) |---+ | |
| +-----------+ | | | +-----------+ | |
IP5---+ | | IP5---+ | |
| | | |
NVE4 | | NVE5 +--SN5 NVE4 | | NVE5 +--SN5
+---------------------+ | | +-----------+ | +---------------------+ | | +-----------+ |
IP6------|(MAC-VRF1) | | +-|(MAC-VRF10)|--TS4(VA)--SN6 IP6------| (BD-1) | | +-| (BD-10) |--TS4(VA)--SN6
| \ | | +-----------+ | | \ | | +-----------+ |
| (IP-VRF) |--+ ESI4 +--SN7 | (IP-VRF) |--+ ESI4 +--SN7
| / \IRB3 | | / \IRB3 |
|---|(MAC-VRF2)(MAC-VRF10)| |---| (BD-2) (BD-10) |
SN4| +---------------------+ SN4| +---------------------+
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 BD for a
particular tenant. EVI-10 is comprised of the collection of MAC-VRF10 particular tenant. BD-10 is comprised of the collection of BD
instances defined in all the NVEs. All the hosts connected to EVI-10 instances defined in all the NVEs. All the hosts connected to BD-10
belong to the same IP subnet. The hosts connected to EVI-10 are belong to the same IP subnet. The hosts connected to BD-10 are listed
listed below: below:
o TS1 is a VM that generates/receives traffic from/to IP1, where IP1 o TS1 is a VM that generates/receives traffic from/to IP1, where IP1
belongs to the EVI-10 subnet. belongs to the BD-10 subnet.
o TS2 and TS3 are Virtual Appliances (VA) that generate/receive
traffic from/to the subnets and hosts sitting behind them (SN1,
SN2, SN3, IP4 and IP5). Their IP addresses (IP2 and IP3) belong to
the EVI-10 subnet and they can also generate/receive traffic. When
these VAs receive packets destined to their own MAC addresses (M2
and M3) they will route the packets to the proper subnet or host.
These VAs do not support routing protocols to advertise the subnets o TS2 and TS3 are Virtual Appliances (VA) that send/receive traffic
connected to them and can move to a different server and NVE when from/to the subnets and hosts sitting behind them (SN1, SN2, SN3,
the Cloud Management System decides to do so. These VAs may also IP4 and IP5). Their IP addresses (IP2 and IP3) belong to the BD-10
support redundancy mechanisms for some subnets, similar to VRRP, subnet and they can also generate/receive traffic. When these VAs
where a floating IP is owned by the master VA and only the master receive packets destined to their own MAC addresses (M2 and M3)
VA forwards traffic to a given subnet. E.g.: vIP23 in figure 1 is a they will route the packets to the 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 floating IP that can be owned by TS2 or TS3 depending on who the
master is. Only the master will forward traffic to SN1. master is. Only the master will forward traffic to SN1.
o Integrated Routing and Bridging interfaces IRB1, IRB2 and IRB3 have o Integrated Routing and Bridging interfaces IRB1, IRB2 and IRB3 have
their own IP addresses that belong to the EVI-10 subnet too. These their own IP addresses that belong to the BD-10 subnet too. These
IRB interfaces connect the EVI-10 subnet to Virtual Routing and IRB interfaces connect the BD-10 subnet to Virtual Routing and
Forwarding (IP-VRF) instances that can route the traffic to other Forwarding (IP-VRF) instances that can route the traffic to other
connected subnets for the same tenant (within the DC or at the subnets for the same tenant (within the DC or at the other end of
other end of the WAN). the WAN).
o TS4 is a layer-2 VA that provides connectivity to subnets SN5, SN6 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 and SN7, but does not have an IP address itself in the BD-10. TS4
is connected to a physical port on NVE5 assigned to Ethernet is connected to a physical port on NVE5 assigned to Ethernet
Segment Identifier 4. 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 a) MUST be advertised from the NVEs (since VAs and VMs do not
participate in dynamic 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, a MAC address or an ESI. An Overlay Index 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 is a next-hop that requires a recursive resolution and it is
described in section 3.2. 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 MAC address of either M2 or
Figure 1) and MAC associated to it, otherwise the solution gets M3", otherwise the solution gets highly inefficient and does not
highly inefficient and does not scale. 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
skipping to change at page 8, line 32 skipping to change at page 8, line 32
o In MAC/IP routes, the MAC information is part of the NLRI, so if IP o In MAC/IP routes, the MAC information is part of the NLRI, so if IP
Prefixes were to be advertised using MAC/IP routes, the MAC Prefixes were to be advertised using MAC/IP routes, the MAC
information would always be present and part of the route key. information would always be present and part of the route key.
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) |
+-----------------------------------+ +-----------------------------------+
skipping to change at page 9, line 22 skipping to change at page 9, line 22
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, as specified by Section 5.4 in [RFC7606]. 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:
+---------------------------------------+ +---------------------------------------+
| RD (8 octets) | | RD (8 octets) |
+---------------------------------------+ +---------------------------------------+
|Ethernet Segment Identifier (10 octets)| |Ethernet Segment Identifier (10 octets)|
+---------------------------------------+ +---------------------------------------+
| Ethernet Tag ID (4 octets) | | Ethernet Tag ID (4 octets) |
skipping to change at page 10, line 15 skipping to change at page 10, line 15
o The IP Prefix Length can be set to a value between 0 and 32 (bits) o The IP Prefix Length can be set to a value between 0 and 32 (bits)
for ipv4 and between 0 and 128 for ipv6, and specifies the number for ipv4 and between 0 and 128 for ipv6, and specifies the number
of bits in the Prefix. of bits in the Prefix.
o The IP Prefix will be a 32 or 128-bit field (ipv4 or ipv6). The 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 size of this field does not depend on the value of the IP Prefix
Length field. Length field.
o The GW IP (Gateway IP Address) will be a 32 or 128-bit field (ipv4 o The GW IP (Gateway IP Address) will be a 32 or 128-bit field (ipv4
or ipv6), and will encode an overlay IP index for the IP Prefixes. or ipv6), and will encode an IP address as an overlay index for the
The GW IP field SHOULD be zero if it is not used as an Overlay IP Prefixes. The GW IP field SHOULD be zero if it is not used as an
Index. Refer to section 3.2 for the definition and use of the Overlay Index. Refer to section 3.2 for the definition and use of
Overlay Index. the Overlay Index.
o The MPLS Label field is encoded as 3 octets, where the high-order o The MPLS Label field is encoded as 3 octets, where the high-order
20 bits contain the label value. When sending, the label value 20 bits contain the label value. When sending, the label value
SHOULD be zero to indicate that recursive resolution is needed. If SHOULD be zero if recursive resolution based on overlay index is
the received MPLS Label value is zero, the route MUST contain an used. If the received MPLS Label value is zero, the route MUST
Overlay Index and the ingress NVE/PE MUST do recursive resolution contain an Overlay Index and the ingress NVE/PE MUST do recursive
to find the egress NVE/PE. If the received Label value is non-zero, resolution to find the egress NVE/PE. If the received Label value
the route will not be used for recursive resolution unless a local is non-zero, the route will not be used for recursive resolution
policy says so. unless a local policy says so.
o The total route length will indicate the type of prefix (ipv4 or o The total route length will indicate the type of prefix (ipv4 or
ipv6) and the type of GW IP address (ipv4 or ipv6). Note that the ipv6) and the type of GW IP address (ipv4 or ipv6). Note that the
IP Prefix + the GW IP should have a length of either 64 or 256 IP Prefix + the GW IP should have a length of either 64 or 256
bits, but never 160 bits (ipv4 and ipv6 mixed values are not bits, but never 160 bits (ipv4 and ipv6 mixed values are not
allowed). allowed).
The RD, Eth-Tag ID, IP Prefix Length and IP Prefix will be part of The RD, Eth-Tag ID, IP Prefix Length and IP Prefix will be part of
the route key used by BGP to compare routes. The rest of the fields the route key used by BGP to compare routes. The rest of the fields
will not be part of the route key. will not be part of the route key.
An IP Prefix Route MAY be sent along with a Router's MAC Extended
Community (defined in [EVPN-INTERSUBNET]).
3.2 Overlay Indexes and Recursive Lookup Resolution 3.2 Overlay Indexes and Recursive Lookup Resolution
RT-5 routes support recursive lookup resolution through the use of RT-5 routes support recursive lookup resolution through the use of
Overlay Indexes as follows: Overlay Indexes as follows:
o An Overlay Index can be an ESI, IP address in the address space of 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 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 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 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 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 to forward the packets. It is important to note that recursive
resolution of the Overlay Index applies upon installation into an resolution of the Overlay Index applies upon installation into an
IP-VRF, and not upon BGP propagation. Also, as a result of the IP-VRF, and not upon BGP propagation (for instance, on an ASBR).
recursive resolution, the egress NVE/PE is not necessarily the same Also, as a result of the recursive resolution, the egress NVE/PE is
NVE that originated the RT-5. not necessarily the same NVE that originated the RT-5.
o The Overlay Index is indicated along with the RT-5 in the ESI o The Overlay Index is indicated along with the RT-5 in the ESI
field, GW IP field or Router's MAC Extended Community, depending on field, GW IP field or Router's MAC Extended Community, depending on
whether the IP Prefix next-hop is an ESI, IP address or MAC address whether the IP Prefix next-hop is an ESI, IP address or MAC address
in the tenant space. The Overlay Index for a given IP Prefix is set 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 by local policy at the NVE that originates an RT-5 for that IP
Prefix (typically managed by the Cloud Management System). Prefix (typically managed by the Cloud Management System).
o In order to enable the recursive lookup resolution at the ingress o In order to enable the recursive lookup resolution at the ingress
NVE, an NVE that is a possible egress NVE for a given Overlay Index NVE, an NVE that is a possible egress NVE for a given Overlay Index
skipping to change at page 11, line 39 skipping to change at page 11, line 42
the IP address field of its NLRI. the IP address field of its NLRI.
. If the RT-5 specifies a MAC address as the Overlay Index, . If the RT-5 specifies a MAC address as the Overlay Index,
recursive resolution can only be done if the NVE has received and recursive resolution can only be done if the NVE has received and
installed an RT-2 (MAC/IP route) specifying that MAC address in installed an RT-2 (MAC/IP route) specifying that MAC address in
the MAC address field of its NLRI. the MAC address field of its NLRI.
Note that the RT-1 or RT-2 routes needed for the recursive Note that the RT-1 or RT-2 routes needed for the recursive
resolution may arrive before or after the given RT-5 route. resolution may arrive before or after the given RT-5 route.
o Irrespective of the recursive resolution, if there is no IGP or BGP o Irrespective of the recursive resolution, if there is no IGP or BGP
route to the BGP next-hop of an RT-5, BGP may fail to install the route to the BGP next-hop of an RT-5, BGP should fail to install
RT-5 even if the Overlay Index can be resolved. the RT-5 even if the Overlay Index can be resolved.
o The ESI and GW IP fields MAY both be zero, however they MUST NOT o The ESI and GW IP fields MAY both be zero, however they MUST NOT
both be non-zero at the same time. A route containing a non-zero GW both be non-zero at the same time. A route containing a non-zero GW
IP and a non-zero ESI (at the same time) will be treated as- IP and a non-zero ESI (at the same time) will be treated as-
withdraw. withdraw.
The indirection provided by the Overlay Index and its recursive The indirection provided by the Overlay Index and its recursive
lookup resolution is required to achieve fast convergence in case of lookup resolution is required to achieve fast convergence in case of
a failure of the object represented by the Overlay Index. For a failure of the object represented by the Overlay Index (see the
instance: in Figure 1, let's assume NVE2/NVE3 advertise 1k RT-5 example described in section 2.2).
routes associated to the floating IP address (GWIP=vIP23) and NVE2
advertises an RT-2 claiming the ownership of the floating IP, i.e.
NVE2 encodes vIP23 and M2 in the 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 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).
Table 1 shows the different RT-5 field combinations allowed by this Table 1 shows the different RT-5 field combinations allowed by this
specification and what Overlay Index must be used by the receiving 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 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 receiving NVE/PE will not perform any recursive resolution, and the
actual next-hop is given by the RT-5's BGP next-hop. actual next-hop is given by the RT-5's BGP next-hop.
+----------+----------+----------+------------+----------------+ +----------+----------+----------+------------+----------------+
| ESI | GW-IP | MAC* | Label | Overlay Index | | ESI | GW-IP | MAC* | Label | Overlay Index |
|--------------------------------------------------------------| |--------------------------------------------------------------|
skipping to change at page 13, line 21 skipping to change at page 13, line 21
| 4.4 | IP-VRF-to-IP-VRF | GW IP, MAC or None | | 4.4 | IP-VRF-to-IP-VRF | GW IP, MAC or None |
+---------+---------------------+----------------------------+ +---------+---------------------+----------------------------+
Table 2 - Use-cases and Overlay Indexes for Recursive Resolution Table 2 - Use-cases and Overlay Indexes for Recursive Resolution
The above use-cases are representative of the different Overlay The above use-cases are representative of the different Overlay
Indexes supported by RT-5 (GW IP, ESI, MAC or None). Any other use- Indexes supported by RT-5 (GW IP, ESI, MAC or None). Any other use-
case using a given Overlay Index, SHOULD follow the procedures case using a given Overlay Index, SHOULD follow the procedures
described in this document for the same Overlay Index. described in this document for the same Overlay Index.
4. IP Prefix Overlay Index use-cases 4. Overlay Index Use-Cases
This section describes some use-cases for the Overlay Index types. This section describes some use-cases for the Overlay Index types
used with the IP Prefix route.
4.1 TS IP address Overlay Index use-case 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 sitting 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)--| (BD-10) |-| |----| (BD-10) |
| 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 +-----------+ | |----| (BD-10) | |
SN3---TS3(VA)--|(MAC-VRF10)|-| | | IRB2\ | | SN3---TS3(VA)--| (BD-10) |-| | | 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 sitting 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 participate in dynamic DGW2 are running BGP EVPN. TS2 and TS3 do not participate in dynamic
routing protocols, and they only have a static route to forward the routing protocols, and they only have a static route to forward the
traffic to the WAN. traffic to the WAN. We assume SN1/24 is dual-homed to NVE2 and NVE3.
In this case, a GW IP is used as an Overlay Index. Although a 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 different Overlay Index type could have been used, this use-case
assumes that the operator knows the VA's IP addresses beforehand, 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. 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 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 with the RT-5s. The NVEs know the GW IP to be used for a given Prefix
by policy. by policy.
(1) NVE2 advertises the following BGP routes on behalf of TS2: (1) NVE2 advertises the following BGP routes on behalf of TS2:
skipping to change at page 14, line 37 skipping to change at page 14, line 38
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 BD-10 route-target in DGW1 and DGW2, the MAC/IP
MAC/IP route is imported and M2 is added to the MAC-VRF10 route is imported and M2 is added to the BD-10 along with its
along with its corresponding tunnel information. For instance, corresponding tunnel information. For instance, if VXLAN is
if VXLAN is used, the VTEP will be derived from the MAC/IP used, the VTEP will be derived from the MAC/IP route BGP next-
route BGP next-hop and VNI from the MPLS Label1 field. IP2 - hop and VNI from the MPLS Label1 field. IP2 - M2 is added to
M2 is added to the ARP table. Similarly, M3 is added to MAC- the ARP table. Similarly, M3 is added to BD-10 and IP3 - M3 to
VRF10 and IP3 - M3 to the ARP table. the ARP table.
o Based on the MAC-VRF10 route-target in DGW1 and DGW2, the IP o Based on the BD-10 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. We VRF with Overlay Index IP2 pointing at the local BD-10. In
assume the RT-5 from NVE2 is preferred over the RT-5 from this example, we assume the RT-5 from NVE2 is preferred over
NVE3. Should ECMP be enabled in the IP-VRF and both routes the RT-5 from NVE3. If both routes were equally preferable and
equally preferable, SN1/24 would also be added to the routing ECMP enabled, SN1/24 would also be added to the routing table
table with Overlay Index IP3. 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 BD FIB (e.g. remote VTEP
VTEP and VNI for the VXLAN case). 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.
. Destination inner MAC = M2. . Destination inner MAC = M2.
. Tunnel information provided by the MAC-VRF (VNI, VTEP IPs . Tunnel information provided by the BD (VNI, VTEP IPs and
and MACs for the VXLAN case). MACs for the VXLAN case).
(5) When the packet arrives at NVE2: (5) When the packet arrives at NVE2:
o Based on the tunnel information (VNI for the VXLAN case), the o Based on the tunnel information (VNI for the VXLAN case), the
MAC-VRF10 context is identified for a MAC lookup. BD-10 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) 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.
4.2 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)--| (BD-10) |-| |----| (BD-10) |
| 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 +-----------+ | |----| (BD-10) | |
+---TS3(VA)--|(MAC-VRF10)|-| | | IRB2\ | | +---TS3(VA)--| (BD-10) |-| | | 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 use-case, a GW IP is used as an Overlay Index for the same 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 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: 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:
skipping to change at page 16, line 49 skipping to change at page 16, line 50
(2) NVE3 advertises the following BGP route for TS3 (it does not (2) NVE3 advertises the following BGP route for TS3 (it does not
advertise an RT-2 for IP23/M3): 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. The prefix and GW IP are learned by ESI=0, GW IP address=IP23. The prefix and GW IP are learned by
policy. 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 BD-10 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 M2 in the local MAC-VRF10. index IP23 pointing at M2 in the local BD-10.
(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 BD (remote VTEP and VNI
VNI for the VXLAN case). 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.
. Destination inner MAC = M2. . Destination inner MAC = M2.
. Tunnel information provided by the MAC-VRF FIB (VNI, VTEP . Tunnel information provided by the BD FIB (VNI, VTEP IPs
IPs and MACs for the VXLAN case). and MACs for the VXLAN case).
(5) When the packet arrives at NVE2: (5) When the packet arrives at NVE2:
o Based on the tunnel information (VNI for the VXLAN case), the o Based on the tunnel information (VNI for the VXLAN case), the
MAC-VRF10 context is identified for a MAC lookup. BD-10 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 and NVE2 will withdraw the RT-2 issue a route type 2 for M3-IP23 and NVE2 will withdraw the RT-2
for M2-IP23. DGW1 and DGW2 will update their ARP tables with the for M2-IP23. DGW1 and DGW2 will update their ARP tables with the
new MAC resolving the floating IP. No changes are made in the IP- new MAC resolving the floating IP. No changes are made in the IP-
VRF routing table. VRF routing table.
4.3 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. In this use-case, TS2 and TS3 Prefix route that carries a subnet SN1. In this use-case, TS2 and TS3
are layer-2 VA devices without any IP address that can be included as are layer-2 VA devices without any IP address that can be included as
an Overlay Index in the GW IP field of the IP Prefix route. Their MAC an Overlay Index in the GW IP field of the IP Prefix route. Their MAC
addresses are M2 and M3 respectively and are connected to EVI-10. addresses are M2 and M3 respectively and are connected to BD-10. Note
Note that IRB1 and IRB2 (in DGW1 and DGW2 respectively) have IP that IRB1 and IRB2 (in DGW1 and DGW2 respectively) have IP addresses
addresses in a subnet different than SN1. in a subnet different than SN1.
NVE2 DGW1 NVE2 DGW1
M2 +-----------+ +---------+ +-------------+ M2 +-----------+ +---------+ +-------------+
+---TS2(VA)--|(MAC-VRF10)|-| |----|(MAC-VRF10) | +---TS2(VA)--| (BD-10) |-| |----| (BD-10) |
| ESI23 +-----------+ | | | IRB1\ | | ESI23 +-----------+ | | | IRB1\ |
| + | | | (IP-VRF)|---+ | + | | | (IP-VRF)|---+
| | | | +-------------+ _|_ | | | | +-------------+ _|_
SN1 | | VXLAN/ | ( ) SN1 | | VXLAN/ | ( )
| | | nvGRE | DGW2 ( WAN ) | | | nvGRE | DGW2 ( WAN )
| + NVE3 | | +-------------+ (___) | + NVE3 | | +-------------+ (___)
| ESI23 +-----------+ | |----|(MAC-VRF10) | | | ESI23 +-----------+ | |----| (BD-10) | |
+---TS3(VA)--|(MAC-VRF10)|-| | | IRB2\ | | +---TS3(VA)--| (BD-10) |-| | | IRB2\ | |
M3 +-----------+ +---------+ | (IP-VRF)|---+ M3 +-----------+ +---------+ | (IP-VRF)|---+
+-------------+ +-------------+
Figure 5 Bump-in-the-wire use-case Figure 5 Bump-in-the-wire use-case
Since neither TS2 nor TS3 can participate in any dynamic routing Since neither TS2 nor TS3 can participate in any dynamic routing
protocol and have no IP address assigned, there are two potential protocol and have no IP address assigned, there are two potential
Overlay Index types that can be used when advertising SN1: Overlay Index types that can be used when advertising SN1:
a) an ESI, i.e. ESI23, that can be provisioned on the attachment a) an ESI, i.e. ESI23, that can be provisioned on the attachment
skipping to change at page 19, line 9 skipping to change at page 19, line 10
The model supports VA redundancy in a similar way as the one 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, 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 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 the MAC advertisement route to advertise the location of the Overlay
Index. The procedure is explained below: Index. The procedure is explained below:
(1) Assuming TS2 is the active TS in ESI23, NVE2 advertises the (1) Assuming TS2 is the active TS in ESI23, NVE2 advertises the
following BGP routes: following BGP routes:
o Route type 1 (Ethernet A-D route for EVI-10) containing: o Route type 1 (Ethernet A-D route for BD-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
sits. M2 may be learned by policy. sits. M2 may be learned by policy.
skipping to change at page 20, line 7 skipping to change at page 20, line 7
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). Note that the Router's MAC
Extended Community is used in this case to carry the TS'
MAC address, as opposed to the NVE/PE's MAC address.
. Tunnel information for the NVO tunnel is provided by the . Tunnel information for the NVO tunnel is provided by the
Ethernet A-D route per-EVI for ESI23 (VNI and VTEP IP for Ethernet A-D route per-EVI for ESI23 (VNI and VTEP IP for
the VXLAN case). the VXLAN case).
(5) When the packet arrives at NVE2: (5) When the packet arrives at NVE2:
o Based on the tunnel demultiplexer information (VNI for the o Based on the tunnel demultiplexer information (VNI for the
VXLAN case), the MAC-VRF10 context is identified for a MAC VXLAN case), the BD-10 context is identified for a MAC lookup
lookup (assuming MAC disposition model) or the VNI MAY (assuming MAC disposition model) or the VNI MAY directly
directly identify the egress interface (for a label or VNI identify the egress interface (for a label or VNI disposition
disposition model). model).
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) or a VNI lookup (assuming MAC forwarding on the egress NVE) or a VNI lookup
(in case of VNI forwarding), the packet is forwarded to TS2, (in case of VNI forwarding), the packet is forwarded to TS2,
where it will be forwarded to SN1. where it will be forwarded to SN1.
(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.
4.4 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 4.1, 4.2 and 4.3, the MAC-VRF In the examples described in sections 4.1, 4.2 and 4.3, the BD
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 or TS IP interfaces as well as 1. Traffic destined to the IRB or TS IP interfaces as well as
2. Traffic destined to IP subnets sitting 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 or TS MACs and IPs can be distributed. needed so that IRB or TS MACs and IPs can be distributed.
Connectivity type (2) is accomplished by the exchange of IP Prefix Connectivity type (2) is accomplished by the exchange of IP Prefix
routes (RT-5) for IPs and subnets sitting behind certain Overlay routes (RT-5) for IPs and subnets sitting behind certain Overlay
Indexes, e.g. GW IP or ESI. Indexes, e.g. GW IP or ESI or TS MAC.
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
sitting 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. described in this section is a symmetric IRB model.
Note that, in an IP-VRF-to-IP-VRF scenario, out of the many subnets Note that, in an IP-VRF-to-IP-VRF scenario, out of the many subnets
that a tenant may have, it may be the case that only a few are that a tenant may have, it may be the case that only a few are
attached to a given NVE/PE's IP-VRF. In order to provide inter-subnet 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, 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 a new "Supplementary Broadcast Domain" (SBD) is created on all of
EVI is instantiated as a core MAC-VRF in each NVE/PE and has a core- them. This SBD is instantiated as a regular BD (with no ACs) in each
facing IRB interface that connects the core MAC-VRF to the IP-VRF. If NVE/PE and has a IRB interfaces that connect the SBD to the IP-VRF.
no recursive resolution is needed, the core EVI may not be needed and If no recursive resolution is needed, the SBD may not be needed and
the IP-VRFs may be connected directly by Ethernet or IP NVO tunnels. the IP-VRFs may be connected directly by Ethernet or IP NVO tunnels.
Depending on the existence and characteristics of the core-facing IRB Depending on the existence and characteristics of the SBD and IRB
interface in the core EVI, there are three different IP-VRF-to-IP-VRF interfaces for the IP-VRFs, there are three different IP-VRF-to-IP-
scenarios identified and described in this document: VRF scenarios identified and described in this document:
1) Interface-less model 1) Interface-less model: no SBD and no overlay indexes required.
2) Interface-ful with core-facing IRB model 2) Interface-ful with SBD-facing IRB model: it requires SBD, as well
3) Interface-ful with unnumbered core-facing IRB model as GW IP addresses as overlay indexes.
3) Interface-ful with unnumbered SBD-facing IRB model: it requires
SBD, as well as MAC addresses as overlay indexes.
Inter-subnet IP multicast is outside the scope of this document. Inter-subnet IP multicast is outside the scope of this document.
4.4.1 Interface-less IP-VRF-to-IP-VRF model 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+----| (BD-1) | DGW1(M3)
| \ | +---------+ +--------+ | \ | +---------+ +--------+
| (IP-VRF)|----| |-|(IP-VRF)|----+ | (IP-VRF)|----| |-|(IP-VRF)|----+
| / | | | +--------+ | | / | | | +--------+ |
+---|(MAC-VRF2) | | | _+_ +---| (BD-2) | | | _+_
| +------------+ | | ( ) | +------------+ | | ( )
SN1| | VXLAN/ | ( WAN )--H1 SN1| | VXLAN/ | ( WAN )--H1
| NVE2(M2) | nvGRE/ | (___) | NVE2(M2) | nvGRE/ | (___)
| +------------+ | MPLS | + | +------------+ | MPLS | +
+---|(MAC-VRF2) | | | DGW2(M4) | +---| (BD-2) | | | DGW2(M4) |
| \ | | | +--------+ | | \ | | | +--------+ |
| (IP-VRF)|----| |-|(IP-VRF)|----+ | (IP-VRF)|----| |-|(IP-VRF)|----+
| / | +---------+ +--------+ | / | +---------+ +--------+
SN2+----|(MAC-VRF3) | SN2+----| (BD-3) |
+------------+ +------------+
Figure 6 Interface-less IP-VRF-to-IP-VRF model Figure 6 Interface-less IP-VRF-to-IP-VRF model
In this case: 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 sitting at the other end of the WAN, for 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 example, H1. We assume the DGWs import/export IP and/or VPN-IP
routes from/to the WAN. 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 BD instances are
instantiated to connect the IP-VRFs. 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
skipping to change at page 24, line 35 skipping to change at page 24, line 35
destination IP) = NVE1 IP. The Source and Destination inner destination IP) = NVE1 IP. The Source and Destination inner
MAC addresses are not needed if IP NVO tunnels are used. 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
Label (the Destination inner MAC is not needed to identify the Label (the Destination inner MAC is not needed to identify the
IP-VRF). 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 BD-2. A
subsequent lookup in the ARP table and the MAC-VRF FIB will subsequent lookup in the ARP table and the BD FIB will provide
provide the forwarding information for the packet in MAC-VRF2. the forwarding information for the packet in BD-2.
The model described above is called Interface-less model since the The model described above is called Interface-less model since the
IP-VRFs are connected directly through tunnels and they don't require IP-VRFs are connected directly through tunnels and they don't require
those tunnels to be terminated in core MAC-VRFs instead, like in those tunnels to be terminated in core BDs instead, like in sections
sections 4.4.2 or 4.4.3. An EVPN IP-VRF-to-IP-VRF implementation is 4.4.2 or 4.4.3. An EVPN IP-VRF-to-IP-VRF implementation is REQUIRED
REQUIRED to support the ingress and egress procedures described in to support the ingress and egress procedures described in this
this section. section.
4.4.2 Interface-ful IP-VRF-to-IP-VRF with core-facing IRB 4.4.2 Interface-ful IP-VRF-to-IP-VRF with SBD-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
IP10+---+(MAC-VRF1) | +---------------+ +------------+ IP10+---+(BD-1) | +---------------+ +------------+
| \ (core) (core) | | \ | | | | |
|(IP-VRF)(MAC-VRF) (MAC-VRF)(IP-VRF)|-----+ |(IP-VRF)-(SBD)| |(SBD)-(IP-VRF)|-----+
| / IRB(IP1/M1) IRB(IP3/M3) | | | / IRB(IP1/M1) IRB(IP3/M3) | |
+---+(MAC-VRF2) | | | +------------+ _+_ +---+(BD-2) | | | +------------+ _+_
| +------------+ | | ( ) | +------------+ | | ( )
SN1| | VXLAN/ | ( WAN )--H1 SN1| | VXLAN/ | ( WAN )--H1
| NVE2 | nvGRE/ | (___) | NVE2 | nvGRE/ | (___)
| +------------+ | MPLS | DGW2 + | +------------+ | MPLS | DGW2 +
+---+(MAC-VRF2) | | | +------------+ | +---+(BD-2) | | | +------------+ |
| \ (core) (core) | | | \ | | | | | |
|(IP-VRF)(MAC-VRF) (MAC-VRF)(IP-VRF)|-----+ |(IP-VRF)-(SBD)| |(SBD)-(IP-VRF)|-----+
| / IRB(IP2/M2) IRB(IP4/M4) | | / IRB(IP2/M2) IRB(IP4/M4) |
SN2+----+(MAC-VRF3) | +---------------+ +------------+ SN2+----+(BD-3) | +---------------+ +------------+
+------------+ +------------+
Figure 7 Interface-ful with core-facing IRB model Figure 7 Interface-ful with core-facing IRB model
In this model: In this model:
a) As in section 4.4.1, 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 sitting 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 the SBD instance. The IP-VRFs use IRB
interfaces for their connectivity to the core MAC-VRFs. interfaces for their connectivity to the SBD.
c) Each core-facing IRB has an IP and a MAC address, where the IP c) Each SBD-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 SBD is attached to all the NVE/DGWs in the tenant domain BDs.
other MAC-VRFs without IRB interfaces. Those non-IRB MAC-VRFs will
typically connect TSes that need layer-3 connectivity to remote
subnets.
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 SBD-
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. 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 Label value SHOULD be zero since the RT-5 route requires a o Label value SHOULD be zero since the RT-5 route requires a
recursive lookup resolution to an RT-2 route. The MPLS label recursive lookup resolution to an RT-2 route. It is ignored on
or VNI to be used when forwarding packets will be derived from reception, and, when forwarding packets, the MPLS label or VNI
the RT-2's MPLS Label1 field. The RT-5's Label field will be from the RT-2's MPLS Label1 field is used.
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): forward packets to SN1/24 (ipv4 prefix advertised from NVE1):
(1) NVE1 advertises the following BGP routes: (1) NVE1 advertises the following BGP routes:
skipping to change at page 26, line 45 skipping to change at page 26, line 42
. 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, Label=10. . ML=48, M=M1, IPL=32, IP=IP1, Label=10.
. A [RFC5512] BGP Encapsulation Extended Community. . A [RFC5512] BGP Encapsulation Extended Community.
. Route-target identifying the core MAC-VRF. This route-target . Route-target identifying the SBD. This route-target MAY be
MAY be the same as the one used with the RT-5. 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.
skipping to change at page 27, line 28 skipping to change at page 27, line 25
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
Label 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 BD-2. A
subsequent lookup in the ARP table and the MAC-VRF FIB will subsequent lookup in the ARP table and the BD FIB will provide
provide the forwarding information for the packet in MAC-VRF2. the forwarding information for the packet in BD-2.
The model described above is called 'Interface-ful with core-facing The model described above is called 'Interface-ful with SBD-facing
IRB model' since the tunnels connecting the DGWs and NVEs need to be 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 terminated into the SBD. The SBD is connected to the IP-VRFs via
the IP-VRFs via core-facing IRB interfaces, and that allows the core-facing IRB interfaces, and that allows the recursive resolution
recursive resolution of RT-5s to GW IP addresses. An EVPN IP-VRF-to- of RT-5s to GW IP addresses. An EVPN IP-VRF-to-IP-VRF implementation
IP-VRF implementation is REQUIRED to support the ingress and egress is REQUIRED to support the ingress and egress procedures described in
procedures described in this section. this section.
4.4.3 Interface-ful IP-VRF-to-IP-VRF with unnumbered core-facing IRB 4.4.3 Interface-ful IP-VRF-to-IP-VRF with Unnumbered SBD-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 4.4.2, 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 SBD-facing IRB interfaces.
NVE1 NVE1
+------------+ DGW1 +------------+ DGW1
IP1+----+(MAC-VRF1) | +---------------+ +------------+ IP1+----+(BD-1) | +---------------+ +------------+
| \ (core) (core) | | \ | | | | |
|(IP-VRF)(MAC-VRF) (MAC-VRF)(IP-VRF)|-----+ |(IP-VRF)-(SBD)| (SBD)-(IP-VRF) |-----+
| / IRB(M1)| | IRB(M3) | | | / IRB(M1)| | IRB(M3) | |
+---+(MAC-VRF2) | | | +------------+ _+_ +---+(BD-2) | | | +------------+ _+_
| +------------+ | | ( ) | +------------+ | | ( )
SN1| | VXLAN/ | ( WAN )--H1 SN1| | VXLAN/ | ( WAN )--H1
| NVE2 | nvGRE/ | (___) | NVE2 | nvGRE/ | (___)
| +------------+ | MPLS | DGW2 + | +------------+ | MPLS | DGW2 +
+---+(MAC-VRF2) | | | +------------+ | +---+(BD-2) | | | +------------+ |
| \ (core) (core) | | | \ | | | | | |
|(IP-VRF)(MAC-VRF) (MAC-VRF)(IP-VRF)|-----+ |(IP-VRF)-(SBD)| (SBD)-(IP-VRF) |-----+
| / IRB(M2)| | IRB(M4) | | / IRB(M2)| | IRB(M4) |
SN2+----+(MAC-VRF3) | +---------------+ +------------+ SN2+----+(BD-3) | +---------------+ +------------+
+------------+ +------------+
Figure 8 Interface-ful with unnumbered core-facing IRB model Figure 8 Interface-ful with unnumbered core-facing IRB model
In this model: In this model:
a) As in section 4.4.1 and 4.4.2, 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 sitting 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 4.4.2, 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 the SBD instance. The IP-VRFs use IRB
IRB interfaces for their connectivity to the core MAC-VRFs. interfaces for their connectivity to the SBD.
c) However, each core-facing IRB has a MAC address only, and no IP c) However, each SBD-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' SBD-
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 SBD-facing IRB interfaces themselves and there
there is a requirement to save IP addresses on those interfaces. is a requirement to save IP addresses on those interfaces.
d) As in section 4.4.2, the core EVI is composed of the NVE/DGW MAC- d) As in section 4.4.2, the SBD is composed of all the NVE/DGW BDs of
VRFs and may contain other MAC-VRFs. the tenant that need inter-subnet-forwarding.
e) As in section 4.4.2, 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 SBD-facing IRB
interface (this time without an IP). interface (this time without an IP).
Each NVE/DGW will advertise an RT-5 for each of its prefixes with the Each NVE/DGW will advertise an RT-5 for each of its prefixes with the
same fields as described in 4.4.2 except for: 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.
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 SBD-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 example is similar to the one in section 4.4.2: The example is similar to the one in section 4.4.2:
(1) NVE1 advertises the following BGP routes: (1) NVE1 advertises the following BGP routes:
o Route type 5 (IP Prefix route) containing the same values as o Route type 5 (IP Prefix route) containing the same values as
in the example in section 4.4.2, except for: in the example in section 4.4.2, except for:
. GW IP= SHOULD be set to 0. . GW IP= SHOULD be set to 0.
skipping to change at page 30, line 14 skipping to change at page 30, line 14
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
Label 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 BD-2. A
subsequent lookup in the ARP table and the MAC-VRF FIB will subsequent lookup in the ARP table and the BD FIB will provide
provide the forwarding information for the packet in MAC-VRF2. the forwarding information for the packet in BD-2.
The model described above is called Interface-ful with core-facing The model described above is called Interface-ful with SBD-facing IRB
IRB model (as in section 4.4.2), only this time the core-facing IRB model (as in section 4.4.2), only this time the SBD-facing IRB does
does not have an IP address. This model is OPTIONAL for an EVPN IP- not have an IP address. This model is OPTIONAL for an EVPN IP-VRF-to-
VRF-to-IP-VRF implementation. IP-VRF implementation.
5. 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 the Data Center (or NVO-based role from the RT-2 route and addresses the Data Center (or NVO-based
networks in general) inter-subnet connectivity scenarios described in networks in general) inter-subnet connectivity scenarios described in
this document. Using this new RT-5, an IP Prefix may be advertised this document. Using this new RT-5, an IP Prefix may be advertised
along with an Overlay Index that can be a GW IP address, a MAC or an along with an Overlay Index that can be a GW IP address, a MAC or an
ESI, or without an Overlay Index, in which case the BGP next-hop will ESI, or without an Overlay Index, in which case the BGP next-hop will
skipping to change at page 30, line 49 skipping to change at page 30, line 49
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 an NLRI with no MAC addresses.
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 current [RFC7432] procedures do not need to be route, the current [RFC7432] procedures do not need to be
modified. 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/Underlay Indexes: overlay IP address,
MAC addresses, overlay ESI, underlay BGP next-hops, etc. overlay 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. discard them by looking at the route type value.
6. 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].
 End of changes. 104 change blocks. 
237 lines changed or deleted 235 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/