L2VPN Workgroup Ali Sajassi
INTERNET-DRAFT Samer Salam
Intended Status: Standards Track Sami Boutros
Cisco
Wim Henderickx
Jorge Rabadan Jim Uttaro
Alcatel-Lucent AT&T
John Drake Aldrin Isaac
Wen Lin Bloomberg
Juniper
Expires: December 18, 2015 June 18, 2015
E-TREE Support in EVPN & PBB-EVPN
draft-ietf-bess-evpn-etree-01
Abstract
The Metro Ethernet Forum (MEF) has defined a rooted-multipoint
Ethernet service known as Ethernet Tree (E-Tree). [ETREE-FMWK]
proposes a solution framework for supporting this service in MPLS
networks. This document discusses how those functional requirements
can be easily met with (PBB-)EVPN and how (PBB-)EVPN offers a more
efficient implementation of these functions.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
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Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as
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and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html
The list of Internet-Draft Shadow Directories can be accessed at
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http://www.ietf.org/shadow.html
Copyright and License Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
2 E-Tree Scenarios and EVPN / PBB-EVPN Support . . . . . . . . . 4
2.1 Scenario 1: Leaf OR Root site(s) per PE . . . . . . . . . . 4
2.2 Scenario 2: Leaf AND Root site(s) per PE . . . . . . . . . . 5
2.3 Scenario 3: Leaf AND Root site(s) per Ethernet Segment . . . 5
3 Operation for EVPN . . . . . . . . . . . . . . . . . . . . . . . 6
3.1 Known Unicast Traffic . . . . . . . . . . . . . . . . . . . 7
3.2 BUM Traffic . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2.1 BUM Traffic supported by P2MP Tunnels . . . . . . . . . 7
3.2.1 BUM Traffic supported by Ingress Replication . . . . . . 9
3.3 E-TREE Traffic Flows for EVPN . . . . . . . . . . . . . . . 10
3.3.1 E-Tree with MAC Learning . . . . . . . . . . . . . . . . 11
3.3.2 E-Tree without MAC Learning . . . . . . . . . . . . . . 11
4 Operation for PBB-EVPN . . . . . . . . . . . . . . . . . . . . . 12
4.1 Known Unicast Traffic . . . . . . . . . . . . . . . . . . . 12
4.2 BUM Traffic . . . . . . . . . . . . . . . . . . . . . . . . 13
5 BGP Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.1 E-TREE Extended Community . . . . . . . . . . . . . . . . . 13
6 Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . 14
7 Security Considerations . . . . . . . . . . . . . . . . . . . . 14
8 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 14
9 References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
9.1 Normative References . . . . . . . . . . . . . . . . . . . 14
9.2 Informative References . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15
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1 Introduction
The Metro Ethernet Forum (MEF) has defined a rooted-multipoint
Ethernet service known as Ethernet Tree (E-Tree). In an E-Tree
service, endpoints are labeled as either Root or Leaf sites. Root
sites can communicate with all other sites. Leaf sites can
communicate with Root sites but not with other Leaf sites.
[ETREE-FMWK] proposes the solution framework for supporting E-Tree
service in MPLS networks. The document identifies the functional
components of the overall solution to emulate E-Tree services in
addition to Ethernet LAN (E-LAN) services on an existing MPLS
network.
[EVPN] is a solution for multipoint L2VPN services, with advanced
multi-homing capabilities, using BGP for distributing customer/client
MAC address reach-ability information over the MPLS/IP network. [PBB-
EVPN] combines the functionality of EVPN with [802.1ah] Provider
Backbone Bridging for MAC address scalability.
This document discusses how the functional requirements for E-Tree
service can be easily met with (PBB-)EVPN and how (PBB-)EVPN offers a
more efficient implementation of these functions.
1.1 Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [KEYWORDS].
2 E-Tree Scenarios and EVPN / PBB-EVPN Support
In this section, we will categorize support for E-Tree into three
different scenarios, depending on the nature of the site association
(Root/Leaf) per PE or per Ethernet Segment:
- Leaf OR Root site(s) per PE
- Leaf AND Root site(s) per PE
- Leaf AND Root site(s) per Ethernet Segment
2.1 Scenario 1: Leaf OR Root site(s) per PE
In this scenario, a PE may have Root sites OR Leaf sites for a given
VPN instance, but not both concurrently. The PE may have both Root
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and Leaf sites albeit for different VPNs. Every Ethernet Segment
connected to the PE is uniquely identified as either a Root or a Leaf
site.
+---------+ +---------+
| PE1 | | PE2 |
+---+ | +---+ | +------+ | +---+ | +---+
|CE1+-----ES1----+--+ | | | MPLS | | | +--+----ES2-----+CE2|
+---+ (Root) | | E | | | /IP | | | E | | (Leaf) +---+
| | V | | | | | | V | |
| | I | | | | | | I | | +---+
| | | | | | | | +--+----ES3-----+CE3|
| +---+ | +------+ | +---+ | (Leaf) +---+
+---------+ +---------+
Figure 1: Scenario 1
2.2 Scenario 2: Leaf AND Root site(s) per PE
In this scenario, a PE may have a set of one or more Root sites AND a
set of one or more Leaf sites for a given VPN instance. Every
Ethernet Segment connected to the PE is uniquely identified as either
a Root or a Leaf site.
+---------+ +---------+
| PE1 | | PE2 |
+---+ | +---+ | +------+ | +---+ | +---+
|CE1+-----ES1----+--+ | | | | | | +--+----ES2-----+CE2|
+---+ (Leaf) | | E | | | MPLS | | | E | | (Leaf) +---+
| | V | | | /IP | | | V | |
| | I | | | | | | I | | +---+
| | | | | | | | +--+----ES3-----+CE3|
| +---+ | +------+ | +---+ | (Root) +---+
+---------+ +---------+
Figure 2: Scenario 2
2.3 Scenario 3: Leaf AND Root site(s) per Ethernet Segment
In this scenario, a PE may have a set of one or more Root sites AND a
set of one or more Leaf sites for a given VPN instance. An Ethernet
Segment connected to the PE may be identified as both a Root and a
Leaf site concurrently.
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+---------+ +---------+
| PE1 | | PE2 |
+---+ | +---+ | +------+ | +---+ | +---+
|CE1+-----ES1----+--+ | | | | | | +--+----ES2-----+CE2|
+---+ (Leaf/Root)| | E | | | MPLS | | | E | | (Leaf/Root)+---+
| | V | | | /IP | | | V | |
| | I | | | | | | I | | +---+
| | | | | | | | +--+----ES3-----+CE3|
| +---+ | +------+ | +---+ | (Leaf) +---+
+---------+ +---------+
Figure 3: Scenario 3
3 Operation for EVPN
[EVPN] defines the notion of an Ethernet Segment which can be readily
used to identify a Root and/or Leaf site in E-TREE services. In other
words, [EVPN] has inherent capability to support E-TREE services
without defining any new BGP routes. It only requires a minor
modification to the existing procedures and a new BGP Extended
Community for leaf indication as shown later in this document.
In addition to the procedures below (which is a MUST requirement), an
EVPN PE implementation MAY provide topology constraint among the PEs
belonging to the same EVI associated with an E-TREE service. The
purpose of this topology constraint is to avoid having PEs with only
Leaf sites (e.g., scenario 1 in section 2.1) importing and processing
BGP MAC routes from each other, thereby unnecessarily exhausting
their RIB tables. However, when a Root site is added to a Leaf PE
(e.g., scenario 2 and 3 in sections 2.2 and 2.3), then that PE needs
to process MAC routes from all other Leaf PEs and add them to its
forwarding table. To support such topology constrain in EVPN, two BGP
Route-Targets (RTs) are used for every EVPN Instance (EVI): one RT is
associated with the Root sites and the other is associated with the
Leaf sites. On a per EVI basis, every PE exports the single RT
associated with its type of site(s). Furthermore, a PE with Root
site(s) imports both Root and Leaf RTs, whereas a PE with Leaf
site(s) only imports the Root RT. If for a given EVI, the PEs can
eventually have both Leaf and Root sites attached, even though they
may start as Root-only or Leaf-only PEs, then it is recommended to
use a single RT per EVI and avoid additional configuration and
operational overhead. If the number of EVIs is very large (e.g., more
than 32K or 64K), then RT type 0 as defined in [RFC4360] SHOULD be
used; otherwise, RT type 2 is sufficient.
The following procedures are used consistently for all the scenarios
highlighted in the previous section.
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3.1 Known Unicast Traffic
For known unicast traffic, the PE must advertise a Leaf indication
along with each MAC Advertisement route, to indicate that the
associated MAC address was learnt from a Leaf Attachment Circuit
(AC). The lack of a Leaf indication, indicates the MAC address is
learnt from a root AC. In other words, the default mode of operation
in an EVPN is that all ACs are root (can transmit and receive traffic
to/from other ACs in an EVI) unless the AC is explicitly identified
as a leaf.
Tagging MAC addresses with a leaf indication when they are associated
with a leaf AC, enables remote PEs to perform ingress filtering for
known unicast traffic - i.e., on the ingress PE, the MAC destination
address lookup yields, in addition to the forwarding adjacency, a
flag which indicates whether the target 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 are Leafs, then the packet is not
forwarded.
The PE places all Leaf ACs of a given bridge domain in a single
split-horizon group in order to prevent intra-PE forwarding among
Leaf ACs. This split-horizon function applies to both known unicast
and BUM traffic.
To support the above ingress filtering functionality, a new E-TREE
Extended Community with a Leaf indication flag is introduced [section
5.1]. This new Extended Community is advertised with each EVPN MAC/IP
Advertisement route.
3.2 BUM Traffic
For BUM traffic, it is not possible to perform filtering on the
ingress PE, as is the case with known unicast, because of the multi-
destination nature of the traffic. As such, the solution relies on
egress filtering. In order to apply the proper egress filtering,
which varies based on whether a packet is sent from a Root or a Leaf
AC, the MPLS-encapsulated frames MUST be tagged with an indication of
whether they originated from a Root or a Leaf AC. This can be
achieved in EVPN through the use of the ESI MPLS label. Therefore,
the ESI MPLS label not only identifies the Ethernet segment of origin
for a given frame, but also it identifies its type (e.g., Leaf or
Root).
3.2.1 BUM Traffic supported by P2MP Tunnels
For multi-homing use cases where BUM traffic uses P2MP LSP, the
ingress PE adds an upstream-assigned ESI MPLS label to the frame per
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[RFC7432] procedures and sends it to all the intended ingress PE
devices. Two ESI MPLS labels are used for each multi-homed Ethernet
segment that has both Root and Leaf sites: one ESI MPLS label that
only identifies the Ethernet segment of origin per [RFC7432] and
another one that not only identifies the Ethernet segment of origin
but also its type (which is Leaf). If an Ethernet segment has only
Root sites, then the former ESI MPLS label is used and if an Ethernet
segment has only Leaf sites, then the latter ESI MPLS label is used.
It should be noted that the former ESI MPLS label implicitly
identifies a Root Ethernet segment - i.e., an ESI MPLS label that is
signaled without the new E-TREE Extended Community (defined in
section [5.1]), is assumed to be of type Root. When advertising the
ESI MPLS label for an Ethernet Segment that has Leaf sites, the PE
MUST indicate that the corresponding ESI is of type Leaf. This is
achieved by advertising the Ethernet A-D per ES route with with the
ESI MPLS label Extended Community along with the new E-TREE Extended
Community that has a Leaf indication flag.
The egress PE can determine whether or not to forward a particular
frame to the destination Ethernet Segment depending on the following
rules:
- If the ESI MPLS label indicates that the source Ethernet Segment is
the same as destination Ethernet segment, then the frame is blocked
according to the split-horizon rule in [RFC7432].
- If the ESI MPLS label indicates that the source Ethernet Segment is
not the same as destination Ethernet segment and it doesn't have any
Leaf indication, then the frame is forwarded to the destination AC
according to the split-horizon rule in [RFC7432].
- If the ESI MPLS label indicates that the source Ethernet Segment is
not the same as destination Ethernet segment but it has a Leaf
indication, then the frame is blocked if the destination AC is of
type Leaf and it is forwarded if the destination AC is of type Root.
The ingress PE imposes the right ESI MPLS label depending on whether
the Ethernet frame originated from the Root or Leaf site on that
Ethernet Segment. The mechanism by which the PE identifies whether a
given frame originated from a Root or Leaf site on the segment is
based on the Ethernet Tag associated with the frame (e.g., whether
the frame come from a leaf or a root AC). Other mechanisms of
identification, beyond the Ethernet Tag, are outside the scope of
this document. It should be noted that support for both Root and Leaf
sites on a single Ethernet Segment requires that the PE performs the
Ethernet Segment split-horizon check on a per Ethernet Tag basis. In
the case where a multi-homed Ethernet Segment has only either Root or
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Leaf sites attached, then a single ESI MPL label is allocated and
advertised.
For single-homing use cases where BUM traffic uses P2MP LSP, the
ingress PE adds a special ESI MPLS label to the frame if the frame is
originated from a Leaf site. This special ESI MPLS label used for
single-homing scenarios is not on a per ES basis but rather on a per
PE basis - i.e., a single ESI MPLS label is used for all single-homed
segments on that PE. If the frame is originated from a Root site,
then the ingress PE does not add any ESI MPLS label per [RFC7432]
procedures. The egress PE, when receiving this special ESI MPLS
label, it blocks the frame if the destination AC is of type Leaf and
it forwards the frame if the destination AC is of type Root.
When a PE wants to advertise this special ESI label to other PE
devices, it advertises it using ESI MPLS label Extended Community
with the Ethernet A-D per ES route. The ESI for the Ethernet A-D per
ES route, can be of type 3, 4, or 5.
3.2.1 BUM Traffic supported by Ingress Replication
The procedures for supporting BUM traffic using ingress replication,
are similar to the ones in the previous section. The main differences
are that the ESI label is downstream assigned and not all egress PE
devices need to receive the ESI label just like ingress replication
procedures defined in [RFC7432].
For frames received from a multi-homed Ethernet segment, the ingress
PE may or may not add an ESI MPLS label based on the following
criteria:
- If the frame is forwarded to a PE that participates in the same
multi-homed Ethernet Segment and the frame is received on a Root AC,
then the ingress PE adds a per-ES downstream-assigned ESI MPLS label
to the frame per [RFC7432].
- If the frame is forwarded to a PE that participates in the same
multi-homed Ethernet Segment and the frame is received on a Leaf AC,
then the ingress PE adds the a per-ES downstream-assigned ESI MPLS
label indicating Leaf to the frame.
- If the frame is forwarded to a PE that does not participate in the
same multi-homed Ethernet Segment and the frame is received on a Leaf
AC, then the ingress PE adds a per-PE downstream-assigned special ESI
MPLS label indicating Leaf to the frame. This special ESI MPLS label
is per PE.
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- If the frame is forwarded to a PE that does not participate in the
same multi-homed Ethernet Segment and the frame is received on a Root
AC, then the ingress PE does not add any ESI MPLS label to the frame
per [RFC7432].
For frames received from a single-homed Ethernet segment, the ingress
PE may or may not add an ESI MPLS label based on the following
criteria:
- If the frame is received on a Root AC, then the ingress PE does not
add any ESI MPLS label to the frame.
- If the frame is received on a Leaf AC, then the ingress PE adds a
special downstream-assigned ESI MPLS label indicating Leaf to the
frame.
Just as described in the previous section, the Leaf indication is
signaled using the new E-TREE extended community defined in section
[5.1] along with the ESI MPLS label extended community with the
Ethernet A-D per ES route.
The egress PE can determine whether or not to forward a particular
frame to the desitnation Ethernet Segment depending on the following
rules:
- If the ESI MPLS label indicates that the source Ethernet Segment is
the same as destination Ethernet segment, then the frame is blocked
according to the split-horizon rule in [RFC7432].
- If the ESI MPLS label indicates that the source Ethernet Segment is
not the same as destination Ethernet segment and it doesn't have any
Leaf indication, then the frame is forwarded to the destination AC
according to the split-horizon rule in [RFC7432].
- If the ESI MPLS label indicates that the source Ethernet Segment is
not the same as destination Ethernet segment but it has a Leaf
indication, then the frame is blocked if the destination AC is of
type Leaf and it is forwarded if the destination AC is of type Root.
- If the ESI label is a special ESI MPLS label, then the frame is
blocked if the destination AC is of type Leaf and it is forwarded if
the destination AC is of type Root.
3.3 E-TREE Traffic Flows for EVPN
Per [ETREE-FMWK], a generic E-Tree service supports all of the
following traffic flows:
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- Ethernet Unicast from Root to Roots & Leaf
- Ethernet Unicast from Leaf to Root
- Ethernet Broadcast/Multicast from Root to Roots & Leafs
- Ethernet Broadcast/Multicast from Leaf to Roots
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
application. In the case where unicast flows need not be supported,
the L2VPN PEs can avoid performing any MAC learning function.
In the subsections that follow, we will describe the operation of
EVPN to support E-Tree service with and without MAC learning.
3.3.1 E-Tree with MAC Learning
The PEs implementing an E-Tree service must perform MAC learning when
unicast traffic flows must be supported from Root to Leaf or from
Leaf to Root sites. In this case, the PE with Root sites performs MAC
learning in the data-path over the Ethernet Segments, and advertises
reachability in EVPN MAC Advertisement routes. These routes will be
imported by PEs that have Leaf sites as well as by PEs that have Root
sites, in a given EVI. Similarly, the PEs with Leaf sites perform MAC
learning in the data-path over their Ethernet Segments, and advertise
reachability in EVPN MAC Advertisement routes which are imported only
by PEs with at least one Root site in the EVI. A 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 the case of multi-
homed segments) and for mass MAC withdrawal.
To support multicast/broadcast from Root to Leaf sites, either a P2MP
tree rooted at the PE(s) with the Root site(s) or ingress replication
can be used. The multicast tunnels are set up through the exchange of
the EVPN Inclusive Multicast route, as defined in [RFC7432].
To support multicast/broadcast from Leaf to Root sites, ingress
replication should be sufficient for most scenarios where there is a
single Root or few Roots. If the number of Roots is large, a P2MP
tree rooted at the PEs with Leaf sites may be used.
3.3.2 E-Tree without MAC Learning
The PEs implementing an E-Tree service need not perform MAC learning
when the traffic flows between Root and Leaf sites are multicast or
broadcast. In this case, the PEs do not exchange EVPN MAC
Advertisement routes. Instead, the Ethernet A-D routes are used to
exchange the EVPN labels.
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The fields of the Ethernet A-D route are populated per the procedures
defined in [RFC7432], and the route import rules are as described in
previous sections.
4 Operation for PBB-EVPN
In PBB-EVPN, the PE must advertise a Root/Leaf indication along with
each MAC Advertisement route, to indicate whether the associated B-
MAC address corresponds to a Root or a Leaf site. Similar to the EVPN
case, this flag will be added to the new E-TREE extended community
defined in section [5.1], and advertised with each MAC Advertisement
route.
In the case where a multi-homed Ethernet Segment has both Root and
Leaf sites attached, two B-MAC addresses are allocated and
advertised: one B-MAC address implicitly denoting Root and the other
explicitly denoting Leaf. The former B-MAC address is not advertised
with the E-TREE extended community but the latter B-MAC denoting Leaf
is advertised with the new E-TREE extended community.
The ingress PE uses the right B-MAC source address depending on
whether the Ethernet frame originated from the Root or Leaf site on
that Ethernet Segment. The mechanism by which the PE identifies
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
mechanisms of identification, beyond the Ethernet Tag, are outside
the scope of this document. It should be noted that support for both
Root and Leaf sites on a single Ethernet Segment requires that the PE
performs the Ethernet Segment split-horizon check on a per Ethernet
Tag basis.
In the case where a multi-homed Ethernet Segment has only Root or
Leaf sites attached, then a single B-MAC address is allocated and
advertised per segment.
Furthermore, a PE advertises two special global B-MAC addresses: one
for Root and another for Leaf, and tags them as such in the MAC
Advertisement routes. These B-MAC addresses are used as source
addresses for traffic originating from single-homed segments.
4.1 Known Unicast Traffic
For known unicast traffic, the PEs perform ingress filtering: On the
ingress PE, the C-MAC destination address lookup yields, in addition
to the target B-MAC address and forwarding adjacency, a flag which
indicates whether the target B-MAC is associated with a Root or a
Leaf site. The ingress PE cross-checks this flag with the status of
the originating site, and if both are a Leaf, then the packet is not
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forwarded.
The PE places all Leaf Ethernet Segments of a given bridge domain in
a single split-horizon group in order to prevent intra-PE forwarding
among Leaf segments. This split-horizon function applies to BUM
traffic as well.
4.2 BUM Traffic
For BUM traffic, the PEs must perform egress filtering. When a PE
receives a MAC advertisement route, it updates its Ethernet Segment
egress filtering function (based on the B-MAC source address), as
follows:
- If the MAC 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 the B-MAC filtering list.
- Otherwise, the B-MAC filtering list is not updated.
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
that this uses the same filtering logic as baseline [PBB-EVPN] and
does not require any additional flags in the data-plane.
5 BGP Encoding
This document defines one new BGP Extended Community for EVPN.
5.1 E-TREE Extended Community
A new EVPN BGP Extended Community called E-TREE is introduced here.
This new extended community is a transitive extended community with
the Type field of 0x06 (EVPN) and the Sub-Type of 0x04. This extended
community is used to for leaf indication and it is advertised with an
EVPN MAC/IP route or an Ethernet A-D per ES route. When advertised
with an Ethernet A-D per ES route, it is sent along with ESI Label
Extended Community defined in section 7.5 of [RFC7432].
The E-TREE Extended Community is encoded as an 8-octet value as
follows:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=0x06 | Sub-Type=0x04 | E-TREE Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| E-TREE Flags L|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Leaf flag (L): A value of 1 indicates a leaf
6 Acknowledgement
We would like to thank Dennis Cai for his comments.
7 Security Considerations
Same security considerations as [RFC7432].
8 IANA Considerations
Allocation of Extended Community Type and Sub-Type for EVPN.
9 References
9.1 Normative References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4360] S. Sangli et al, ""BGP Extended Communities Attribute",
February, 2006.
[RFC7432] Sajassi et al., "BGP MPLS Based Ethernet VPN", February,
2015.
9.2 Informative References
[ETREE-FMWK] Key et al., "A Framework for E-Tree Service over MPLS
Network", draft-ietf-l2vpn-etree-frwk-03, work in progress, September
2013.
[PBB-EVPN] Sajassi et al., "PBB-EVPN", draft-ietf-l2vpn-pbb-evpn-
05.txt, work in progress, October, 2013.
Sajassi et al. Expires December 18, 2015 [Page 14]
INTERNET DRAFT E-TREE Support in EVPN & PBB-EVPN June 18, 2015
Authors' Addresses
Ali Sajassi
Cisco
Email: sajassi@cisco.com
Samer Salam
Cisco
Email: ssalam@cisco.com
Wim Henderickx
Alcatel-Lucent
Email: wim.henderickx@alcatel-lucent.com
Jim Uttaro
AT&T
Email: ju1738@att.com
Aldrin
Bloomberg Issac
Email: aisaac71@bloomberg.net
Sami Boutros
Cisco
Email: sboutros@cisco.com
Sajassi et al. Expires December 18, 2015 [Page 15]