draft-ietf-bess-evpn-etree-14.txt   rfc8317.txt 
BESS Workgroup A. Sajassi, Ed. Internet Engineering Task Force (IETF) A. Sajassi, Ed.
INTERNET-DRAFT S. Salam Request for Comments: 8317 S. Salam
Intended Status: Standards Track Cisco Updates: 7385 Cisco
Updates: 7385 J. Drake Category: Standards Track J. Drake
Juniper ISSN: 2070-1721 Juniper
J. Uttaro J. Uttaro
ATT ATT
S. Boutros S. Boutros
VMware VMware
J. Rabadan J. Rabadan
Nokia Nokia
January 2018
Expires: April 28, 2018 October 28, 2017 Ethernet-Tree (E-Tree) Support in Ethernet VPN (EVPN) and
Provider Backbone Bridging EVPN (PBB-EVPN)
E-TREE Support in EVPN & PBB-EVPN
draft-ietf-bess-evpn-etree-14
Abstract Abstract
The Metro Ethernet Forum (MEF) has defined a rooted-multipoint The MEF Forum (MEF) has defined a rooted-multipoint Ethernet service
Ethernet service known as Ethernet Tree (E-Tree). A solution known as Ethernet-Tree (E-Tree). A solution framework for supporting
framework for supporting this service in MPLS networks is described this service in MPLS networks is described in RFC 7387, "A Framework
in RFC7387 ("A Framework for Ethernet-Tree (E-Tree) Service over a for Ethernet-Tree (E-Tree) Service over a Multiprotocol Label
Multiprotocol Label Switching (MPLS) Network"). This document Switching (MPLS) Network". This document discusses how those
discusses how those functional requirements can be met with a functional requirements can be met with a solution based on RFC 7432,
solution based on RFC7432, BGP MPLS Based Ethernet VPN (EVPN), with "BGP MPLS Based Ethernet VPN (EVPN)", with some extensions and a
some extensions and how such a solution can offer a more efficient description of how such a solution can offer a more efficient
implementation of these functions than that of RFC7796, E-Tree implementation of these functions than that of RFC 7796,
Support in Virtual Private LAN Service (VPLS). This document makes "Ethernet-Tree (E-Tree) Support in Virtual Private LAN Service
use of the most significant bit of the "Tunnel Type" field (in PMSI (VPLS)". This document makes use of the most significant bit of the
Tunnel Attribute) governed by the IANA registry created by RFC7385, Tunnel Type field (in the P-Multicast Service Interface (PMSI) Tunnel
and hence updates RFC7385 accordingly. attribute) governed by the IANA registry created by RFC 7385; hence,
it updates RFC 7385 accordingly.
Status of this Memo
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Copyright and License Notice Copyright Notice
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Table of Contents Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Specification of Requirements . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1. Specification of Requirements . . . . . . . . . . . . . . 5
2 E-Tree Scenarios . . . . . . . . . . . . . . . . . . . . . . . 5 2.2. Terms and Abbreviations . . . . . . . . . . . . . . . . . 5
2.1 Scenario 1: Leaf or Root Site(s) per PE . . . . . . . . . . 6 3. E-Tree Scenarios . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Scenario 2: Leaf or Root Site(s) per AC . . . . . . . . . . 6 3.1. Scenario 1: Leaf or Root Site(s) per PE . . . . . . . . . 6
2.3 Scenario 3: Leaf or Root Site(s) per MAC Address . . . . . . 8 3.2. Scenario 2: Leaf or Root Site(s) per AC . . . . . . . . . 7
3 Operation for EVPN . . . . . . . . . . . . . . . . . . . . . . . 9 3.3. Scenario 3: Leaf or Root Site(s) per MAC Address . . . . 8
3.1 Known Unicast Traffic . . . . . . . . . . . . . . . . . . . 9 4. Operation for EVPN . . . . . . . . . . . . . . . . . . . . . 9
3.2 Broadcast, Unkonwn, and Multicast (BUM) Traffic . . . . . . 10 4.1. Known Unicast Traffic . . . . . . . . . . . . . . . . . . 9
3.2.1 BUM Traffic Originated from a Single-homed Site on a 4.2. BUM Traffic . . . . . . . . . . . . . . . . . . . . . . . 10
Leaf AC . . . . . . . . . . . . . . . . . . . . . . . . 11 4.2.1. BUM Traffic Originated from a Single-Homed Site on a
3.2.2 BUM Traffic Originated from a Single-homed Site on a Leaf AC . . . . . . . . . . . . . . . . . . . . . . . 11
Root AC . . . . . . . . . . . . . . . . . . . . . . . . 11 4.2.2. BUM Traffic Originated from a Single-Homed Site on a
3.2.3 BUM Traffic Originated from a Multi-homed Site on a Root AC . . . . . . . . . . . . . . . . . . . . . . . 11
Leaf AC . . . . . . . . . . . . . . . . . . . . . . . . 11 4.2.3. BUM Traffic Originated from a Multihomed Site on a
3.2.4 BUM Traffic Originated from a Multi-homed Site on a Leaf AC . . . . . . . . . . . . . . . . . . . . . . . 12
Root AC . . . . . . . . . . . . . . . . . . . . . . . . 11 4.2.4. BUM Traffic Originated from a Multihomed Site on a
3.3 E-Tree Traffic Flows for EVPN . . . . . . . . . . . . . . . 12 Root AC . . . . . . . . . . . . . . . . . . . . . . . 12
3.3.1 E-Tree with MAC Learning . . . . . . . . . . . . . . . . 12 4.3. E-Tree Traffic Flows for EVPN . . . . . . . . . . . . . . 12
3.3.2 E-Tree without MAC Learning . . . . . . . . . . . . . . 13 4.3.1. E-Tree with MAC Learning . . . . . . . . . . . . . . 13
4 Operation for PBB-EVPN . . . . . . . . . . . . . . . . . . . . . 13 4.3.2. E-Tree without MAC Learning . . . . . . . . . . . . . 14
4.1 Known Unicast Traffic . . . . . . . . . . . . . . . . . . . 14 5. Operation for PBB-EVPN . . . . . . . . . . . . . . . . . . . 14
4.2 Broadcast, Unkonwn, and Multicast (BUM) Traffic . . . . . . 14 5.1. Known Unicast Traffic . . . . . . . . . . . . . . . . . . 15
4.3 E-Tree without MAC Learning . . . . . . . . . . . . . . . . 15 5.2. BUM Traffic . . . . . . . . . . . . . . . . . . . . . . . 15
5 BGP Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . 15 5.3. E-Tree without MAC Learning . . . . . . . . . . . . . . . 16
5.1 E-Tree Extended Community . . . . . . . . . . . . . . . . . 15 6. BGP Encoding . . . . . . . . . . . . . . . . . . . . . . . . 16
5.2 PMSI Tunnel Attribute . . . . . . . . . . . . . . . . . . . 17 6.1. E-Tree Extended Community . . . . . . . . . . . . . . . . 16
6 Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . 18 6.2. PMSI Tunnel Attribute . . . . . . . . . . . . . . . . . . 17
7 Security Considerations . . . . . . . . . . . . . . . . . . . . 18 7. Security Considerations . . . . . . . . . . . . . . . . . . . 18
8 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 18 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
8.1 Considerations for PMSI Tunnel Types . . . . . . . . . . . . 19 8.1. Considerations for PMSI Tunnel Types . . . . . . . . . . 19
9 References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
9.1 Normative References . . . . . . . . . . . . . . . . . . . 19 9.1. Normative References . . . . . . . . . . . . . . . . . . 20
9.2 Informative References . . . . . . . . . . . . . . . . . . 20 9.2. Informative References . . . . . . . . . . . . . . . . . 21
Appendix-A . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Appendix A. Multiple Bridge Tables per E-Tree Service Instance . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1 Introduction 1. Introduction
The Metro Ethernet Forum (MEF) has defined a rooted-multipoint The MEF Forum (MEF) has defined a rooted-multipoint Ethernet service
Ethernet service known as Ethernet Tree (E-Tree) [MEF6.1]. In an E- known as Ethernet-Tree (E-Tree) [MEF6.1]. In an E-Tree service, a
Tree service, a customer site that is typically represented by an customer site that is typically represented by an Attachment Circuit
Attachment Circuits (AC) (e.g., a 802.1Q VLAN tag but may also be (AC) (e.g., an 802.1Q VLAN tag [IEEE.802.1Q]), is labeled as either a
represented by a MAC address) is labeled as either a Root or a Leaf Root or a Leaf site. A customer site may also be represented by a
site. Root sites can communicate with all other customer sites (both Media Access Control (MAC) address along with a VLAN tag. Root sites
Root and Leaf sites). However, Leaf sites can communicate with Root can communicate with all other customer sites (both Root and Leaf
sites but not with other Leaf sits. In this document unless sites). However, Leaf sites can communicate with Root sites but not
explicitly mentioned otherwise, a site is always represented by an with other Leaf sites. In this document, unless explicitly mentioned
AC. otherwise, a site is always represented by an 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. This 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
networks in addition to multipoint-to-multipoint Ethernet LAN (E-LAN) networks and supplements the multipoint-to-multipoint Ethernet LAN
services specified in [RFC7432] and [RFC7623]. (E-LAN) services specified in [RFC7432] and [RFC7623].
[RFC7432] defines EVPN, a solution for multipoint L2VPN services with [RFC7432] defines EVPN, a solution for multipoint Layer 2 Virtual
advanced multi-homing capabilities, using BGP for distributing Private Network (L2VPN) services with advanced multihoming
customer/client MAC address reach-ability information over the capabilities that uses BGP for distributing customer/client MAC
MPLS/IP network. [RFC7623] combines the functionality of EVPN with address reachability information over the MPLS/IP network. [RFC7623]
[802.1ah] Provider Backbone Bridging (PBB) for MAC address combines the functionality of EVPN with [IEEE.802.1ah] Provider
scalability. Backbone Bridging (PBB) for MAC address 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 EVPN [RFC7432] and
[RFC7432] and [RFC7623]) with some extensions to their procedures and PBB-EVPN [RFC7623] with some extensions to their procedures and BGP
BGP attributes. Such (PBB-)EVPN based solution can offer a more attributes. Such a solution based on PBB-EVPN or EVPN can offer a
efficient implementation of these functions than that of RFC7796, E- more efficient implementation of these functions than that of
Tree Support in Virtual Private LAN Service (VPLS). This efficiency [RFC7796], "Ethernet-Tree (E-Tree) Support in Virtual Private LAN
is achieved by performing filtering of unicast traffic at the ingress Service (VPLS)". This efficiency is achieved by performing filtering
PE nodes as opposed to egress filtering where the traffic is sent of unicast traffic at the ingress Provider Edge (PE) nodes as opposed
through the network and gets filtered and discarded at the egress PE to egress filtering where the traffic is sent through the network and
nodes. The details of this ingress filtering is described in section gets filtered and discarded at the egress PE nodes. The details of
3.1. Since this document specifies a solution based on [RFC7432], it this ingress filtering are described in Section 4.1. Since this
requires the readers to have the knowledge of [RFC7432] as document specifies a solution based on [RFC7432], the knowledge of
prerequisite. This document makes use of the most significant bit of that document is a prerequisite. This document makes use of the most
the "Tunnel Type" field (in PMSI Tunnel Attribute) governed by the significant bit of the Tunnel Type field (in the PMSI Tunnel
IANA registry created by RFC7385, and hence updates RFC7385 attribute) governed by the IANA registry created by [RFC7385]; hence,
accordingly. Section 2 discusses E-Tree scenarios. Section 3 and 4 it updates [RFC7385] accordingly. Section 3 discusses E-Tree
describe E-Tree solutions for EVPN and PBB-EVPN respectively, and scenarios, Sections 4 and 5 describe E-Tree solutions for EVPN and
section 5 covers BGP encoding for E-Tree solutions. PBB-EVPN (respectively), and Section 6 covers BGP encoding for E-Tree
solutions.
1.1 Specification of Requirements 2. Terminology
2.1. Specification of Requirements
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", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in RFC 2119 [KEYWORDS]. "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.2 Terminology 2.2. Terms and Abbreviations
Broadcast Domain: In a bridged network, the broadcast domain Broadcast Domain: In a bridged network, the broadcast domain
corresponds to a Virtual LAN (VLAN), where a VLAN is typically corresponds to a Virtual LAN (VLAN), where a VLAN is typically
represented by a single VLAN ID (VID) but can be represented by represented by a single VLAN ID (VID) but can be represented by
several VIDs where Shared VLAN Learning (SVL) is used per [802.1Q]. several VIDs where Shared VLAN Learning (SVL) is used per
[IEEE.802.1ah].
Bridge Table: An instantiation of a broadcast domain on a MAC-VRF. Bridge Table: An instantiation of a broadcast domain on a MAC-VRF.
CE: Customer Edge device, e.g., a host, router, or switch. CE: A Customer Edge device, e.g., a host, router, or switch.
EVI: An EVPN instance spanning the Provider Edge (PE) devices EVI: An EVPN Instance spanning the Provider Edge (PE) devices
participating in that EVPN. participating in 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 a PE. Control (MAC) addresses on a PE.
Ethernet Segment (ES): When a customer site (device or network) is ES: When a customer site (device or network) is connected to one or
connected to one or more PEs via a set of Ethernet links, then that more PEs via a set of Ethernet links, then that set of links is
set of links is referred to as an 'Ethernet segment'. referred to as an "Ethernet Segment".
Ethernet Segment Identifier (ESI): A unique non-zero identifier that ESI: An Ethernet Segment Identifier is a unique non-zero identifier
identifies an Ethernet segment is called an 'Ethernet Segment that identifies an ES.
Identifier'.
Ethernet Tag: An Ethernet tag identifies a particular broadcast Ethernet Tag: An Ethernet Tag identifies a particular broadcast
domain, e.g., a VLAN. An EVPN instance consists of one or more domain, e.g., a VLAN. An EVPN instance consists of one or more
broadcast domains. broadcast domains.
P2MP: Point to Multipoint. P2MP: Point-to-Multipoint.
PE: Provider Edge device. PE: Provider Edge device.
2 E-Tree Scenarios 3. E-Tree Scenarios
This document categorizes E-Tree scenarios into the following three This document categorizes E-Tree scenarios into the following three
scenarios, depending on the nature of the Root/Leaf site association: categories, depending on the nature of the Root/Leaf site
association:
- Either Leaf or Root site(s) per PE Scenario 1: either Leaf or Root site(s) per PE;
- Either Leaf or Root site(s) per Attachment Circuit (AC) Scenario 2: either Leaf or Root site(s) per Attachment Circuit (AC);
or,
- Either Leaf or Root site(s) per MAC address Scenario 3: either Leaf or Root site(s) per MAC address.
2.1 Scenario 1: Leaf or Root Site(s) per PE 3.1. 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|
| +---+ | +------+ | +---+ | (Leaf) +---+ | +---+ | +------+ | +---+ | (Leaf) +---+
+---------+ +---------+ +---------+ +---------+
Figure 1: Scenario 1 Figure 1: Scenario 1
In this scenario, tailored BGP Route Target (RT) import/export In this scenario, tailored BGP Route Target (RT) import/export
policies among the PEs belonging to the same EVI can be used to policies among the PEs belonging to the same EVI can be used to
prevent the communications among Leaf PEs. To prevent the prevent communication among Leaf PEs. To prevent communication among
communications among Leaf ACs connected to the same PE and belonging Leaf ACs connected to the same PE and belonging to the same EVI,
to the same EVI, split-horizon filtering is used to block traffic split-horizon filtering is used to block traffic from one Leaf AC to
from one Leaf AC to another Leaf AC on a MAC-VRF for a given E-Tree another Leaf AC on a MAC-VRF for a given E-Tree EVI. The purpose of
EVI. The purpose of this topology constraint is to avoid having PEs this topology constraint is to avoid having PEs with only Leaf sites
with only Leaf sites importing and processing BGP MAC routes from importing and processing BGP MAC routes from each other. To support
each other. To support such topology constrain in EVPN, two BGP such a topology constraint in EVPN, two BGP RTs are used for every
Route-Targets (RTs) are used for every EVPN Instance (EVI): one RT is EVI: one RT is associated with the Root sites (Root ACs) and the
associated with the Root sites (Root ACs) and the other is associated other is associated with the Leaf sites (Leaf ACs). On a per-EVI
with the Leaf sites (Leaf ACs). On a per EVI basis, every PE exports basis, every PE exports the single RT associated with its type of
the single RT associated with its type of site(s). Furthermore, a PE site(s). Furthermore, a PE with a Root site(s) imports both Root and
with Root site(s) imports both Root and Leaf RTs, whereas a PE with Leaf RTs, whereas a PE with a 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 approach B in Scenario
scenario 2 (described below) needs to be used. 2 (described below) needs to be used.
2.2 Scenario 2: Leaf or Root Site(s) per AC 3.2. 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) +---+
+---------+ +---------+ +---------+ +---------+
Figure 2: Scenario 2 Figure 2: Scenario 2
In this scenario, just like the previous scenario (in section 2.1), In this scenario, (as in Scenario 1 Section 3.1), two RTs (one for
two Route Targets (one for Root and another for Leaf) can be used. Root and another for Leaf) can be used. However, the difference is
However, the difference is that on a PE with both Root and Leaf ACs, that on a PE with both Root and Leaf ACs, all remote MAC routes are
all remote MAC routes are imported and thus there needs to be a way imported; thus, in order to apply the proper ingress filtering, there
to differentiate remote MAC routes associated with Leaf ACs versus needs to be a way to differentiate remote MAC routes associated with
the ones associated with Root ACs in order to apply the proper Leaf ACs versus the ones associated with Root ACs.
ingress filtering.
In order to recognize the association of a destination MAC address to In order to recognize the association of a destination MAC address to
a Leaf or Root AC and thus support ingress filtering on the ingress a Leaf or Root AC and, thus, support ingress filtering on the ingress
PE with both Leaf and Root ACs, MAC addresses need to be colored with PE with both Leaf and Root ACs, MAC addresses need to be colored with
Root or Leaf indication before advertisements to other PEs. There are a Root or Leaf-Indication before advertising to other PEs. There are
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), or
B) To allow for a single RT be used per EVI just like [RFC7432] and (B) to allow for a single RT to be used per EVI, just like
thus color MAC addresses via a "color" flag in a new extended [RFC7432], and, thus, color MAC addresses via a "color" flag in
community as detailed in section 5.1. a new extended community as detailed in Section 6.1.
Approach (A) would require the same data plane enhancements as Approach A would require the same data-plane enhancements as approach
approach (B) if MAC-VRF and bridge tables used per VLAN, are to B if MAC-VRF and bridge tables used per VLAN are to remain consistent
remain consistent with [RFC7432] (section 6). In order to avoid data- with Section 6 of [RFC7432]. In order to avoid data-plane
plane enhancements for approach (A), multiple bridge tables per VLAN enhancements for approach A, multiple bridge tables per VLAN may be
may be considered; however, this has major drawbacks as described in considered; however, this has major drawbacks (as described in
appendix-A and thus is not recommended. Appendix A); thus, it is not recommended.
Given that both approaches (A) and (B) would require the same data- Given that both approaches A and B would require the same data-plane
plane enhancements, approach (B) is chosen here in order to allow for enhancements, approach B is chosen here in order to allow for RT
RT usage consistent with baseline EVPN [RFC7432] and for better usage consistent with baseline EVPN [RFC7432] and for better
generality. It should be noted that if one wants to use RT generality. It should be noted that if one wants to use RT
constraints in order to avoid MAC advertisements associated with a constraints in order to avoid MAC advertisements associated with a
Leaf AC to PEs with only Leaf ACs, then two RTs (one for Root and Leaf AC to PEs with only Leaf ACs, then two RTs (one for Root and
another for Leaf) can still be used with approach (B); however, in another for Leaf) can still be used with approach B; however, in such
such applications Leaf/Root RTs will be used to constrain MAC applications, Leaf/Root RTs will be used to constrain MAC
advertisements and they are not used to color the MAC routes for advertisements and are not used to color the MAC routes for ingress
ingress filtering - i.e., in approach (B), the coloring is always filtering (i.e., in approach B, the coloring is always done via the
done via the new extended community. new extended community).
If, for a given EVI, a significant number of PEs have both Leaf and If, for a given EVI, a significant number of PEs have both Leaf and
Root sites attached (even though they may start as Root-only or Leaf- Root sites attached (even though they may start as Root-only or Leaf-
only PEs), then a single RT per EVI should be used. The reason for only PEs), then a single RT per EVI should be used. The reason for
such recommendation is to alleviate the configuration overhead such a recommendation is to alleviate the configuration overhead
associated with using two RTs per EVI at the expense of having some associated with using two RTs per EVI at the expense of 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 3.3. 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 on an AC and a PE may receive traffic from both Root and
sites on a single Attachment Circuit (AC) of an EVI. This scenario is Leaf sites on that AC for an EVI. This scenario is not covered in
not covered in either [RFC7387] or [MEF6.1]; however, it is covered either [RFC7387] or [MEF6.1]; however, it is covered in this document
in this document for the sake of completeness. In this scenario, for the sake of completeness. In this scenario, since an AC carries
since an AC carries traffic from both Root and Leaf sites, the traffic from both Root and Leaf sites, the granularity at which Root
granularity at which Root or Leaf sites are identified is on a per or Leaf sites are identified is on a per-MAC-address basis. This
MAC address. This scenario is considered in this document for EVPN scenario is considered in this document for EVPN service with only
service with only known unicast traffic because the Designated known unicast traffic because the Designated Forwarder (DF) filtering
Forwarding (DF) filtering per [RFC7432] would not be compatible with per [RFC7432] would not be compatible with the required egress
the required egress filtering - i.e., Broadcast, Unknown, and filtering; that is, Broadcast, Unknown Unicast, and Multicast (BUM)
Multicast (BUM) traffic is not supported in this scenario and it is traffic is not supported in this scenario; it is dropped by the
dropped by the ingress PE. ingress PE.
For this scenario, the approach B in scenario 2 (described above) is For this scenario, the approach B in Scenario 2 is used in order to
used in order to allow for single RT usage by service providers. allow for single RT usage by service providers.
+---------+ +---------+ +---------+ +---------+
| PE1 | | PE2 | | PE1 | | PE2 |
+---+ | +---+ | +------+ | +---+ | +---+ +---+ | +---+ | +------+ | +---+ | +---+
|CE1+-----AC1----+--+ | | | | | | +--+-----AC2----+CE2| |CE1+-----AC1----+--+ | | | | | | +--+-----AC2----+CE2|
+---+ (Root) | | E | | | MPLS | | | E | | (Leaf/Root)+---+ +---+ (Root) | | E | | | MPLS | | | E | | (Leaf/Root)+---+
| | V | | | /IP | | | V | | | | V | | | /IP | | | V | |
| | I | | | | | | I | | +---+ | | I | | | | | | I | | +---+
| | | | | | | | +--+-----AC3----+CE3| | | | | | | | | +--+-----AC3----+CE3|
| +---+ | +------+ | +---+ | (Leaf) +---+ | +---+ | +------+ | +---+ | (Leaf) +---+
+---------+ +---------+ +---------+ +---------+
Figure 3: Scenario 3 Figure 3: Scenario 3
In conclusion, the approach B in scenario 2 is the recommended In conclusion, the approach B in scenario 2 is the recommended
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 4. Operation for EVPN
[RFC7432] defines the notion of Ethernet Segment Identifier (ESI) [RFC7432] defines the notion of the 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 known unicast traffic, additional extensions to
is needed (i.e., a new BGP Extended Community for Leaf indication [RFC7432] are needed (i.e., a new BGP extended community for Leaf-
described in section 5.1) in order to enable ingress filtering as Indication described in Section 6.1) in order to enable ingress
described in detail in the following sections. filtering as described in detail in the following sections.
3.1 Known Unicast Traffic 4.1. Known Unicast Traffic
Since in EVPN, MAC learning is performed in the control plane via 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. Because of this, the filtering needed
for known unicast traffic can be performed at the ingress PE, thus by an E-Tree service for known unicast traffic can be performed at
providing very efficient filtering and avoiding sending known unicast the ingress PE, thus providing very efficient filtering and avoiding
traffic over the MPLS/IP core to be filtered at the egress PE as done sending known unicast traffic over the MPLS/IP core to be filtered at
in traditional E-Tree solutions - i.e., E-Tree for VPLS [RFC7796]. the egress PE, as is done 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 a 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 3.
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; that is, 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 that indicates whether or not the
MAC is associated with a Leaf site or not. The ingress PE cross- target MAC is associated with a Leaf site. 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.
In situation where MAC moves are allowed among Leaf and Root sites In a situation where MAC moves are allowed among Leaf and Root sites
(e.g., non-static MAC), PEs can receive multiple MAC/IP (e.g., non-static MAC), PEs can receive multiple MAC/IP Advertisement
advertisements routes for the same MAC address with different routes for the same MAC address with different Root or Leaf-
Leaf/Root indications (and possibly different ESIs for multi-homing Indications (and possibly different ESIs for multihoming scenarios).
scenarios). In such situations, MAC mobility procedures (section 15 In such situations, MAC mobility procedures (see Section 15 of
of [RFC7432]) take precedence to first identify the location of the [RFC7432]) take precedence to first identify the location of the MAC
MAC before associating that MAC with a Root or a Leaf site. 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 (see
5.1]. This new Extended Community MUST be advertised with MAC/IP Section 6.1). This new extended community MUST be advertised with
Advertisement routes learned from a Leaf site. Besides MAC/IP MAC/IP Advertisement routes learned from a Leaf site. Besides MAC/IP
Advertisement route, no other EVPN routes are required to carry this Advertisement routes, no other EVPN routes are required to carry this
new extended community. new extended community for the purpose of known unicast traffic.
3.2 Broadcast, Unkonwn, and Multicast (BUM) Traffic 4.2. BUM Traffic
This specification does not provide support for filtering BUM This specification does not provide support for filtering Broadcast,
(Broadcast, Unknown, and Multicast) traffic on the ingress PE; due to Unknown Unicast, and Multicast (BUM) traffic on the ingress PE; due
the multi-destination nature of BUM traffic, is is not possible to to the multidestination nature of BUM traffic, it is not possible to
perform filtering of the same on the ingress PE. As such, the perform filtering of the same on the ingress PE. As such, the
solution relies on egress filtering. In order to apply the proper solution relies on egress filtering. In order to apply the proper
egress filtering, which varies based on whether a packet is sent from egress filtering, which varies based on whether a packet is sent from
a Leaf AC or a Root AC, the MPLS-encapsulated frames MUST be tagged a Leaf AC or a Root AC, the MPLS-encapsulated frames MUST be tagged
with an indication when they originated from a Leaf AC - i.e., to be with an indication of when they originated from a Leaf AC (i.e., to
tagged with a Leaf label as specified in section 5.1. This Leaf label be tagged with a Leaf label as specified in Section 6.1). This Leaf
allows for disposition PE (e.g., egress PE) to perform the necessary label allows for disposition PE (e.g., egress PE) to perform the
egress filtering function in data-plane similar to ESI label in necessary egress filtering function in a data plane similar to the
[RFC7432]. The allocation of the Leaf label is on a per PE basis ESI label in [RFC7432]. The allocation of the Leaf label is on a
(e.g., independent of ESI and EVI) as descried in the following per-PE basis (e.g., independent of ESI and EVI) as described in the
sections. following sections.
The Leaf label can be upstream assigned for P2MP LSP or downstream The Leaf label can be upstream assigned for Point-to-Multipoint
assigned for ingress replication tunnels. The main difference between (P2MP) Label Switched Path (LSP) or downstream assigned for Ingress
downstream and upstream assigned Leaf label is that in case of Replication tunnels. The main difference between a downstream- and
downstream assigned not all egress PE devices need to receive the upstream-assigned Leaf label is that, in the case of downstream-
label in MPLS encapsulated BUM packets just like ESI label for assigned Leaf labels, not all egress PE devices need to receive the
ingress replication procedures defined in [RFC7432]. label in MPLS-encapsulated BUM packets, just like the ESI label for
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
intra-PE forwarding among its Leaf ACs. This intra-PE split-horizon intra-PE forwarding among its Leaf ACs. This intra-PE split-horizon
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 [IEEE.802.1Q]).
for identifying Root or Leaf sites such as the use of source MAC Other mechanisms for identifying Root or Leaf sites, such as the use
address of the receiving frame are optional. The scenarios below are of the source MAC address of the receiving frame, are optional. The
described in context of Root/Leaf AC; however, they can be extended scenarios below are described in context of a Root/Leaf AC, however,
to Root/Leaf MAC address if needed. they can be extended to the Root/Leaf MAC address if needed.
3.2.1 BUM Traffic Originated from a Single-homed Site on a Leaf AC 4.2.1. 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 (see Section 6.1), which indicates a
This Leaf label, used for single-homing scenarios, is not on a per ES Leaf site. This Leaf label, used for single-homing scenarios, is not
basis but rather on a per PE basis - i.e., a single Leaf MPLS label on a per-ES basis but rather on a per PE basis (i.e., a single Leaf
is used for all single-homed ES's on that PE. This Leaf label is MPLS label is used for all single-homed ESs on that PE). This Leaf
advertised to other PE devices, using the E-Tree Extended Community label is advertised to other PE devices using the E-Tree extended
(section 5.1) along with an Ethernet Auto-discovery per ES (EAD-ES) community (see Section 6.1) along with an Ethernet Auto-Discovery per
route with ESI of zero and a set of Route Targets (RTs) corresponding ES (EAD-ES) route with an ESI of zero and a set of RTs corresponding
to all EVIs on the PE where each EVI has at least one Leaf site. to all EVIs on the PE where each EVI has at least one Leaf site.
Multiple EAD-ES routes will need to be advertised if the number of Multiple EAD-ES routes will need to be advertised if the number of
Route Targets (RTs) that need to be carried exceed the limit on a RTs that need to be carried exceed the limit on a single route per
single route per [RFC7432]. The ESI for the EAD-ES route is set to [RFC7432]. The ESI for the EAD-ES route is set to zero to indicate
zero to indicate single-homed sites. 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 4.2.2. 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 or Leaf labels
label and it operates per [RFC7432] procedures. and it operates per the procedures in [RFC7432].
3.2.3 BUM Traffic Originated from a Multi-homed Site on a Leaf AC 4.2.3. BUM Traffic Originated from a Multihomed 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 a 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/
Root/Leaf designation on all PEs on the same ES. Furthermore, it is 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 (i.e., the service
is EVPN L2 and not EVPN IRB [EVPN-IRB]. IRB use cases described in is EVPN L2 and not EVPN Integrated Routing and Bridging (IRB)
[EVPN-IRB] are outside the scope of this document. [EVPN-INTEGRATED]). IRB use cases described in [EVPN-INTEGRATED] 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 a Leaf label as described
section 3.2.1. This label is sufficient in providing the necessary in Section 4.2.1. This label is sufficient in providing the
egress filtering of BUM traffic from getting sent to Leaf ACs necessary egress filtering of BUM traffic from getting sent to Leaf
including the Leaf AC on the same Ethernet Segment. ACs, including the Leaf AC on the same ES.
3.2.4 BUM Traffic Originated from a Multi-homed Site on a Root AC 4.2.4. BUM Traffic Originated from a Multihomed 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 follow 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; that is, existing procedures for BUM traffic in [RFC7432]
are sufficient and there is no need to add a Leaf label. are sufficient and there is no need to add a Leaf label.
3.3 E-Tree Traffic Flows for EVPN 4.3. E-Tree Traffic Flows for EVPN
Per [RFC7387], a generic E-Tree service supports all of the following Per [RFC7387], a generic E-Tree service supports all of the following
traffic flows: traffic flows:
- Known unicast traffic from Root to Roots & Leaf - known unicast traffic from Root to Roots & Leafs
- Known unicast traffic from Leaf to Root
- BUM traffic from Root to Roots & Leafs - known unicast traffic from Leaf to Roots
- BUM traffic from Leaf to Roots
- BUM traffic from Root to Roots & Leafs
- BUM traffic from Leaf to Roots
A particular E-Tree service may need to support all of the above A particular E-Tree service may need to support all of the above
types of flows or only a select subset, depending on the target types of flows or only a select subset, depending on the target
application. In the case where only multicast and broadcast flows application. In the case where only multicast and broadcast flows
need to be supported, the L2VPN PEs can avoid performing any MAC need to be supported, the L2VPN PEs can avoid performing any MAC
learning function. learning function.
The following subsections will describe the operation of EVPN to The following subsections will describe the operation of EVPN to
support E-Tree service with and without MAC learning. support E-Tree service with and without MAC learning.
3.3.1 E-Tree with MAC Learning 4.3.1. E-Tree with MAC Learning
The PEs implementing an E-Tree service must perform MAC learning when The PEs implementing an E-Tree service must perform MAC learning when
unicast traffic flows must be supported among Root and Leaf sites. In unicast traffic flows must be supported among Root and Leaf sites.
this case, the PE(s) with Root sites performs MAC learning in the In this case, the PE(s) with Root sites performs MAC learning in the
data-path over the Ethernet Segments, and advertises reachability in data path over the ESs and advertises reachability in EVPN MAC/IP
EVPN MAC/IP Advertisement Routes. These routes will be imported by Advertisement routes. These routes will be imported by all PEs for
all PEs for that EVI (i.e., PEs that have Leaf sites as well as PEs that EVI (i.e., PEs that have Leaf sites as well as PEs that have
that have Root sites). Similarly, the PEs with Leaf sites perform MAC Root sites). Similarly, the PEs with Leaf sites perform MAC learning
learning in the data-path over their Ethernet Segments, and advertise in the data path over their ESs and advertise reachability in EVPN
reachability in EVPN MAC/IP Advertisement Routes. For scenarios where MAC/IP Advertisement routes. For scenarios where two different RTs
two different RTs are used per EVI (one to designate Root site and are used per EVI (one to designate a Root site and another to
another to designate Leaf site), the MAC/IP Advertisement routes are designate a Leaf site), the MAC/IP Advertisement routes are imported
imported only by PEs with at least one Root site in the EVI - i.e., a only by PEs with at least one Root site in the EVI (i.e., a PE with
PE with only Leaf sites will not import these routes. PEs with Root only Leaf sites will not import these routes). PEs with Root and/or
and/or Leaf sites may use the Ethernet Auto-discovery per EVI (EAD- Leaf sites may use the Ethernet Auto-Discovery per EVI (EAD-EVI)
EVI) routes for aliasing (in the case of multi-homed segments) and routes for aliasing (in the case of multihomed segments) and EAD-ES
EAD-ES routes for mass MAC withdrawal per [RFC7432]. 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 (see 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 describe
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/
multicast/broadcast traffic from Leaf PEs toward Root PEs, then broadcast traffic from Leaf PEs toward Root PEs, then Ingress
ingress replication tunnels from Leaf PEs toward Root PEs should be 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
transmit direction from itself to Leaf PEs and at the same time it in the transmit direction from itself to Leaf PEs, and, at the same
wants to support ingress-replication tunnels in receive direction, time, it wants to support Ingress Replication tunnels in the receive
the Root PE can signal it efficiently by using a new composite tunnel direction, the Root PE can signal it efficiently by using a new
type defined in section 5.2. This new composite tunnel type is composite tunnel type defined in Section 6.2. This new composite
advertised by the Root PE to simultaneously indicate a P2MP tunnel in tunnel type is advertised by the Root PE to simultaneously indicate a
transmit direction and an ingress-replication tunnel in the receive P2MP tunnel in the transmit direction and an Ingress Replication
direction for the BUM traffic. tunnel in the receive 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., Multipoint
TE) originated at the Leaf PEs may be used and thus there will be no LDP (mLDP) or RSVP-TE) originated at the Leaf PEs may be used; thus,
need to use the modified PMSI tunnel attribute and the composite there will be no need to use the modified PMSI Tunnel attribute and
tunnel type values defined in section 5.2. the composite tunnel type values defined in Section 6.2.
3.3.2 E-Tree without MAC Learning 4.3.2. 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. In such scenarios, Ethernet Tag route is used to support BUM traffic. In such
the small amount of unicast traffic (if any) is sent as part of BUM scenarios, the small amount of unicast traffic (if any) is sent as
traffic. 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 6.2 should be used.
4 Operation for PBB-EVPN 5. 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 or Leaf-Indication along with
B-MAC Advertisement route to indicate whether the associated B-MAC each Backbone MAC (B-MAC) Advertisement route to indicate whether the
address corresponds to a Root or a Leaf site. Just like the EVPN associated B-MAC address corresponds to a Root or a Leaf site. Just
case, the new E-Tree Extended Community defined in section [5.1] is like the EVPN case, the new E-Tree extended community defined in
advertised with each EVPN MAC/IP Advertisement route. Section 6.1 is 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 multihomed ES has both Root and Leaf sites
Leaf sites attached, two B-MAC addresses are advertised: one B-MAC attached, two B-MAC addresses are advertised: one B-MAC address is
address is per ES as specified in [RFC7623] and implicitly denoting per ES (as specified in [RFC7623]) and implicitly denotes Root, and
Root, and the other B-MAC address is per PE and explicitly denoting the other B-MAC address is per PE and explicitly denotes Leaf. The
Leaf. The former B-MAC address is not advertised with the E-Tree former B-MAC address is not advertised with the E-Tree extended
extended community but the latter B-MAC denoting Leaf is advertised community, but the latter B-MAC denoting Leaf is advertised with the
with the new E-Tree extended community where "Leaf-indication" flag new E-Tree extended community where a "Leaf-indication" flag is set.
is set. In multi-homing scenarios where an Ethernet Segment has both In multihoming scenarios where an ES has both Root and Leaf ACs, it
Root and Leaf ACs, it is assumed that while different ACs (VLANs) on is assumed that while different ACs (VLANs) on the same ES could have
the same ES could have different Root/Leaf designation (some being a different Root/Leaf designation (some being Roots and some being
Roots and some being Leafs), the same VLAN does have the same Leafs), the same VLAN does have the same Root/Leaf designation on all
Root/Leaf designation on all PEs on the same ES. Furthermore, it is PEs on the same ES. Furthermore, it is assumed that there is no
assumed that there is no forwarding among subnets - ie, the service forwarding among subnets (i.e., the service is L2 and not IRB). An
is L2 and not IRB. IRB use case is outside the scope of this 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 ES. The mechanism by which the PE identifies whether a given
whether a given frame originated from a Root or Leaf site on the frame originated from a Root or Leaf site on the segment is based on
segment is based on the Ethernet Tag associated with the frame. Other the Ethernet Tag associated with the frame. Other mechanisms of
mechanisms of identification, beyond the Ethernet Tag, are outside identification, beyond the Ethernet Tag, are outside the scope of
the scope of this document. 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
MAC address used for indicating Leaf sites can be the same for both B-MAC address used for indicating Leaf sites can be the same for both
single-homed and multi-homed segments. single-homed and multihomed segments.
4.1 Known Unicast Traffic 5.1. 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 [RFC7623] destination address lookup yields, in ingress PE, the Customer/Client MAC (C-MAC) [RFC7623] destination
addition to the target B-MAC address and forwarding adjacency, a flag address lookup yields, in addition to the target B-MAC address and
which indicates whether the target B-MAC is associated with a Root or forwarding adjacency, a flag that indicates whether the target B-MAC
a Leaf site. The ingress PE also checks the status of the originating is associated with a Root or a Leaf site. The ingress PE also checks
site, and if both are a Leaf, then the packet is not forwarded. the status of the originating site; if both are Leafs, then the
packet is not forwarded.
4.2 Broadcast, Unkonwn, and Multicast (BUM) Traffic 5.2. 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
advertised B-MAC is a Leaf, and the local Ethernet Segment is a Leaf
as well, then the source B-MAC address is added to its B-MAC list
used for egress filtering - i.e., to block traffic from that B-MAC
address.
- Otherwise, the B-MAC filtering list is not updated. - If the EVPN MAC/IP Advertisement route indicates that the
advertised B-MAC is a Leaf, and the local ES is a Leaf as well,
then the source B-MAC address is added to its B-MAC list used for
egress filtering (i.e., to block traffic from that B-MAC address).
Otherwise, the B-MAC filtering list is not updated.
- If the EVPN MAC/IP Advertisement route indicates that the - If the EVPN MAC/IP Advertisement route indicates that the
advertised B-MAC has changed its designation from a Leaf to a Root advertised B-MAC has changed its designation from a Leaf to a
and the local Ethernet Segment is a Leaf, then the source B-MAC Root, and the local ES is a Leaf, then the source B-MAC address is
address is removed from the B-MAC list corresponding to the local removed from the B-MAC list corresponding to the local ES used for
Ethernet Segment used for egress filtering - i.e., to unblock traffic egress filtering (i.e., to unblock traffic from that B-MAC
from that B-MAC address. address).
When the egress PE receives the packet, it examines the B-MAC source When the egress PE receives the packet, it examines the B-MAC source
address to check whether it should filter or forward the frame. Note address to check whether it should filter or forward the frame. Note
that this uses the same filtering logic as baseline [RFC7623] for an that this uses the same filtering logic as the split-horizon
ESI and does not require any additional flags in the data-plane. filtering described in Section 6.2.1.3 of [RFC7623] 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 4.2, the PE places all Leaf ESs of a given bridge
given bridge domain in a single split-horizon group in order to domain in a single split-horizon group in order to prevent intra-PE
prevent intra-PE forwarding among Leaf segments. This split-horizon forwarding among Leaf segments. This split-horizon function applies
function applies to BUM traffic as well as known-unicast traffic. to BUM traffic as well as known unicast traffic.
4.3 E-Tree without MAC Learning 5.3. 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 5.2 without the need for C-MAC learning (in the data plane)
component (C-bridge table) of PBB-EVPN PEs (at both ingress and in the I-component (C-bridge table) of PBB-EVPN PEs (at both ingress
egress PEs). and egress PEs).
5 BGP Encoding 6. BGP Encoding
This document defines a new BGP Extended Community for EVPN. This document defines a new BGP extended community for EVPN.
5.1 E-Tree Extended Community 6.1. E-Tree Extended Community
This Extended Community is a new transitive Extended Community This extended community is a new transitive extended community
[RFC4360] having a Type field value of 0x06 (EVPN) and the Sub-Type [RFC4360] having a Type field value of 0x06 (EVPN) and the Sub-Type
0x05. It is used for Leaf indication of known unicast and BUM 0x05. It is used for Leaf-Indication of known unicast and BUM
traffic. It indicates that the frame is originated from a Leaf site. traffic. It indicates that the frame is originated from a Leaf site.
The E-Tree Extended Community is encoded as an 8-octet value as The E-Tree extended community is encoded as an 8-octet value as
follows: follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=0x06 | Sub-Type=0x05 | Flags(1 Octet)| Reserved=0 | | Type=0x06 | Sub-Type=0x05 | Flags(1 Octet)| Reserved=0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved=0 | Leaf Label | | Reserved=0 | Leaf Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: E-Tree Extended Community Figure 4: E-Tree Extended Community
The Flags field has the following format: The Flags field has the following format:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| MBZ |L| (MBZ = Must Be Zero) | MBZ |L| (MBZ = MUST Be Zero)
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
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 the flag bits
reserved and should be set to zero. are reserved and should be set to zero.
When this Extended Community (EC) is advertised along with MAC/IP When this extended community is advertised along with the MAC/IP
Advertisement route (for known unicast traffic) per section 3.1, the Advertisement route (for known unicast traffic) per Section 4.1, the
Leaf-Indication flag MUST be set to one and Leaf Label SHOULD be set Leaf-Indication flag MUST be set to one and the Leaf label SHOULD be
to zero. The receiving PE MUST ignore Leaf Label and only processes set to zero. The receiving PE MUST ignore Leaf label and only
Leaf-Indication flag. A value of zero for Leaf-Indication flag is process the Leaf-Indication flag. A value of zero for the Leaf-
invalid when sent along with MAC/IP advertisement route and an error Indication flag is invalid when sent along with a MAC/IP
should be logged. Advertisement route, and an error should be logged.
When this EC is advertised along with EAD-ES route (with ESI of zero) When this extended community is advertised along with the EAD-ES
for BUM traffic to enable egress filtering on disposition PEs per route (with an ESI of zero) for BUM traffic to enable egress
sections 3.2.1 and 3.2.3, the Leaf Label MUST be set to a valid MPLS filtering on disposition PEs per Sections 4.2.1 and 4.2.3, the Leaf
label (i.e., non-reserved assigned MPLS label [RFC3032]) and the label MUST be set to a valid MPLS label (i.e., a non-reserved,
Leaf-Indication flag SHOULD be set to zero. The value of the 20-bit assigned MPLS label [RFC3032]) and the Leaf-Indication flag SHOULD be
MPLS label is encoded in the high-order 20 bits of the Leaf Label set to zero. The value of the 20-bit MPLS label is encoded in the
field. The receiving PE MUST ignore the Leaf-Indication flag. A non- high-order 20 bits of the Leaf label field. The receiving PE MUST
valid MPLS label when sent along with the EAD-ES route, should be ignore the Leaf-Indication flag. A non-valid MPLS label, when sent
ignored and logged as an error. along with the EAD-ES route, should be ignored and logged as an
error.
The reserved bits SHOULD be set to zero by the transmitter and MUST 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 6.2. PMSI Tunnel Attribute
[RFC6514] defines PMSI Tunnel attribute which is an optional [RFC6514] defines the 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) |
+---------------------------------+ +-------------------------------------------+
| Tunnel Type (1 octet) | | Tunnel Type (1 octet) |
+---------------------------------+ +-------------------------------------------+
| Ingress Replication MPLS Label | | Ingress Replication MPLS Label (3 octets) |
| (3 octets) | +-------------------------------------------+
+---------------------------------+ | Tunnel Identifier (variable) |
| Tunnel Identifier (variable) | +-------------------------------------------+
+---------------------------------+
Figure 5: PMSI Tunnel Attribute Table 1: 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 an
label to the Tunnel Identifier field of PMSI Tunnel attribute as MPLS label to the Tunnel Identifier field of the PMSI Tunnel
detailed below. All other fields remain as defined in [RFC6514]. attribute, as detailed below. All other fields remain as defined in
Composite tunnel type is advertised by the Root PE to simultaneously [RFC6514]. Composite tunnel type is advertised by the Root PE to
indicate a non-(ingress replication) tunnel (e.g., P2MP tunnel) in simultaneously indicate a non-Ingress-Replication tunnel (e.g., P2MP
transmit direction and an ingress-replication tunnel in the receive tunnel) in the transmit direction and an Ingress Replication tunnel
direction for the BUM traffic. in the receive direction for the BUM traffic.
When receiver ingress-replication labels are needed, the high-order When receiver Ingress Replication labels are needed, the high-order
bit 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 treat PEs that don't understand the new meaning of the high-order bit treat
the tunnel type as an undefined tunnel type and treat the PMSI tunnel the Tunnel Type as an undefined Tunnel Type and treat the PMSI Tunnel
attribute as a malformed attribute [RFC6514]. That is why the attribute as a malformed attribute [RFC6514]. That is why 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 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. A PE
PE that receives a PMSI Tunnel attribute with such information, that receives a PMSI Tunnel attribute with such information considers
considers it as malformed and it SHOULD treat this Update as though it malformed, and it SHOULD treat this Update as though all the
all the routes contained in this Update had been withdrawn per routes contained in this Update had been withdrawn per Section 6 of
section 5 of [RFC6514]. [RFC6514].
6 Acknowledgement
We would like to thank Eric Rosen, Jeffrey Zhang, Wen Lin, Aldrin
Issac, Wim Henderickx, Dennis Cai, and Antoni Przygienda for their
valuable comments and contributions. The authors would also like to
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 an also applicable here. Furthermore, this document provides an
additional security check by allowing sites (or ACs) of an EVPN additional security check by allowing sites (or ACs) of an EVPN
instance to be designated as "Root" or "Leaf" by the network instance to be designated as a "Root" or "Leaf" by the network
operator/ service provider and thus preventing any traffic exchange operator / service provider and thus prevent 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. Since by unicast traffic and egress filtering for BUM traffic. Since (by
default and for the purpose of backward compatibility, an AC that 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 doesn't have a Leaf designation is considered a Root AC, in order to
to avoid any traffic exchange among Leaf ACs, the operator SHOULD avoid any traffic exchange among Leaf ACs, the operator SHOULD
configure the AC with a proper role (Leaf or Root) before activating configure the AC with a proper role (Leaf or Root) before activating
the AC. the AC.
8 IANA Considerations 8. IANA Considerations
IANA has allocated value 5 in the "EVPN Extended Community Sub-Types" IANA has allocated sub-type value 5 in the "EVPN Extended Community
registry defined in [RFC7153] as follow: Sub-Types" registry defined in [RFC7153] as follows:
SUB-TYPE VALUE NAME Reference SUB-TYPE VALUE NAME Reference
-------------- ------------------------- -------------
0x05 E-Tree Extended Community This document 0x05 E-Tree Extended Community This document
This document creates a one-octet registry called "E-Tree Flags". This document creates a one-octet registry called "E-Tree Flags".
New registrations will be made through the "RFC Required" procedure New registrations will be made through the "RFC Required" procedure
defined in [RFC8126]. Initial registrations are as follows: defined in [RFC8126]. Initial registrations are as follows:
bit Name Reference Bit Name Reference
---- -------------- -------------
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 (PMSI) Tunnel Types" registry in
registry in the "Border Gateway Protocol (BGP) Parameters" registry the "Border Gateway Protocol (BGP) Parameters" registry has been
needs to be updated to reflect the use of the most significant bit as updated to reflect the use of the most significant bit as the
"Composite Tunnel" bit (section 5.2). "composite tunnel" bit (see Section 6.2).
For this purpose, this document updates [RFC7385] by changing the For this purpose, this document updates [RFC7385] by changing the
previously unassigned values (i.e., 0x08 - 0xFA) as follow: previously unassigned values (i.e., 0x08 - 0xFA) as follows:
Value Meaning Reference Value Meaning Reference
0x08-0x7A Unassigned --------- ----------------------------- --------------
0x7B-0x7E Experimental this document 0x0C-0x7A Unassigned
0x7F Reserved this document 0x7B-0x7E Experimental This Document
0x80-0xFA Reserved for Composite tunnel this document 0x7F Reserved 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 0x08-0x7A is per IETF Review The allocation policy for values 0x08-0x7A is per IETF Review
[RFC8126]. The range for experimental has been expanded to include [RFC8126]. The range for "Experimental" has been expanded to include
the previously assigned range of 0xFB-0xFE and the new range of 0x7B- the previously assigned range of 0xFB-0xFE and the new range of
0x7E. The value in these ranges are not to be assigned. The value 0x7B-0x7E. The values in these ranges are not to be assigned. The
0x7F which is the mirror image of (0xFF) is reserved in this value 0x7F, which is the mirror image of (0xFF), is reserved in this
document. document.
9 References 9. References
9.1 Normative References 9.1. Normative References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate [MEF6.1] MEF Forum, "Ethernet Services Definitions - Phase 2",
Requirement Levels", BCP 14, RFC 2119, March 1997. MEF 6.1, April 2008, <https://mef.net/PDF_Documents/
technical-specifications/MEF6-1.pdf>.
[RFC8126] Cotton et al, "Guidelines for Writing an IANA [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Considerations Section in RFCs", June, 2017. Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC7387] Key et al., "A Framework for E-Tree Service over MPLS [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Network", October 2014. Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
February 2006, <https://www.rfc-editor.org/info/rfc4360>.
[MEF6.1] Metro Ethernet Forum, "Ethernet Services Definitions - Phase [RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP
2", MEF 6.1, April 2008, https://mef.net/PDF_Documents/technical- Encodings and Procedures for Multicast in MPLS/BGP IP
specifications/MEF6-1.pdf VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012,
<https://www.rfc-editor.org/info/rfc6514>.
[RFC7432] Sajassi et al., "BGP MPLS Based Ethernet VPN", February, [RFC7153] Rosen, E. and Y. Rekhter, "IANA Registries for BGP
2015. Extended Communities", RFC 7153, DOI 10.17487/RFC7153,
March 2014, <https://www.rfc-editor.org/info/rfc7153>.
[RFC7623] Sajassi et al., "Provider Backbone Bridging Combined with [RFC7385] Andersson, L. and G. Swallow, "IANA Registry for
Ethernet VPN (PBB-EVPN)", September, 2015. P-Multicast Service Interface (PMSI) Tunnel Type Code
Points", RFC 7385, DOI 10.17487/RFC7385, October 2014,
<https://www.rfc-editor.org/info/rfc7385>.
[RFC7385] Andersson et al., "IANA Registry for P-Multicast Service [RFC7387] Key, R., Ed., Yong, L., Ed., Delord, S., Jounay, F., and
Interface (PMSI) Tunnel Type Code Points", October, 2014. L. Jin, "A Framework for Ethernet Tree (E-Tree) Service
over a Multiprotocol Label Switching (MPLS) Network",
RFC 7387, DOI 10.17487/RFC7387, October 2014,
<https://www.rfc-editor.org/info/rfc7387>.
[RFC7153] Rosen et al., "IANA Registries for BGP Extended [RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Communities", March, 2014. Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
2015, <https://www.rfc-editor.org/info/rfc7432>.
[RFC6514] Aggarwal et al., "BGP Encodings and Procedures for [RFC7623] Sajassi, A., Ed., Salam, S., Bitar, N., Isaac, A., and W.
Multicast in MPLS/BGP IP VPNs", February, 2012. Henderickx, "Provider Backbone Bridging Combined with
Ethernet VPN (PBB-EVPN)", RFC 7623, DOI 10.17487/RFC7623,
September 2015, <https://www.rfc-editor.org/info/rfc7623>.
[RFC4360] Sangli et al., "BGP Extended Communities Attribute", [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
February, 2006. Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
9.2 Informative References [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC4360] S. Sangli et al, "BGP Extended Communities Attribute", 9.2. Informative References
February, 2006.
[RFC3032] E. Rosen et al, "MPLS Label Stack Encoding", January 2001. [EVPN-INTEGRATED]
Sajassi, A., Salam, S., Thoria, S., Drake, J., Rabadan,
J., and L. Yong, "Integrated Routing and Bridging in
EVPN", Work in Progress, draft-ietf-bess-evpn-inter-
subnet-forwarding-03, February 2017.
[RFC7796] Y. Jiang et al, "Ethernet-Tree (E-Tree) Support in Virtual [IEEE.802.1ah]
Private LAN Service (VPLS)", March 2016. IEEE, "IEEE Standard for Local and metropolitan area
networks - Media Access Control (MAC) Bridges and Virtual
Bridged Local Area Networks", Clauses 25 and 26, IEEE
Std 802.1Q, DOI 10.1109/IEEESTD.2011.6009146.
[EVPN-IRB] A. Sajassi et al, "Integrated Routing and Bridging in [IEEE.802.1Q]
EVPN", draft-ietf-bess-evpn-inter-subnet-forwarding-03, February 8, IEEE, "IEEE Standard for Local and metropolitan area
2017. networks - Bridges and Bridged Networks - Media Access
Control (MAC) Bridges and Virtual Bridged Local Area
Networks", IEEE Std 802.1Q,
DOI 10.1109/IEEESTD.2011.6009146.
[802.1ah] IEEE, "IEEE Standard for Local and metropolitan area [RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
networks - Media Access Control (MAC) Bridges and Virtual Bridged Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Local Area Networks", Clauses 25 and 26, IEEE Std 802.1Q, DOI Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
10.1109/IEEESTD.2011.6009146. <https://www.rfc-editor.org/info/rfc3032>.
Appendix-A [RFC7796] Jiang, Y., Ed., Yong, L., and M. Paul, "Ethernet-Tree
(E-Tree) Support in Virtual Private LAN Service (VPLS)",
RFC 7796, DOI 10.17487/RFC7796, March 2016,
<https://www.rfc-editor.org/info/rfc7796>.
When two MAC-VRFs (two bridge tables per VLANs) are used for an E- Appendix A. Multiple Bridge Tables per E-Tree Service Instance
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. When two MAC-VRFs (two bridge tables per VLAN) are used for an E-Tree
service (one for Root ACs and another for Leaf ACs) on a given PE,
then the following complications in a 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 require either that two
be performed per MAC address in each direction in case of a miss, or lookups be performed per MAC address in each direction in case of a
duplicating many MAC addresses between the two bridge tables miss or that the duplication of many MAC addresses between the two
belonging to the same VLAN (same E-Tree instance). Unless two lookups bridge tables belonging to the same VLAN (same E-Tree instance) be
are made, duplication of MAC addresses would be needed for both made. Unless two lookups are made, duplication of MAC addresses
locally learned and remotely learned MAC addresses. Locally learned would be needed for both locally learned and remotely learned MAC
MAC addresses from Leaf ACs need to be duplicated onto Root bridge addresses. Locally learned MAC addresses from Leaf ACs need to be
table and locally learned MAC addresses from Root ACs need to be duplicated onto a Root bridge table, and locally learned MAC
duplicated onto Leaf bridge table. Remotely learned MAC addresses addresses from Root ACs need to be duplicated onto a Leaf bridge
from Root ACs need to be copied onto both Root and Leaf bridge table. Remotely learned MAC addresses from Root ACs need to be
tables. Because of potential inefficiencies associated with data- copied onto both Root and Leaf bridge tables. Because of potential
plane implementation of additional MAC lookup or duplication of MAC inefficiencies associated with data-plane implementation of
entries, this option is not believed to be implementable without additional MAC lookup or duplication of MAC entries, this option is
dataplane performance inefficiencies in some platforms and thus this not believed to be implementable without data-plane performance
document introduces the coloring as described in section 2.2 and inefficiencies in some platforms; thus, this document introduces the
detailed in section 3.1. coloring as described in Section 3.2 and detailed in Section 4.1.
Acknowledgements
We would like to thank Eric Rosen, Jeffrey Zhang, Wen Lin, Aldrin
Issac, Wim Henderickx, Dennis Cai, and Antoni Przygienda for their
valuable comments and contributions. The authors would also like to
thank Thomas Morin for shepherding this document and providing
valuable comments.
Authors' Addresses Authors' Addresses
Ali Sajassi Ali Sajassi (editor)
Cisco Cisco
Email: sajassi@cisco.com Email: sajassi@cisco.com
Samer Salam Samer Salam
Cisco Cisco
Email: ssalam@cisco.com Email: ssalam@cisco.com
John Drake John Drake
Juniper Juniper
Email: jdrake@juniper.net Email: jdrake@juniper.net
Jim Uttaro Jim Uttaro
AT&T AT&T
Email: ju1738@att.com Email: ju1738@att.com
Sami Boutros Sami Boutros
VMware VMware
Email: sboutros@vmware.com Email: sboutros@vmware.com
Jorge Rabadan Jorge Rabadan
Nokia Nokia
Email: jorge.rabadan@nokia.com Email: jorge.rabadan@nokia.com
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