draft-ietf-bess-evpn-etree-13.txt   draft-ietf-bess-evpn-etree-14.txt 
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Intended Status: Standards Track Cisco Intended Status: Standards Track Cisco
Updates: 7385 J. Drake Updates: 7385 J. Drake
Juniper Juniper
J. Uttaro J. Uttaro
ATT ATT
S. Boutros S. Boutros
VMware VMware
J. Rabadan J. Rabadan
Nokia Nokia
Expires: February 28, 2018 August 28, 2017 Expires: April 28, 2018 October 28, 2017
E-TREE Support in EVPN & PBB-EVPN E-TREE Support in EVPN & PBB-EVPN
draft-ietf-bess-evpn-etree-13 draft-ietf-bess-evpn-etree-14
Abstract Abstract
The Metro Ethernet Forum (MEF) has defined a rooted-multipoint The Metro Ethernet Forum (MEF) has defined a rooted-multipoint
Ethernet service known as Ethernet Tree (E-Tree). A solution Ethernet service known as Ethernet Tree (E-Tree). A solution
framework for supporting this service in MPLS networks is described framework for supporting this service in MPLS networks is described
in RFC7387 ("A Framework for Ethernet-Tree (E-Tree) Service over a in RFC7387 ("A Framework for Ethernet-Tree (E-Tree) Service over a
Multiprotocol Label Switching (MPLS) Network"). This document Multiprotocol Label Switching (MPLS) Network"). This document
discusses how those functional requirements can be met with a discusses how those functional requirements can be met with a
solution based on RFC7432, BGP MPLS Based Ethernet VPN (EVPN), with solution based on RFC7432, BGP MPLS Based Ethernet VPN (EVPN), with
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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 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Specification of Requirements . . . . . . . . . . . . . . . 4 1.1 Specification of Requirements . . . . . . . . . . . . . . . 4
1.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 5
2 E-Tree Scenarios . . . . . . . . . . . . . . . . . . . . . . . 5 2 E-Tree Scenarios . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 Scenario 1: Leaf or Root Site(s) per PE . . . . . . . . . . 5 2.1 Scenario 1: Leaf or Root Site(s) per PE . . . . . . . . . . 6
2.2 Scenario 2: Leaf or Root Site(s) per AC . . . . . . . . . . 6 2.2 Scenario 2: Leaf or Root Site(s) per AC . . . . . . . . . . 6
2.3 Scenario 3: Leaf or Root Site(s) per MAC Address . . . . . . 8 2.3 Scenario 3: Leaf or Root Site(s) per MAC Address . . . . . . 8
3 Operation for EVPN . . . . . . . . . . . . . . . . . . . . . . . 9 3 Operation for EVPN . . . . . . . . . . . . . . . . . . . . . . . 9
3.1 Known Unicast Traffic . . . . . . . . . . . . . . . . . . . 9 3.1 Known Unicast Traffic . . . . . . . . . . . . . . . . . . . 9
3.2 Broadcast, Unkonwn, and Multicast (BUM) Traffic . . . . . . 10 3.2 Broadcast, Unkonwn, and Multicast (BUM) Traffic . . . . . . 10
3.2.1 BUM Traffic Originated from a Single-homed Site on a 3.2.1 BUM Traffic Originated from a Single-homed Site on a
Leaf AC . . . . . . . . . . . . . . . . . . . . . . . . 11 Leaf AC . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.2 BUM Traffic Originated from a Single-homed Site on a 3.2.2 BUM Traffic Originated from a Single-homed Site on a
Root AC . . . . . . . . . . . . . . . . . . . . . . . . 11 Root AC . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.3 BUM Traffic Originated from a Multi-homed Site on a 3.2.3 BUM Traffic Originated from a Multi-homed Site on a
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4 Operation for PBB-EVPN . . . . . . . . . . . . . . . . . . . . . 13 4 Operation for PBB-EVPN . . . . . . . . . . . . . . . . . . . . . 13
4.1 Known Unicast Traffic . . . . . . . . . . . . . . . . . . . 14 4.1 Known Unicast Traffic . . . . . . . . . . . . . . . . . . . 14
4.2 Broadcast, Unkonwn, and Multicast (BUM) Traffic . . . . . . 14 4.2 Broadcast, Unkonwn, and Multicast (BUM) Traffic . . . . . . 14
4.3 E-Tree without MAC Learning . . . . . . . . . . . . . . . . 15 4.3 E-Tree without MAC Learning . . . . . . . . . . . . . . . . 15
5 BGP Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . 15 5 BGP Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.1 E-Tree Extended Community . . . . . . . . . . . . . . . . . 15 5.1 E-Tree Extended Community . . . . . . . . . . . . . . . . . 15
5.2 PMSI Tunnel Attribute . . . . . . . . . . . . . . . . . . . 17 5.2 PMSI Tunnel Attribute . . . . . . . . . . . . . . . . . . . 17
6 Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . 18 6 Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . 18
7 Security Considerations . . . . . . . . . . . . . . . . . . . . 18 7 Security Considerations . . . . . . . . . . . . . . . . . . . . 18
8 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 18 8 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 18
8.1 Considerations for PMSI Tunnel Types . . . . . . . . . . . . 18 8.1 Considerations for PMSI Tunnel Types . . . . . . . . . . . . 19
9 References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 9 References . . . . . . . . . . . . . . . . . . . . . . . . . . 19
9.1 Normative References . . . . . . . . . . . . . . . . . . . 19 9.1 Normative References . . . . . . . . . . . . . . . . . . . 19
9.2 Informative References . . . . . . . . . . . . . . . . . . 20 9.2 Informative References . . . . . . . . . . . . . . . . . . 20
Appendix-A . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Appendix-A . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21
1 Introduction 1 Introduction
The Metro Ethernet Forum (MEF) has defined a rooted-multipoint The Metro Ethernet Forum (MEF) has defined a rooted-multipoint
Ethernet service known as Ethernet Tree (E-Tree) [MEF6.1]. In an E- Ethernet service known as Ethernet Tree (E-Tree) [MEF6.1]. In an E-
Tree service, a customer site that is typically represented by an Tree service, a customer site that is typically represented by an
Attachment Circuits (AC) (e.g., an Ethernet tag but may also be Attachment Circuits (AC) (e.g., a 802.1Q VLAN tag but may also be
represented by a MAC address) is labeled as either a Root or a Leaf represented by a MAC address) is labeled as either a Root or a Leaf
site. Root sites can communicate with all other customer sites (both site. Root sites can communicate with all other customer sites (both
Root and Leaf sites). However, Leaf sites can communicate with Root Root and Leaf sites). However, Leaf sites can communicate with Root
sites but not with other Leaf sits. In this document unless sites but not with other Leaf sits. In this document unless
explicitly mentioned otherwise, a site is always represented by an explicitly mentioned otherwise, a site is always represented by an
AC. AC.
[RFC7387] describes a solution framework for supporting E-Tree [RFC7387] describes a solution framework for supporting E-Tree
service in MPLS networks. The document identifies the functional service in MPLS networks. The document identifies the functional
components of an overall solution to emulate E-Tree services in MPLS components of an overall solution to emulate E-Tree services in MPLS
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[RFC7432] defines EVPN, a solution for multipoint L2VPN services with [RFC7432] defines EVPN, a solution for multipoint L2VPN services with
advanced multi-homing capabilities, using BGP for distributing advanced multi-homing capabilities, using BGP for distributing
customer/client MAC address reach-ability information over the customer/client MAC address reach-ability information over the
MPLS/IP network. [RFC7623] combines the functionality of EVPN with MPLS/IP network. [RFC7623] combines the functionality of EVPN with
[802.1ah] Provider Backbone Bridging (PBB) for MAC address [802.1ah] Provider Backbone Bridging (PBB) for MAC address
scalability. scalability.
This document discusses how the functional requirements for E-Tree This document discusses how the functional requirements for E-Tree
service can be met with a solution based on (PBB-)EVPN (i.e., service can be met with a solution based on (PBB-)EVPN (i.e.,
[RFC7432] and [RFC7623]) with some extensions and how such a solution [RFC7432] and [RFC7623]) with some extensions to their procedures and
can offer a more efficient implementation of these functions than BGP attributes. Such (PBB-)EVPN based solution can offer a more
that of RFC7796, E-Tree Support in Virtual Private LAN Service efficient implementation of these functions than that of RFC7796, E-
(VPLS). Since this document specifies a solution based on [RFC7432], Tree Support in Virtual Private LAN Service (VPLS). This efficiency
it requires the readers to have the knowledge of [RFC7432] as is achieved by performing filtering of unicast traffic at the ingress
PE nodes as opposed to egress filtering where the traffic is sent
through the network and gets filtered and discarded at the egress PE
nodes. The details of this ingress filtering is described in section
3.1. Since this document specifies a solution based on [RFC7432], it
requires the readers to have the knowledge of [RFC7432] as
prerequisite. This document makes use of the most significant bit of prerequisite. This document makes use of the most significant bit of
the "Tunnel Type" field (in PMSI Tunnel Attribute) governed by the the "Tunnel Type" field (in PMSI Tunnel Attribute) governed by the
IANA registry created by RFC7385, and hence updates RFC7385 IANA registry created by RFC7385, and hence updates RFC7385
accordingly. Section 2 discusses E-Tree scenarios. Section 3 and 4 accordingly. Section 2 discusses E-Tree scenarios. Section 3 and 4
describe E-Tree solutions for EVPN and PBB-EVPN respectively, and describe E-Tree solutions for EVPN and PBB-EVPN respectively, and
section 5 covers BGP encoding for E-Tree solutions. section 5 covers BGP encoding for E-Tree solutions.
1.1 Specification of Requirements 1.1 Specification of Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
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- Either Leaf or Root site(s) per Attachment Circuit (AC) - Either Leaf or Root site(s) per Attachment Circuit (AC)
- Either Leaf or Root site(s) per MAC address - Either Leaf or Root site(s) per MAC address
2.1 Scenario 1: Leaf or Root Site(s) per PE 2.1 Scenario 1: Leaf or Root Site(s) per PE
In this scenario, a PE may receive traffic from either Root ACs or In this scenario, a PE may receive traffic from either Root ACs or
Leaf ACs for a given MAC-VRF/bridge table, but not both. In other Leaf ACs for a given MAC-VRF/bridge table, but not both. In other
words, a given EVPN Instance (EVI) on a Provider Edge (PE) device is words, a given EVPN Instance (EVI) on a Provider Edge (PE) device is
either associated with root(s) or leaf(s). The PE may have both Root either associated with Root(s) or Leaf(s). The PE may have both Root
and Leaf ACs albeit for different EVIs. and Leaf ACs albeit for different EVIs.
+---------+ +---------+ +---------+ +---------+
| PE1 | | PE2 | | PE1 | | PE2 |
+---+ | +---+ | +------+ | +---+ | +---+ +---+ | +---+ | +------+ | +---+ | +---+
|CE1+---AC1----+--+ | | | MPLS | | | +--+----AC2-----+CE2| |CE1+---AC1----+--+ | | | MPLS | | | +--+----AC2-----+CE2|
+---+ (Root) | |MAC| | | /IP | | |MAC| | (Leaf) +---+ +---+ (Root) | |MAC| | | /IP | | |MAC| | (Leaf) +---+
| |VRF| | | | | |VRF| | | |VRF| | | | | |VRF| |
| | | | | | | | | | +---+ | | | | | | | | | | +---+
| | | | | | | | +--+----AC3-----+CE3| | | | | | | | | +--+----AC3-----+CE3|
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Leaf site(s) only imports the Root RT. Leaf site(s) only imports the Root RT.
For this scenario, if it is desired to use only a single RT per EVI For this scenario, if it is desired to use only a single RT per EVI
(just like E-LAN services in [RFC7432]), then the approach B in (just like E-LAN services in [RFC7432]), then the approach B in
scenario 2 (described below) needs to be used. scenario 2 (described below) needs to be used.
2.2 Scenario 2: Leaf or Root Site(s) per AC 2.2 Scenario 2: Leaf or Root Site(s) per AC
In this scenario, a PE can receive traffic from both Root ACs and In this scenario, a PE can receive traffic from both Root ACs and
Leaf ACs for a given EVI. In other words, a given EVI on a PE can be Leaf ACs for a given EVI. In other words, a given EVI on a PE can be
associated with both root(s) and leaf(s). associated with both Root(s) and Leaf(s).
+---------+ +---------+ +---------+ +---------+
| PE1 | | PE2 | | PE1 | | PE2 |
+---+ | +---+ | +------+ | +---+ | +---+ +---+ | +---+ | +------+ | +---+ | +---+
|CE1+-----AC1----+--+ | | | | | | +--+---AC2--+CE2| |CE1+-----AC1----+--+ | | | | | | +--+---AC2--+CE2|
+---+ (Leaf) | |MAC| | | MPLS | | |MAC| | (Leaf) +---+ +---+ (Leaf) | |MAC| | | MPLS | | |MAC| | (Leaf) +---+
| |VRF| | | /IP | | |VRF| | | |VRF| | | /IP | | |VRF| |
| | | | | | | | | | +---+ | | | | | | | | | | +---+
| | | | | | | | +--+---AC3--+CE3| | | | | | | | | +--+---AC3--+CE3|
| +---+ | +------+ | +---+ | (Root) +---+ | +---+ | +------+ | +---+ | (Root) +---+
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two approaches for such coloring: two approaches for such coloring:
A) To always use two RTs (one to designate Leaf RT and another for A) To always use two RTs (one to designate Leaf RT and another for
Root RT) Root RT)
B) To allow for a single RT be used per EVI just like [RFC7432] and B) To allow for a single RT be used per EVI just like [RFC7432] and
thus color MAC addresses via a "color" flag in a new extended thus color MAC addresses via a "color" flag in a new extended
community as detailed in section 5.1. community as detailed in section 5.1.
Approach (A) would require the same data plane enhancements as Approach (A) would require the same data plane enhancements as
approach (B) if MAC-VRF/bridge tables used per broadcast domain approach (B) if MAC-VRF and bridge tables used per VLAN, are to
(e.g., VLAN) are to remain consistent with [RFC7432] (section 6). In remain consistent with [RFC7432] (section 6). In order to avoid data-
order to avoid data-plane enhancements for approach (A), multiple plane enhancements for approach (A), multiple bridge tables per VLAN
bridge tables per VLAN may be considered; however, this has major may be considered; however, this has major drawbacks as described in
drawbacks as described in appendix-A and thus is not recommended. appendix-A and thus is not recommended.
Given that both approaches (A) and (B) would require exact same data- Given that both approaches (A) and (B) would require the same data-
plane enhancements, approach (B) is chosen here in order to allow for plane enhancements, approach (B) is chosen here in order to allow for
RT usage consistent with baseline EVPN [RFC7432] and for better RT usage consistent with baseline EVPN [RFC7432] and for better
generality. It should be noted that if one wants to use RT constrain generality. It should be noted that if one wants to use RT
in order to avoid MAC advertisements associated with a Leaf AC to PEs constraints in order to avoid MAC advertisements associated with a
with only Leaf ACs, then two RTs (one for Root and another for Leaf) Leaf AC to PEs with only Leaf ACs, then two RTs (one for Root and
can still be used with approach (B); however, in such applications another for Leaf) can still be used with approach (B); however, in
Leaf/Root RTs will be used to constrain MAC advertisements and they such applications Leaf/Root RTs will be used to constrain MAC
are not used to color the MAC routes for ingress filtering - i.e., in advertisements and they are not used to color the MAC routes for
approach (B), the coloring is always done via the new extended ingress filtering - i.e., in approach (B), the coloring is always
community. done via the new extended community.
For this scenario, if for a given EVI, significant number of PEs have If, for a given EVI, a significant number of PEs have both Leaf and
both Leaf and Root sites attached, even though they may start as Root sites attached (even though they may start as Root-only or Leaf-
Root-only or Leaf-only PEs, then a single RT per EVI should be used. only PEs), then a single RT per EVI should be used. The reason for
The reason for such recommendation is to alleviate the configuration such recommendation is to alleviate the configuration overhead
overhead associated with using two RTs per EVI at the expense of associated with using two RTs per EVI at the expense of having some
having some unwanted MAC addresses on the Leaf-only PEs. unwanted MAC addresses on the Leaf-only PEs.
2.3 Scenario 3: Leaf or Root Site(s) per MAC Address 2.3 Scenario 3: Leaf or Root Site(s) per MAC Address
In this scenario, a customer Root or Leaf site is represented by a In this scenario, a customer Root or Leaf site is represented by a
MAC address and a PE may receive traffic from both Root AND Leaf MAC address and a PE may receive traffic from both Root AND Leaf
sites on a single Attachment Circuit (AC) of an EVI. This scenario is sites on a single Attachment Circuit (AC) of an EVI. This scenario is
not covered in either [RFC7387] or [MEF6.1]; however, it is covered not covered in either [RFC7387] or [MEF6.1]; however, it is covered
in this document for the sake of completeness. In this scenario, in this document for the sake of completeness. In this scenario,
since an AC carries traffic from both Root and Leaf sites, the since an AC carries traffic from both Root and Leaf sites, the
granularity at which Root or Leaf sites are identified is on a per granularity at which Root or Leaf sites are identified is on a per
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approach across all the above three scenarios and the corresponding approach across all the above three scenarios and the corresponding
solution is detailed in the following sections. solution is detailed in the following sections.
3 Operation for EVPN 3 Operation for EVPN
[RFC7432] defines the notion of Ethernet Segment Identifier (ESI) [RFC7432] defines the notion of Ethernet Segment Identifier (ESI)
MPLS label used for split-horizon filtering of BUM traffic at the MPLS label used for split-horizon filtering of BUM traffic at the
egress PE. Such egress filtering capabilities can be leveraged in egress PE. Such egress filtering capabilities can be leveraged in
provision of E-Tree services as it will be seen shortly for BUM provision of E-Tree services as it will be seen shortly for BUM
traffic. For know unicast traffic, additional extensions to [RFC7432] traffic. For know unicast traffic, additional extensions to [RFC7432]
is needed (i.e., a new BGP Extended Community for leaf indication is needed (i.e., a new BGP Extended Community for Leaf indication
described in section 5.1) in order to enable ingress filtering as described in section 5.1) in order to enable ingress filtering as
described in detail in the following sections. described in detail in the following sections.
3.1 Known Unicast Traffic 3.1 Known Unicast Traffic
Since in EVPN, MAC learning is performed in control plane via Since in EVPN, MAC learning is performed in the control plane via
advertisement of BGP routes, the filtering needed by E-Tree service advertisement of BGP routes, the filtering needed by E-Tree service
for known unicast traffic can be performed at the ingress PE, thus for known unicast traffic can be performed at the ingress PE, thus
providing very efficient filtering and avoiding sending known unicast providing very efficient filtering and avoiding sending known unicast
traffic over MPLS/IP core to be filtered at the egress PE as done in traffic over the MPLS/IP core to be filtered at the egress PE as done
traditional E-Tree solutions - i.e., E-Tree for VPLS [RFC7796]. in traditional E-Tree solutions - i.e., E-Tree for VPLS [RFC7796].
To provide such ingress filtering for known unicast traffic, a PE To provide such ingress filtering for known unicast traffic, a PE
MUST indicate to other PEs what kind of sites (root or leaf) its MAC MUST indicate to other PEs what kind of sites (Root or Leaf) its MAC
addresses are associated with. This is done by advertising a Leaf addresses are associated with. This is done by advertising a Leaf
indication flag (via an Extended Community) along with each of its indication flag (via an Extended Community) along with each of its
MAC/IP Advertisement routes learned from a Leaf site. The lack of MAC/IP Advertisement routes learned from a Leaf site. The lack of
such flag indicates that the MAC address is associated with a root such flag indicates that the MAC address is associated with a Root
site. This scheme applies to all scenarios described in section 2. site. This scheme applies to all scenarios described in section 2.
Tagging MAC addresses with a Leaf indication enables remote PEs to Tagging MAC addresses with a Leaf indication enables remote PEs to
perform ingress filtering for known unicast traffic - i.e., on the perform ingress filtering for known unicast traffic - i.e., on the
ingress PE, the MAC destination address lookup yields, in addition to ingress PE, the MAC destination address lookup yields, in addition to
the forwarding adjacency, a flag which indicates whether the target the forwarding adjacency, a flag which indicates whether the target
MAC is associated with a Leaf site or not. The ingress PE cross- MAC is associated with a Leaf site or not. The ingress PE cross-
checks this flag with the status of the originating AC, and if both checks this flag with the status of the originating AC, and if both
are leafs, then the packet is not forwarded. are leafs, then the packet is not forwarded.
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(e.g., non-static MAC), PEs can receive multiple MAC/IP (e.g., non-static MAC), PEs can receive multiple MAC/IP
advertisements routes for the same MAC address with different advertisements routes for the same MAC address with different
Leaf/Root indications (and possibly different ESIs for multi-homing Leaf/Root indications (and possibly different ESIs for multi-homing
scenarios). In such situations, MAC mobility procedures (section 15 scenarios). In such situations, MAC mobility procedures (section 15
of [RFC7432]) take precedence to first identify the location of the of [RFC7432]) take precedence to first identify the location of the
MAC before associating that MAC with a Root or a Leaf site. MAC before associating that MAC with a Root or a Leaf site.
To support the above ingress filtering functionality, a new E-Tree To support the above ingress filtering functionality, a new E-Tree
Extended Community with a Leaf indication flag is introduced [section Extended Community with a Leaf indication flag is introduced [section
5.1]. This new Extended Community MUST be advertised with MAC/IP 5.1]. This new Extended Community MUST be advertised with MAC/IP
Advertisement route learned from a Leaf site. Besides MAC/IP Advertisement routes learned from a Leaf site. Besides MAC/IP
Advertisement route, no other EVPN routes are required to carry this Advertisement route, no other EVPN routes are required to carry this
new extended community. new extended community.
3.2 Broadcast, Unkonwn, and Multicast (BUM) Traffic 3.2 Broadcast, Unkonwn, and Multicast (BUM) Traffic
In this specification, the support for filtering BUM (Broadcast, This specification does not provide support for filtering BUM
Unknown, and Multicast) traffic does not include ingress filtering (Broadcast, Unknown, and Multicast) traffic on the ingress PE; due to
because it is not possible to do so, due to the multi-destination the multi-destination nature of BUM traffic, is is not possible to
nature of BUM traffic. As such, the solution relies on egress perform filtering of the same on the ingress PE. As such, the
filtering. In order to apply the proper egress filtering, which solution relies on egress filtering. In order to apply the proper
varies based on whether a packet is sent from a Leaf AC or a root AC, egress filtering, which varies based on whether a packet is sent from
the MPLS-encapsulated frames MUST be tagged with an indication when a Leaf AC or a Root AC, the MPLS-encapsulated frames MUST be tagged
they originated from a Leaf AC - i.e., to be tagged with a Leaf label with an indication when they originated from a Leaf AC - i.e., to be
as specified in section 5.1. This Leaf label allows for disposition tagged with a Leaf label as specified in section 5.1. This Leaf label
PE (e.g., egress PE) to perform the necessary egress filtering allows for disposition PE (e.g., egress PE) to perform the necessary
function in data-plane similar to ESI label in [RFC7432]. The egress filtering function in data-plane similar to ESI label in
allocation of the Leaf label is on a per PE basis (e.g., independent [RFC7432]. The allocation of the Leaf label is on a per PE basis
of ESI and EVI) as descried in the following sections. (e.g., independent of ESI and EVI) as descried in the following
sections.
The Leaf label can be upstream assigned for P2MP LSP or downstream The Leaf label can be upstream assigned for P2MP LSP or downstream
assigned for ingress replication tunnels. The main difference between assigned for ingress replication tunnels. The main difference between
downstream and upstream assigned Leaf label is that in case of downstream and upstream assigned Leaf label is that in case of
downstream assigned not all egress PE devices need to receive the downstream assigned not all egress PE devices need to receive the
label in MPLS encapsulated BUM packets just like ESI label for label in MPLS encapsulated BUM packets just like ESI label for
ingress replication procedures defined in [RFC7432]. ingress replication procedures defined in [RFC7432].
On the ingress PE, the PE needs to place all its Leaf ACs for a given On the ingress PE, the PE needs to place all its Leaf ACs for a given
bridge domain in a single split-horizon group in order to prevent bridge domain in a single split-horizon group in order to prevent
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filtering applies to BUM traffic as well as known-unicast traffic. filtering applies to BUM traffic as well as known-unicast traffic.
There are four scenarios to consider as follows. In all these There are four scenarios to consider as follows. In all these
scenarios, the ingress PE imposes the right MPLS label associated scenarios, the ingress PE imposes the right MPLS label associated
with the originated Ethernet Segment (ES) depending on whether the with the originated Ethernet Segment (ES) depending on whether the
Ethernet frame originated from a Root or a Leaf site on that Ethernet Ethernet frame originated from a Root or a Leaf site on that Ethernet
Segment (ESI label or Leaf label). The mechanism by which the PE Segment (ESI label or Leaf label). The mechanism by which the PE
identifies whether a given frame originated from a Root or a Leaf identifies whether a given frame originated from a Root or a Leaf
site on the segment is based on the AC identifier for that segment site on the segment is based on the AC identifier for that segment
(e.g., Ethernet Tag of the frame for 802.1Q frames). Other mechanisms (e.g., Ethernet Tag of the frame for 802.1Q frames). Other mechanisms
for identifying root or Leaf sites such the use of source MAC address for identifying Root or Leaf sites such as the use of source MAC
of the receiving frame are optional. The scenarios below are address of the receiving frame are optional. The scenarios below are
described in context of Root/Leaf AC; however, they can be extended described in context of Root/Leaf AC; however, they can be extended
to Root/Leaf MAC address if needed. to Root/Leaf MAC address if needed.
3.2.1 BUM Traffic Originated from a Single-homed Site on a Leaf AC 3.2.1 BUM Traffic Originated from a Single-homed Site on a Leaf AC
In this scenario, the ingress PE adds a Leaf label advertised using In this scenario, the ingress PE adds a Leaf label advertised using
the E-Tree Extended Community (Section 5.1) indicating a Leaf site. the E-Tree Extended Community (Section 5.1) indicating a Leaf site.
This Leaf label, used for single-homing scenarios, is not on a per ES This Leaf label, used for single-homing scenarios, is not on a per ES
basis but rather on a per PE basis - i.e., a single Leaf MPLS label basis but rather on a per PE basis - i.e., a single Leaf MPLS label
is used for all single-homed ES's on that PE. This Leaf label is is used for all single-homed ES's on that PE. This Leaf label is
advertised to other PE devices, using the E-Tree Extended Community advertised to other PE devices, using the E-Tree Extended Community
(section 5.1) along with an Ethernet A-D per ES route with ESI of (section 5.1) along with an Ethernet Auto-discovery per ES (EAD-ES)
zero and a set of Route Targets (RTs) corresponding to all EVIs on route with ESI of zero and a set of Route Targets (RTs) corresponding
the PE where each EVI has at least one Leaf site. Multiple Ethernet to all EVIs on the PE where each EVI has at least one Leaf site.
A-D per ES routes will need to be advertised if the number of Route Multiple EAD-ES routes will need to be advertised if the number of
Targets (RTs) that need to be carried exceed the limit on a single Route Targets (RTs) that need to be carried exceed the limit on a
route per [RFC7432]. The ESI for the Ethernet A-D per ES route is set single route per [RFC7432]. The ESI for the EAD-ES route is set to
to zero to indicate single-homed sites. zero to indicate single-homed sites.
When a PE receives this special Leaf label in the data path, it When a PE receives this special Leaf label in the data path, it
blocks the packet if the destination AC is of type Leaf; otherwise, blocks the packet if the destination AC is of type Leaf; otherwise,
it forwards the packet. it forwards the packet.
3.2.2 BUM Traffic Originated from a Single-homed Site on a Root AC 3.2.2 BUM Traffic Originated from a Single-homed Site on a Root AC
In this scenario, the ingress PE does not add any ESI label or Leaf In this scenario, the ingress PE does not add any ESI label or Leaf
label and it operates per [RFC7432] procedures. label and it operates per [RFC7432] procedures.
3.2.3 BUM Traffic Originated from a Multi-homed Site on a Leaf AC 3.2.3 BUM Traffic Originated from a Multi-homed Site on a Leaf AC
In this scenario, it is assumed that while different ACs (VLANs) on In this scenario, it is assumed that while different ACs (VLANs) on
the same ES could have different Root/Leaf designation (some being the same ES could have different Root/Leaf designation (some being
roots and some being leafs), the same VLAN does have the same Roots and some being Leafs), the same VLAN does have the same
Root/Leaf designation on all PEs on the same ES. Furthermore, it is Root/Leaf designation on all PEs on the same ES. Furthermore, it is
assumed that there is no forwarding among subnets - ie, the service assumed that there is no forwarding among subnets - ie, the service
is EVPN L2 and not EVPN IRB [EVPN-IRB]. IRB use cases described in is EVPN L2 and not EVPN IRB [EVPN-IRB]. IRB use cases described in
[EVPN-IRB] are outside the scope of this document. [EVPN-IRB] are outside the scope of this document.
In this scenario, If a multicast or broadcast packet is originated In this scenario, if a multicast or broadcast packet is originated
from a Leaf AC, then it only needs to carry Leaf label described in from a Leaf AC, then it only needs to carry Leaf label described in
section 3.2.1. This label is sufficient in providing the necessary section 3.2.1. This label is sufficient in providing the necessary
egress filtering of BUM traffic from getting sent to Leaf ACs egress filtering of BUM traffic from getting sent to Leaf ACs
including the Leaf AC on the same Ethernet Segment. including the Leaf AC on the same Ethernet Segment.
3.2.4 BUM Traffic Originated from a Multi-homed Site on a Root AC 3.2.4 BUM Traffic Originated from a Multi-homed Site on a Root AC
In this scenario, both the ingress and egress PE devices follows the In this scenario, both the ingress and egress PE devices follows the
procedure defined in [RFC7432] for adding and/or processing an ESI procedure defined in [RFC7432] for adding and/or processing an ESI
MPLS label - i.e., existing procedures for BUM traffic in [RFC7432] MPLS label - i.e., existing procedures for BUM traffic in [RFC7432]
skipping to change at page 12, line 39 skipping to change at page 12, line 39
data-path over the Ethernet Segments, and advertises reachability in data-path over the Ethernet Segments, and advertises reachability in
EVPN MAC/IP Advertisement Routes. These routes will be imported by EVPN MAC/IP Advertisement Routes. These routes will be imported by
all PEs for that EVI (i.e., PEs that have Leaf sites as well as PEs all PEs for that EVI (i.e., PEs that have Leaf sites as well as PEs
that have Root sites). Similarly, the PEs with Leaf sites perform MAC that have Root sites). Similarly, the PEs with Leaf sites perform MAC
learning in the data-path over their Ethernet Segments, and advertise learning in the data-path over their Ethernet Segments, and advertise
reachability in EVPN MAC/IP Advertisement Routes. For scenarios where reachability in EVPN MAC/IP Advertisement Routes. For scenarios where
two different RTs are used per EVI (one to designate Root site and two different RTs are used per EVI (one to designate Root site and
another to designate Leaf site), the MAC/IP Advertisement routes are another to designate Leaf site), the MAC/IP Advertisement routes are
imported only by PEs with at least one Root site in the EVI - i.e., a imported only by PEs with at least one Root site in the EVI - i.e., a
PE with only Leaf sites will not import these routes. PEs with Root PE with only Leaf sites will not import these routes. PEs with Root
and/or Leaf sites may use the Ethernet A-D routes for aliasing (in and/or Leaf sites may use the Ethernet Auto-discovery per EVI (EAD-
the case of multi-homed segments) and for mass MAC withdrawal per EVI) routes for aliasing (in the case of multi-homed segments) and
[RFC7432]. EAD-ES routes for mass MAC withdrawal per [RFC7432].
To support multicast/broadcast from Root to Leaf sites, either a P2MP To support multicast/broadcast from Root to Leaf sites, either a P2MP
tree rooted at the PE(s) with the Root site(s) (e.g., Root PEs) or tree rooted at the PE(s) with the Root site(s) (e.g., Root PEs) or
ingress replication can be used (section 16 of [RFC7432]). The ingress replication can be used (section 16 of [RFC7432]). The
multicast tunnels are set up through the exchange of the EVPN multicast tunnels are set up through the exchange of the EVPN
Inclusive Multicast route, as defined in [RFC7432]. Inclusive Multicast route, as defined in [RFC7432].
To support multicast/broadcast from Leaf to Root sites, either To support multicast/broadcast from Leaf to Root sites, either
ingress replication tunnels from each Leaf PE or a P2MP tree rooted ingress replication tunnels from each Leaf PE or a P2MP tree rooted
at each Leaf PE can be used. The following two paragraphs describes at each Leaf PE can be used. The following two paragraphs describes
when each of these tunneling schemes can be used and how to signal when each of these tunneling schemes can be used and how to signal
them. them.
When there are only a few Root PEs with small amount of When there are only a few Root PEs with small amount of
multicast/broadcast traffic from Leaf PEs toward Root PEs, then multicast/broadcast traffic from Leaf PEs toward Root PEs, then
ingress replication tunnels from Leaf PEs toward Root PEs should be ingress replication tunnels from Leaf PEs toward Root PEs should be
sufficient. Therefore, if a root PE needs to support a P2MP tunnel in sufficient. Therefore, if a Root PE needs to support a P2MP tunnel in
transmit direction from itself to Leaf PEs and at the same time it transmit direction from itself to Leaf PEs and at the same time it
wants to support ingress-replication tunnels in receive direction, wants to support ingress-replication tunnels in receive direction,
the Root PE can signal it efficiently by using a new composite tunnel the Root PE can signal it efficiently by using a new composite tunnel
type defined in section 5.2. This new composite tunnel type is type defined in section 5.2. This new composite tunnel type is
advertised by the root PE to simultaneously indicate a P2MP tunnel in advertised by the Root PE to simultaneously indicate a P2MP tunnel in
transmit direction and an ingress-replication tunnel in the receive transmit direction and an ingress-replication tunnel in the receive
direction for the BUM traffic. direction for the BUM traffic.
If the number of Root PEs is large, P2MP tunnels (e.g., mLDP or RSVP- If the number of Root PEs is large, P2MP tunnels (e.g., mLDP or RSVP-
TE) originated at the Leaf PEs may be used and thus there will be no TE) originated at the Leaf PEs may be used and thus there will be no
need to use the modified PMSI tunnel attribute and the composite need to use the modified PMSI tunnel attribute and the composite
tunnel type values defined in section 5.2. tunnel type values defined in section 5.2.
3.3.2 E-Tree without MAC Learning 3.3.2 E-Tree without MAC Learning
The PEs implementing an E-Tree service need not perform MAC learning The PEs implementing an E-Tree service need not perform MAC learning
when the traffic flows between Root and Leaf sites are mainly when the traffic flows between Root and Leaf sites are mainly
multicast or broadcast. In this case, the PEs do not exchange EVPN multicast or broadcast. In this case, the PEs do not exchange EVPN
MAC/IP Advertisement Routes. Instead, the Inclusive Multicast MAC/IP Advertisement Routes. Instead, the Inclusive Multicast
Ethernet Tag route is used to support BUM traffic. Ethernet Tag route is used to support BUM traffic. In such scenarios,
the small amount of unicast traffic (if any) is sent as part of BUM
traffic.
The fields of this route are populated per the procedures defined in The fields of this route are populated per the procedures defined in
[RFC7432], and the multicast tunnel setup criteria are as described [RFC7432], and the multicast tunnel setup criteria are as described
in the previous section. in the previous section.
Just as in the previous section, if the number of Root PEs are only a Just as in the previous section, if the number of Root PEs are only a
few and thus ingress replication is desired from Leaf PEs to these few and thus ingress replication is desired from Leaf PEs to these
root PEs, then the modified PMSI attribute and the composite tunnel Root PEs, then the modified PMSI attribute and the composite tunnel
type values defined in section 5.2 should be used. type values defined in section 5.2 should be used.
4 Operation for PBB-EVPN 4 Operation for PBB-EVPN
In PBB-EVPN, the PE advertises a Root/Leaf indication along with each In PBB-EVPN, the PE advertises a Root/Leaf indication along with each
B-MAC Advertisement route, to indicate whether the associated B-MAC B-MAC Advertisement route to indicate whether the associated B-MAC
address corresponds to a Root or a Leaf site. Just like the EVPN address corresponds to a Root or a Leaf site. Just like the EVPN
case, the new E-Tree Extended Community defined in section [5.1] is case, the new E-Tree Extended Community defined in section [5.1] is
advertised with each EVPN MAC/IP Advertisement route. advertised with each EVPN MAC/IP Advertisement route.
In the case where a multi-homed Ethernet Segment has both Root and In the case where a multi-homed Ethernet Segment has both Root and
Leaf sites attached, two B-MAC addresses are advertised: one B-MAC Leaf sites attached, two B-MAC addresses are advertised: one B-MAC
address is per ES as specified in [RFC7623] and implicitly denoting address is per ES as specified in [RFC7623] and implicitly denoting
Root, and the other B-MAC address is per PE and explicitly denoting Root, and the other B-MAC address is per PE and explicitly denoting
Leaf. The former B-MAC address is not advertised with the E-Tree Leaf. The former B-MAC address is not advertised with the E-Tree
extended community but the latter B-MAC denoting Leaf is advertised extended community but the latter B-MAC denoting Leaf is advertised
with the new E-Tree extended community where "Leaf-indication" flag with the new E-Tree extended community where "Leaf-indication" flag
is set. In such multi-homing scenarios where an Ethernet Segment has is set. In multi-homing scenarios where an Ethernet Segment has both
both Root and Leaf ACs, it is assumed that While different ACs Root and Leaf ACs, it is assumed that while different ACs (VLANs) on
(VLANs) on the same ES could have different Root/Leaf designation the same ES could have different Root/Leaf designation (some being
(some being Roots and some being Leafs), the same VLAN does have the Roots and some being Leafs), the same VLAN does have the same
same Root/Leaf designation on all PEs on the same ES. Furthermore, it Root/Leaf designation on all PEs on the same ES. Furthermore, it is
is assumed that there is no forwarding among subnets - ie, the assumed that there is no forwarding among subnets - ie, the service
service is L2 and not IRB. IRB use case is outside the scope of this is L2 and not IRB. IRB use case is outside the scope of this
document. document.
The ingress PE uses the right B-MAC source address depending on The ingress PE uses the right B-MAC source address depending on
whether the Ethernet frame originated from the Root or Leaf AC on whether the Ethernet frame originated from the Root or Leaf AC on
that Ethernet Segment. The mechanism by which the PE identifies that Ethernet Segment. The mechanism by which the PE identifies
whether a given frame originated from a Root or Leaf site on the whether a given frame originated from a Root or Leaf site on the
segment is based on the Ethernet Tag associated with the frame. Other segment is based on the Ethernet Tag associated with the frame. Other
mechanisms of identification, beyond the Ethernet Tag, are outside mechanisms of identification, beyond the Ethernet Tag, are outside
the scope of this document. the scope of this document.
Furthermore, a PE advertises two special global B-MAC addresses: one Furthermore, a PE advertises two special global B-MAC addresses: one
for Root and another for Leaf, and tags the Leaf one as such in the for Root and another for Leaf, and tags the Leaf one as such in the
MAC Advertisement route. These B-MAC addresses are used as source MAC Advertisement route. These B-MAC addresses are used as source
addresses for traffic originating from single-homed segments. The B- addresses for traffic originating from single-homed segments. The B-
MAC address used for indicating Leaf sites can be the same for both MAC address used for indicating Leaf sites can be the same for both
single-homed and multi-homed segments. single-homed and multi-homed segments.
4.1 Known Unicast Traffic 4.1 Known Unicast Traffic
For known unicast traffic, the PEs perform ingress filtering: On the For known unicast traffic, the PEs perform ingress filtering: On the
ingress PE, the C-MAC destination address lookup yields, in addition ingress PE, the C-MAC [RFC7623] destination address lookup yields, in
to the target B-MAC address and forwarding adjacency, a flag which addition to the target B-MAC address and forwarding adjacency, a flag
indicates whether the target B-MAC is associated with a Root or a which indicates whether the target B-MAC is associated with a Root or
Leaf site. The ingress PE also checks the status of the originating a Leaf site. The ingress PE also checks the status of the originating
site, and if both are a Leaf, then the packet is not forwarded. site, and if both are a Leaf, then the packet is not forwarded.
4.2 Broadcast, Unkonwn, and Multicast (BUM) Traffic 4.2 Broadcast, Unkonwn, and Multicast (BUM) Traffic
For BUM traffic, the PEs must perform egress filtering. When a PE For BUM traffic, the PEs must perform egress filtering. When a PE
receives an EVPN MAC/IP advertisement route (which will be used as a receives an EVPN MAC/IP advertisement route (which will be used as a
source B-MAC for BUM traffic), it updates its egress filtering (based source B-MAC for BUM traffic), it updates its egress filtering (based
on the source B-MAC address), as follows: on the source B-MAC address), as follows:
- If the EVPN MAC/IP Advertisement route indicates that the - If the EVPN MAC/IP Advertisement route indicates that the
skipping to change at page 15, line 30 skipping to change at page 15, line 32
that this uses the same filtering logic as baseline [RFC7623] for an that this uses the same filtering logic as baseline [RFC7623] for an
ESI and does not require any additional flags in the data-plane. ESI and does not require any additional flags in the data-plane.
Just as in section 3.2, the PE places all Leaf Ethernet Segments of a Just as in section 3.2, the PE places all Leaf Ethernet Segments of a
given bridge domain in a single split-horizon group in order to given bridge domain in a single split-horizon group in order to
prevent intra-PE forwarding among Leaf segments. This split-horizon prevent intra-PE forwarding among Leaf segments. This split-horizon
function applies to BUM traffic as well as known-unicast traffic. function applies to BUM traffic as well as known-unicast traffic.
4.3 E-Tree without MAC Learning 4.3 E-Tree without MAC Learning
In scenarios where the traffic of interest is only Multicast and/or In scenarios where the traffic of interest is only multicast and/or
broadcast, the PEs implementing an E-Tree service do not need to do broadcast, the PEs implementing an E-Tree service do not need to do
any MAC learning. In such scenarios the filtering must be performed any MAC learning. In such scenarios the filtering must be performed
on egress PEs. For PBB-EVPN, the handling of such traffic is per on egress PEs. For PBB-EVPN, the handling of such traffic is per
section 4.2 without the need for C-MAC learning (in data-plane) in I- section 4.2 without the need for C-MAC learning (in data-plane) in I-
component (C-bridge table) of PBB-EVPN PEs (at both ingress and component (C-bridge table) of PBB-EVPN PEs (at both ingress and
egress PEs). egress PEs).
5 BGP Encoding 5 BGP Encoding
This document defines a new BGP Extended Community for EVPN. This document defines a new BGP Extended Community for EVPN.
skipping to change at page 16, line 33 skipping to change at page 16, line 35
This document defines the following flags: This document defines the following flags:
+ Leaf-Indication (L) + Leaf-Indication (L)
A value of one indicates a Leaf AC/Site. The rest of flag bits are A value of one indicates a Leaf AC/Site. The rest of flag bits are
reserved and should be set to zero. reserved and should be set to zero.
When this Extended Community (EC) is advertised along with MAC/IP When this Extended Community (EC) is advertised along with MAC/IP
Advertisement route (for known unicast traffic) per section 3.1, the Advertisement route (for known unicast traffic) per section 3.1, the
Leaf-Indication flag MUST be set to one and Leaf Label SHOULD be set Leaf-Indication flag MUST be set to one and Leaf Label SHOULD be set
to zero. The value of the 20-bit MPLS label is encoded in the high- to zero. The receiving PE MUST ignore Leaf Label and only processes
order 20 bits of the Leaf Label field. The receiving PE SHOULD ignore Leaf-Indication flag. A value of zero for Leaf-Indication flag is
Leaf Label and only processes Leaf-Indication flag. A value of zero invalid when sent along with MAC/IP advertisement route and an error
for Leaf-Indication flag is invalid when sent along with MAC/IP should be logged.
advertisement route and an error should be logged.
When this EC is advertised along with Ethernet A-D per ES route (with When this EC is advertised along with EAD-ES route (with ESI of zero)
ESI of zero) for BUM traffic to enable egress filtering on for BUM traffic to enable egress filtering on disposition PEs per
disposition PEs per sections 3.2.1 and 3.2.3, the Leaf Label MUST be sections 3.2.1 and 3.2.3, the Leaf Label MUST be set to a valid MPLS
set to a valid MPLS label (i.e., non-reserved assigned MPLS label label (i.e., non-reserved assigned MPLS label [RFC3032]) and the
[RFC3032]) and the Leaf-Indication flag SHOULD be set to zero. The Leaf-Indication flag SHOULD be set to zero. The value of the 20-bit
receiving PE SHOULD ignore the Leaf-Indication flag. A non-valid MPLS MPLS label is encoded in the high-order 20 bits of the Leaf Label
label when sent along with the Ethernet A-D per ES route, should be field. The receiving PE MUST ignore the Leaf-Indication flag. A non-
valid MPLS label when sent along with the EAD-ES route, should be
ignored and logged as an error. ignored and logged as an error.
The reserved bits SHOULD be set to zero by the transmitter and SHOULD The reserved bits SHOULD be set to zero by the transmitter and MUST
be ignored by the receiver. be ignored by the receiver.
5.2 PMSI Tunnel Attribute 5.2 PMSI Tunnel Attribute
[RFC6514] defines PMSI Tunnel attribute which is an optional [RFC6514] defines PMSI Tunnel attribute which is an optional
transitive attribute with the following format: transitive attribute with the following format:
+---------------------------------+ +---------------------------------+
| Flags (1 octet) | | Flags (1 octet) |
+---------------------------------+ +---------------------------------+
skipping to change at page 17, line 26 skipping to change at page 17, line 27
| (3 octets) | | (3 octets) |
+---------------------------------+ +---------------------------------+
| Tunnel Identifier (variable) | | Tunnel Identifier (variable) |
+---------------------------------+ +---------------------------------+
Figure 5: PMSI Tunnel Attribute Figure 5: PMSI Tunnel Attribute
This document defines a new Composite tunnel type by introducing a This document defines a new Composite tunnel type by introducing a
new 'Composite Tunnel' bit in the Tunnel Type field and adding a MPLS new 'Composite Tunnel' bit in the Tunnel Type field and adding a MPLS
label to the Tunnel Identifier field of PMSI Tunnel attribute as label to the Tunnel Identifier field of PMSI Tunnel attribute as
detailed below. This document uses all other remaining fields per detailed below. All other fields remain as defined in [RFC6514].
existing definition. Composite tunnel type is advertised by the root Composite tunnel type is advertised by the Root PE to simultaneously
PE to simultaneously indicate a non-(ingress replication) tunnel indicate a non-(ingress replication) tunnel (e.g., P2MP tunnel) in
(e.g., P2MP tunnel) in transmit direction and an ingress-replication transmit direction and an ingress-replication tunnel in the receive
tunnel in the receive direction for the BUM traffic. direction for the BUM traffic.
When receiver ingress-replication label is needed, the high-order bit When receiver ingress-replication labels are needed, the high-order
of the tunnel type field (Composite Tunnel bit) is set while the bit of the tunnel type field (Composite Tunnel bit) is set while the
remaining low-order seven bits indicate the tunnel type as before remaining low-order seven bits indicate the tunnel type as before
(for the existing tunnel types). When this Composite Tunnel bit is (for the existing tunnel types). When this Composite Tunnel bit is
set, the "tunnel identifier" field begins with a three-octet label, set, the "tunnel identifier" field begins with a three-octet label,
followed by the actual tunnel identifier for the transmit tunnel. followed by the actual tunnel identifier for the transmit tunnel.
PEs that don't understand the new meaning of the high-order bit would PEs that don't understand the new meaning of the high-order bit treat
treat the tunnel type as an undefined tunnel type and would treat the the tunnel type as an undefined tunnel type and treat the PMSI tunnel
PMSI tunnel attribute as a malformed attribute [RFC6514]. That is why attribute as a malformed attribute [RFC6514]. That is why the
the composite tunnel bit is allocated in the Tunnel Type field rather composite tunnel bit is allocated in the Tunnel Type field rather
than the Flags field. For the PEs that do understand the new meaning than the Flags field. For the PEs that do understand the new meaning
of the high-order, if ingress replication is desired when sending BUM of the high-order, if ingress replication is desired when sending BUM
traffic, the PE will use the the label in the Tunnel Identifier field traffic, the PE will use the the label in the Tunnel Identifier field
when sending its BUM traffic. when sending its BUM traffic.
Using the Composite Tunnel bit for Tunnel Types 0x00 'no tunnel Using the Composite Tunnel bit for Tunnel Types 0x00 'no tunnel
information present' and 0x06 'Ingress Replication' is invalid, and a information present' and 0x06 'Ingress Replication' is invalid, and a
PE that receives a PMSI Tunnel attribute with such information, PE that receives a PMSI Tunnel attribute with such information,
considers it as malformed and it SHOULD treat this Update as though considers it as malformed and it SHOULD treat this Update as though
all the routes contained in this Update had been withdrawn per all the routes contained in this Update had been withdrawn per
section 5 of [RFC6514]. section 5 of [RFC6514].
6 Acknowledgement 6 Acknowledgement
We would like to thank Eric Rosen, Jeffrey Zhang, Dennis Cai, and We would like to thank Eric Rosen, Jeffrey Zhang, Wen Lin, Aldrin
Antoni Przygienda for their valuable comments. The authors would also Issac, Wim Henderickx, Dennis Cai, and Antoni Przygienda for their
like to thank Thomas Morin for shepherding this document and valuable comments and contributions. The authors would also like to
providing valuable comments. thank Thomas Morin for shepherding this document and providing
valuable comments.
7 Security Considerations 7 Security Considerations
Since this document uses the EVPN constructs of [RFC7432] and Since this document uses the EVPN constructs of [RFC7432] and
[RFC7623], the same security considerations in these documents are [RFC7623], the same security considerations in these documents are
also applicable here. Furthermore, this document provides additional also applicable here. Furthermore, this document provides an
security check by allowing sites (or ACs) of an EVPN instance to be additional security check by allowing sites (or ACs) of an EVPN
designated as "Root" or "Leaf" and preventing any traffic exchange instance to be designated as "Root" or "Leaf" by the network
operator/ service provider and thus preventing any traffic exchange
among "Leaf" sites of that VPN through ingress filtering for known among "Leaf" sites of that VPN through ingress filtering for known
unicast traffic and egress filtering for BUM traffic. unicast traffic and egress filtering for BUM traffic. Since by
default and for the purpose of backward compatibility, an AC that
doesn't have a Leaf designation is considered as a Root AC, in order
to avoid any traffic exchange among Leaf ACs, the operator SHOULD
configure the AC with a proper role (Leaf or Root) before activating
the AC.
8 IANA Considerations 8 IANA Considerations
IANA has allocated value 5 in the "EVPN Extended Community Sub-Types" IANA has allocated value 5 in the "EVPN Extended Community Sub-Types"
registry defined in [RFC7153] as follow: registry defined in [RFC7153] as follow:
SUB-TYPE VALUE NAME Reference SUB-TYPE VALUE NAME Reference
0x05 E-Tree Extended Community This document 0x05 E-Tree Extended Community This document
skipping to change at page 19, line 6 skipping to change at page 19, line 17
0-6 Unassigned 0-6 Unassigned
7 Leaf-Indication This document 7 Leaf-Indication This document
8.1 Considerations for PMSI Tunnel Types 8.1 Considerations for PMSI Tunnel Types
The "P-Multicast Service Interface Tunnel (PMSI Tunnel) Tunnel Types" The "P-Multicast Service Interface Tunnel (PMSI Tunnel) Tunnel Types"
registry in the "Border Gateway Protocol (BGP) Parameters" registry registry in the "Border Gateway Protocol (BGP) Parameters" registry
needs to be updated to reflect the use of the most significant bit as needs to be updated to reflect the use of the most significant bit as
"Composite Tunnel" bit (section 5.2). "Composite Tunnel" bit (section 5.2).
For this purpose, this document updates [RFC7385]. For this purpose, this document updates [RFC7385] by changing the
previously unassigned values (i.e., 0x08 - 0xFA) as follow:
The registry is to be updated, by removing the entries for 0xFB-0xFE
and 0x0F, and replacing them by:
Value Meaning Reference Value Meaning Reference
0x0C-0x7A Unassigned 0x08-0x7A Unassigned
0x7B-0x7E Experimental this document 0x7B-0x7E Experimental this document
0x7F Reserved this document 0x7F Reserved this document
0x80-0xFA Reserved for Composite tunnel this document 0x80-0xFA Reserved for Composite tunnel this document
0xFB-0xFE Experimental [RFC7385] 0xFB-0xFE Experimental [RFC7385]
0xFF Reserved [RFC7385] 0xFF Reserved [RFC7385]
The allocation policy for values 0x00 to 0x7A is IETF Review The allocation policy for values 0x08-0x7A is per IETF Review
[RFC8126]. The range for experimental use is now 0x7B-0x7E, and value [RFC8126]. The range for experimental has been expanded to include
in this range are not to be assigned. The status of 0x7F may only be the previously assigned range of 0xFB-0xFE and the new range of 0x7B-
changed through Standards Action [RFC8126]. 0x7E. The value in these ranges are not to be assigned. The value
0x7F which is the mirror image of (0xFF) is reserved in this
document.
9 References 9 References
9.1 Normative References 9.1 Normative References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC8126] Cotton et al, "Guidelines for Writing an IANA [RFC8126] Cotton et al, "Guidelines for Writing an IANA
Considerations Section in RFCs", June, 2017. Considerations Section in RFCs", June, 2017.
skipping to change at page 20, line 36 skipping to change at page 20, line 47
2017. 2017.
[802.1ah] IEEE, "IEEE Standard for Local and metropolitan area [802.1ah] IEEE, "IEEE Standard for Local and metropolitan area
networks - Media Access Control (MAC) Bridges and Virtual Bridged networks - Media Access Control (MAC) Bridges and Virtual Bridged
Local Area Networks", Clauses 25 and 26, IEEE Std 802.1Q, DOI Local Area Networks", Clauses 25 and 26, IEEE Std 802.1Q, DOI
10.1109/IEEESTD.2011.6009146. 10.1109/IEEESTD.2011.6009146.
Appendix-A Appendix-A
When two MAC-VRFs (two bridge tables per VLANs) are used for an E- When two MAC-VRFs (two bridge tables per VLANs) are used for an E-
Tree service (one for root ACs and another for Leaf ACs) on a given Tree service (one for Root ACs and another for Leaf ACs) on a given
PE, then the following complications in data-plane path can result. PE, then the following complications in data-plane path can result.
Maintaining two MAC-VRFs (two bridge tables) per VLAN (when both Leaf Maintaining two MAC-VRFs (two bridge tables) per VLAN (when both Leaf
and Root ACs exists for that VLAN) would either require two lookups and Root ACs exists for that VLAN) would either require two lookups
be performed per MAC address in each direction in case of a miss, or be performed per MAC address in each direction in case of a miss, or
duplicating many MAC addresses between the two bridge tables duplicating many MAC addresses between the two bridge tables
belonging to the same VLAN (same E-Tree instance). Unless two lookups belonging to the same VLAN (same E-Tree instance). Unless two lookups
are made, duplication of MAC addresses would be needed for both are made, duplication of MAC addresses would be needed for both
locally learned and remotely learned MAC addresses. Locally learned locally learned and remotely learned MAC addresses. Locally learned
MAC addresses from Leaf ACs need to be duplicated onto Root bridge MAC addresses from Leaf ACs need to be duplicated onto Root bridge
table and locally learned MAC addresses from Root ACs need to be table and locally learned MAC addresses from Root ACs need to be
duplicated onto Leaf bridge table. Remotely learned MAC addresses duplicated onto Leaf bridge table. Remotely learned MAC addresses
from Root ACs need to be copied onto both Root and Leaf bridge from Root ACs need to be copied onto both Root and Leaf bridge
tables. Because of potential inefficiencies associated with data- tables. Because of potential inefficiencies associated with data-
plane implementation of additional MAC lookup or duplication of MAC plane implementation of additional MAC lookup or duplication of MAC
entries, this option is not believed to be implementable without entries, this option is not believed to be implementable without
dataplane performance inefficiencies in some platforms and thus this dataplane performance inefficiencies in some platforms and thus this
document introduces the coloring as described in section 2.2 and document introduces the coloring as described in section 2.2 and
detailed in section 3.1. detailed in section 3.1.
Contributors
In addition to the authors listed on the front page, the following
co-authors have also contributed to this document:
Wim Henderickx
Nokia
Aldrin Isaac
Wen Lin
Juniper
Authors' Addresses Authors' Addresses
Ali Sajassi Ali Sajassi
Cisco Cisco
Email: sajassi@cisco.com Email: sajassi@cisco.com
Samer Salam Samer Salam
Cisco Cisco
Email: ssalam@cisco.com Email: ssalam@cisco.com
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