wdiff rfc8214.alt-original rfc8214.txt

INTERNET-DRAFT Sami
Internet Engineering Task Force (IETF) S. Boutros
Intended Status: Standard Track
Request for Comments: 8214 VMware
Ali
Category: Standards Track A. Sajassi
Samer
ISSN: 2070-1721 S. Salam
Cisco Systems
John
J. Drake
Juniper Networks
J. Rabadan
Nokia

Expires: November 15, 2017 May 14,
August 2017

Virtual Private Wire Service support Support in Ethernet VPN
draft-ietf-bess-evpn-vpws-14.txt

Abstract

This document describes how Ethernet VPN (EVPN) can be used to
support the Virtual Private Wire Service (VPWS) in MPLS/IP networks.
EVPN
enables accomplishes the following characteristics for VPWS: single-active provides Single-Active as
well as all-active multi-homing All-Active multihoming with flow-based load-balancing,
eliminates the need for Pseudowire (PW) signaling, and provides fast
protection convergence upon node or link failure.

Status of this This Memo

This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as
Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum
(IETF). It represents the consensus of six months the IETF community. It has
received public review and may be updated, replaced, or obsoleted has been approved for publication by other documents at any
time. It the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work available in progress."

The list Section 2 of RFC 7841.

Information about the current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html

The list status of Internet-Draft Shadow Directories can this document, any errata,
and how to provide feedback on it may be accessed obtained at
http://www.ietf.org/shadow.html
https://www.rfc-editor.org/info/rfc8214.

This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info)
(https://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 . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 ....................................................3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
2 ................................................5
2. Service interface . . . . . . . . . . . . . . . . . . . . . . . 6
2.1 Interface ...............................................6
2.1. VLAN-Based Service Interface . . . . . . . . . . . . . . . . 6
2.2 ...............................6
2.2. VLAN Bundle Service Interface . . . . . . . . . . . . . . . 6
2.2.1 ..............................7
2.2.1. Port-Based Service Interface . . . . . . . . . . . . . . 7
2.3 ........................7
2.3. VLAN-Aware Bundle Service Interface . . . . . . . . . . . . 7 ........................7
3. BGP Extensions . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1 ..................................................7
3.1. EVPN Layer 2 attributes extended community . . . . . . . . . 7
4 Attributes Extended Community .................8
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5 ......................................................10
5. EVPN Comparison to PW Signaling . . . . . . . . . . . . . . . . 11
6 ................................11
6. Failure Scenarios . . . . . . . . . . . . . . . . . . . . . . . 11
6.1 ..............................................12
6.1. Single-Homed CEs . . . . . . . . . . . . . . . . . . . . . . 11
6.2 Multi-Homed ..........................................12
6.2. Multihomed CEs . . . . . . . . . . . . . . . . . . . . . . 12
7 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 12
8 ............................................12
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 12
9 ........................................13
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 12
10 ............................................13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
10.1 .....................................................13
9.1. Normative References . . . . . . . . . . . . . . . . . . . 13
10.2 ......................................13
9.2. Informative References . . . . . . . . . . . . . . . . . . 13 ....................................14
Acknowledgements ..................................................16
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 ......................................................16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14

1 ................................................17

1. Introduction

This document describes how EVPN can be used to support VPWS in
MPLS/IP networks. The use of EVPN mechanisms for VPWS (EVPN-VPWS)
brings the benefits of EVPN to Point to Point Point-to-Point (P2P) services. These
benefits include single-active Single-Active redundancy as well as all-active All-Active
redundancy with flow-based load-balancing. Furthermore, the use of
EVPN for VPWS eliminates the need for the traditional way of PW
signaling for P2P Ethernet services, as described in section Section 4.

[RFC7432] provides the ability to forward customer traffic to/from a
given customer Attachment Circuit (AC), without any Media Access
Control (MAC) lookup. This capability is ideal in providing P2P
services (aka VPWS services). [MEF] defines the Ethernet Virtual
Private Line (EVPL) service as a P2P service between a pair of ACs
(designated by VLANs) and the Ethernet Private Line (EPL) service,
in which all traffic flows are between a single pair of ports, that ports that,
in EVPN
terminology terminology, would mean a single pair of Ethernet Segments
ES(es). EVPL can be considered as a VPWS with only two ACs. In
delivering an EVPL service, the traffic forwarding traffic-forwarding capability of EVPN
is based on the exchange of a pair of Ethernet Auto-discovery Auto-Discovery (A-D) routes;
whereas,
routes, whereas for more general VPWS as per [RFC4664], traffic forwarding the
traffic-forwarding capability of EVPN is based on the exchange of a
group of Ethernet AD A-D routes (one Ethernet AD A-D route per AC/ES). In
a VPWS service, the traffic from an originating Ethernet Segment can
be forwarded only to a single destination Ethernet Segment; hence, no
MAC lookup is needed needed, and the MPLS label associated with the per EVPN per-EVPN
instance (EVI) Ethernet A-D route can be used in forwarding user
traffic to the destination AC.

For both EPL and EVPL services, a specific VPWS service instance is
identified by a pair of per-EVI Ethernet A-D routes which that together
identify the VPWS service instance endpoints and the VPWS service
instance. In the control plane plane, the VPWS service instance is
identified using the VPWS service instance identifiers advertised by
each Provider Edge node (PE). (PE) node. In the data plane plane, the value of the
MPLS label advertised by one PE is used by the other PE to send
traffic for that VPWS service instance. As with the Ethernet Tag in
standard EVPN, the VPWS service instance identifier has uniqueness
within an EVPN instance.

For EVPN routes, the Ethernet Tag IDs are set to zero for Port-based, port-based,
VLAN-based, and VLAN-bundle VLAN bundle interface mode and set to non-zero
Ethernet Tag IDs for VLAN-aware bundle mode. Conversely, for EVPN-
VPWS,
EVPN-VPWS, the Ethernet Tag ID in the Ethernet A-D route MUST be set
to a non-zero value for all four service interface types.

In terms of route advertisement and MPLS label lookup behavior, EVPN-
VPWS
EVPN-VPWS resembles the VLAN-aware bundle mode of [RFC7432] such that
when a PE advertises a per-EVI Ethernet A-D route, the VPWS service
instance serves as a 32-bit normalized Ethernet Tag ID. The value of
the MPLS label in this route represents both the EVI and the VPWS
service instance, so that upon receiving an MPLS encapsulated MPLS-encapsulated packet,
the disposition PE can identify the egress AC from the MPLS label and
subsequently perform any required tag translation. For the EVPL
service, the Ethernet frames transported over an MPLS/IP network
SHOULD remain tagged with the originating VLAN-ID (VID) VLAN ID (VID), and any VID
translation MUST be performed at the disposition PE. For the EPL
service, the Ethernet frames are transported as is is, and the tags
are not altered.

The MPLS label value in the Ethernet A-D route can be set to the
Virtual Extensible LAN (VXLAN) Network Identifier (VNI) for VXLAN
encapsulation as per [RFC7348], and this VNI will have a local scope
per PE and may also be equal to the VPWS service instance identifier
set in the Ethernet A-D route. When using VXLAN encap, encapsulation, the
BGP Encapsulation extended community is included in the Ethernet A-D
route as described in [ietf-evpn-overlay]. [EVPN-OVERLAY]. The VXLAN VNI is like the MPLS label
that will be set in the tunnel header used to tunnel Ethernet packets
from all the service interface types defined in
section Section 2. The
EVPN-VPWS techniques defined in this document has have no dependency on
the tunneling technology.

The Ethernet Segment identifier Identifier encoded in the Ethernet A-D per-EVI
route is not used to identify the service. However However, it can be used
for flow-based load-balancing and mass withdraw functions as per the
[RFC7432] baseline.

As with standard EVPN, the Ethernet A-D per-ES route is used for fast
convergence upon link or node failure. The Ethernet Segment route is
used for auto-discovery of the PEs attached to a given multi-homed multihomed
Customer Edge node (CE) and to synchronize state between them.

1.1

1.1. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.

EVPN: Ethernet VPN VPN.

MAC: Media Access Control Control.

MPLS: Multi Protocol Multiprotocol Label Switching.

OAM: Operations, Administration Administration, and Maintenance.

PE: Provide Provider Edge Node.

AS: Autonomous System.

ASBR: Autonomous System Border Router Router.

CE: Customer Edge device e.g., host or router (e.g., host, router, or switch. switch).

EVPL: Ethernet Virtual Private Line.

EPL: Ethernet Private Line.

EP-LAN: Ethernet Private LAN.

EVP-LAN: Ethernet Virtual Private LAN.

S-VLAN: Service VLAN identifier.

C-VLAN: Customer VLAN identifier.

VID: VLAN-ID. VLAN ID.

VPWS: Virtual Private Wire Service.

EVI: EVPN Instance.

P2P: Point to Point.

VXLAN: Virtual Extensible LAN.

DF: Designated Forwarder.

L2: Layer 2.

MTU: Maximum Transmission Unit.

eBGP: Exterior External Border Gateway Protocol.

iBGP: Internal Border Gateway Protocol.

ES: Ethernet Segment "Ethernet Segment" on a PE refers to the link attached to it, this it.
This link can be part of a set of links attached to different PEs
in multi
homed cases, multihomed cases or could be a single link in single homed single-homed
cases.

ESI: Ethernet Segment Identifier.

Single-Active Mode: When a device or a network is multi-homed multihomed to two
or more PEs and when only a single PE in such a redundancy group
can forward traffic to/from the multi-homed multihomed device or network for a
given VLAN, then such multi-homing multihoming or redundancy is referred to as "Single-
Active".

All-Active:
"Single-Active".

All-Active Mode: When a device is multi-homed multihomed to two or more PEs and
when all PEs in such a redundancy group can forward traffic
to/from the
multi-homed multihomed device for a given VLAN, then such multi-homing
multihoming or redundancy is referred to as "All-Active".

VPWS Service Instance: It A VPWS service instance is represented by a
pair of EVPN service labels associated with a pair of endpoints.
Each label is downstream
assigned downstream-assigned and advertised by the
disposition PE through an Ethernet A-D per-EVI route. The
downstream label identifies the endpoint on the disposition PE. A
VPWS service instance can be associated with only one VPWS service
identifier.

2. Service interface

2.1 Interface

2.1. VLAN-Based Service Interface

With this service interface, a VPWS instance identifier corresponds
to only a single VLAN on a specific interface. Therefore, there is a
one-to-one mapping between a VID on this interface and the VPWS
service instance identifier. The PE provides the cross-connect
functionality between an MPLS LSP Label Switched Path (LSP) identified by
the VPWS service instance identifier and a specific <port,VLAN>. <port, VLAN>. If
the VLAN is represented by different VIDs on different PEs and
different ES(es), ES(es) (e.g., a different VID per Ethernet segment Segment per PE),
then each PE needs to perform VID translation for frames destined to
its Ethernet
segment. Segment. In such scenarios, the Ethernet frames
transported over an MPLS/IP network SHOULD remain tagged with the
originating VID, and a VID translation MUST be supported in the data
path and MUST be performed on the disposition PE.

2.2

2.2. VLAN Bundle Service Interface

With this service interface, a VPWS service instance identifier
corresponds to multiple VLANs on a specific interface. The PE
provides the cross-connect functionality between the MPLS label
identified by the VPWS service instance identifier and a group of
VLANs on a specific interface. For this service interface, each VLAN
is presented by a single VID VID, which means that no VLAN translation is
allowed. The receiving PE, PE can direct the traffic traffic, based on the EVPN
label
alone alone, to a specific port. The transmitting PE can
cross-connect traffic from a group of VLANs on a specific port to the
MPLS label. The MPLS-encapsulated frames MUST remain tagged with the
originating VID.

2.2.1

2.2.1. Port-Based Service Interface

This service interface is a special case of the VLAN bundle service
interface, where all of the VLANs on the port are mapped to the same
VPWS service instance identifier. The procedures are identical to
those described in Section 2.2.

2.3

2.3. VLAN-Aware Bundle Service Interface

Contrary to EVPN, in EVPN-VPWS this service interface maps to a VLAN-
based
VLAN-based service interface (defined in section 2.1) and thus Section 2.1); thus, this
service interface is not used in EVPN-VPWS. In other words, if one
tries to define data plane data-plane and control plane control-plane behavior for this
service interface, one would realize that it is the same as that of
the VLAN-based service.

3. BGP Extensions

This document specifies the use of the per-EVI Ethernet A-D route to
signal VPWS services. The Ethernet Segment Identifier ESI field is set to the customer ES ES, and
the 32-bit Ethernet Tag ID 32-bit field MUST be set to the VPWS service
instance identifier value. The VPWS service instance identifier
value MAY be set to a 24-bit value value, and when a 24-bit value is used,
it MUST be right aligned. right-aligned. For both EPL and EVPL services using a
given VPWS service instance, the pair of PEs instantiating that VPWS
service instance will each advertise a per-EVI Ethernet A-D route
with its VPWS service instance identifier and will each be configured
with the other PE's VPWS service instance identifier. When each PE
has received the other PE's per-EVI Ethernet A-D route, the VPWS
service instance is instantiated. It should be noted that the same
VPWS service instance identifier may be configured on both PEs.

The Route-Target Route Target (RT) extended community with which the per-EVI
Ethernet A-D route is tagged identifies the EVPN instance in which
the VPWS service instance is configured. It is the operator's choice
as to how many and which VPWS service instances are configured in a
given EVPN instance. However, a given EVPN instance MUST NOT be
configured with both VPWS service instances and standard EVPN multi-
point
multipoint services.

3.1

3.1. EVPN Layer 2 attributes extended community Attributes Extended Community

This document defines a new extended community [RFC4360], to be
included with per-EVI Ethernet A-D routes. This attribute is
mandatory if multihoming is enabled.

+------------------------------------+

+-------------------------------------------+
| Type(0x06)/Sub-type(0x04)(2 octet)|
+------------------------------------+ Type (0x06) / Sub-type (0x04) (2 octets) |
+-------------------------------------------+
| Control Flags (2 octets) |
+------------------------------------+
+-------------------------------------------+
| L2 MTU (2 octets) |
+------------------------------------+
+-------------------------------------------+
| Reserved (2 octets) |
+------------------------------------+
+-------------------------------------------+

Figure 1: EVPN Layer 2 attributes extended community Attributes Extended Community

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ |C|P|B| (MBZ = MUST Be Zero)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 2: EVPN Layer 2 attributes Attributes Control Flags
The following bits in the Control Flags are defined; the remaining
bits MUST be set to zero when sending and MUST be ignored when
receiving this community.

Name Meaning
---------------------------------------------------------------
P If set to 1 in multihoming single-active Single-Active scenarios, it
this flag indicates that the advertising PE is the Primary
primary PE. MUST be set to 1 for multihoming all-active
All-Active scenarios by all active PE(s).

B If set to 1 in multihoming single-active Single-Active scenarios, it
this flag indicates that the advertising PE is the Backup
backup PE.

C If set to 1, a Control control word [RFC4448] MUST be present
when sending EVPN packets to this PE. It is
recommended to
include that the control word be included in the
absence of Entropy Label. an entropy label [RFC6790].

L2 MTU (Maximum Transmission Unit) is a 2-octet value indicating the MTU in bytes.

A received L2 MTU of zero means that no MTU checking against the
local MTU is needed. A received non-zero MTU MUST be checked against
the local MTU MTU, and if there is a mismatch, the local PE MUST NOT add
the remote PE as the EVPN destination for the corresponding VPWS
service instance.

The usage of the Per ES per-ES Ethernet A-D route is unchanged from its
usage in [RFC7432], i.e., the "Single-Active" bit in the flags of the
ESI Label extended community will indicate if single-active or all-
active redundancy is used for this ES.

In multihoming scenarios, the B and P flags MUST be cleared. A PE
that receives an update with both B and P flags set MUST treat the
route as a withdrawal. If the PE receives a route with both B and P
clear, it MUST treat the route as a withdrawal from of the sender PE.
ESI Label extended community will indicate if Single-Active or
All-Active redundancy is used for this ES.

In a multihoming all-active All-Active scenario, there is no Designated
Forwarder (DF) election, and all the PEs in the ES that are active
and ready to forward traffic to/from the CE will set the P Flag. A
remote PE will do per-flow load-balancing to the PEs that set the
P Flag for the same Ethernet Tag and ESI. The B Flag in control flags
Control Flags SHOULD NOT be set in the multihoming all-active All-Active
scenario and MUST be ignored by receiving PE(s) if set.

In a multihoming single-active Single-Active scenario for a given VPWS service
instance, the DF election should result in the Primary-elected primary-elected PE for
the VPWS service instance advertising the P Flag set and the B Flag
clear, the Backup elected backup-elected PE should advertise the P Flag clear and
the B Flag set, and the rest of the PEs in the same ES should signal
both the P Flag and the B Flags Flag clear. When the primary PE/ES fails,
the primary PE will withdraw the associated Ethernet A-D routes for
the VPWS service instance from the remote PE PE, and the remote PEs PE
should then send traffic associated with the VPWS instance to the
backup PE. DF re-election will happen between the PE(s) in the same
ES, and there will be a newly elected primary PE and newly elected
backup PE that will signal the P and B Flags as described. A remote
PE SHOULD receive the P Flag set from only one Primary primary PE and the B
Flag set from only one Backup backup PE. However However, during transient
situations, a remote PE receiving a P Flag set from more than one PE
will select the last advertising PE as the primary PE when forwarding
traffic. A remote PE receiving a B Flag set from more than one PE
will select the last advertising PE as the backup PE. A remote PE
MUST receive a P Flag set from at least one PE before forwarding
traffic.

If a network uses entropy labels per [RFC6790] [RFC6790], then the C Flag
MUST NOT be set set, and the control word MUST NOT be used when sending EVPN-
encapsulated
EVPN-encapsulated packets over a P2P LSP.

4. Operation

The following figure shows an example of a P2P service deployed
with EVPN.

Ethernet Ethernet
Native |<--------- EVPN Instance ----------->| Native
Service | | Service
(AC) | |<-PSN1->| |<-PSN2->| | (AC)
| V V V V V V |
| +-----+ +-----+ +-----+ +-----+ |
+----+ | | PE1 |======|ASBR1|==|ASBR2|===| PE3 | | +----+
| |-------+-----+ +-----+ +-----+ +-----+-------| |
| CE1| | | |CE2 |
| |-------+-----+ +-----+ +-----+ +-----+-------| |
+----+ | | PE2 |======|ASBR3|==|ASBR4|===| PE4 | | +----+
^ +-----+ +-----+ +-----+ +-----+ ^
| Provider Edge 1 ^ Provider Edge 2 |
| | |
| | |
| EVPN Inter-provider point |
| |
|<---------------- Emulated Service -------------------->|

Figure 3: EVPN-VPWS Deployment Model

iBGP sessions are established between PE1, PE2, ASBR1 ASBR1, and ASBR3,
possibly via a BGP route-reflector. route reflector. Similarly, iBGP sessions are
established between among PE3, PE4, ASBR2 ASBR2, and ASBR4. eBGP sessions are
established among ASBR1, ASBR2, ASBR3, and ASBR4.

All PEs and ASBRs are enabled for the EVPN SAFI Subsequent Address Family
Identifier (SAFI) and exchange per-EVI Ethernet A-D routes, one route
per VPWS service instance. For inter-
AS inter-AS option B, the ASBRs
re-advertise these routes with the NEXT_HOP attribute set to their IP
addresses as per [RFC4271]. The link between the CE and the PE is
either a C-tagged or S-tagged interface, as described in [802.1Q],
that can carry a single VLAN tag or two nested VLAN tags tags, and it is
configured as a trunk with multiple VLANs, one per VPWS service
instance. It should be noted that the VLAN ID used by the customer
at either end of a VPWS service instance to identify that service
instance may be different different, and EVPN doesn't perform that translation
between the two values. Rather, the MPLS label will identify the
VPWS service instance instance, and if translation is needed, it should be
done by the Ethernet interface for each service.

For a single-homed CE, in an advertised per-EVI Ethernet A-D route route,
the ESI field is set to 0 zero and the Ethernet Tag ID is set to the
VPWS service instance identifier that identifies the EVPL or EPL
service.

For a multi-homed multihomed CE, in an advertised per-EVI Ethernet A-D route route, the
ESI field is set to the CE's ESI and the Ethernet Tag ID is set to
the VPWS service instance identifier, which MUST have the same value
on all PEs attached to that ES. This allows an ingress PE in a
multihoming all-active All-Active scenario to perform flow-based load-balancing
of traffic flows to all of the PEs attached to that ES. In all cases
cases, traffic follows the transport paths, which may be asymmetric.

The

Either (1) the VPWS service instance identifier encoded in the
Ethernet Tag ID in an advertised per-EVI Ethernet A-D route MUST either be
unique across all ASs, ASes or (2) an ASBR needs to perform a translation
when the per-EVI Ethernet A-D route is re-advertised by the ASBR from
one AS to the other AS.

A per-ES Ethernet A-D route can be used for mass withdraw to withdraw
all per-EVI Ethernet A-D routes associated with the multi-home multihomed site
on a given PE.

5. EVPN Comparison to PW Signaling

In EVPN, service endpoint discovery and label signaling are done
concurrently using BGP. Whereas, BGP, whereas with VPWS based on [RFC4448], label
signaling is done via LDP and service endpoint discovery is either
through manual provisioning or through BGP.

In existing implementations of VPWS using pseudowires(PWs), PWs, redundancy is limited
to single-active Single-Active mode, while with EVPN
implementation implementations of VPWS VPWS, both single-active
Single-Active and all-active All-Active redundancy modes can be supported.

In existing implementations with PWs, backup PWs are not used to
carry traffic, while with EVPN, traffic can be load-balanced among
different PEs multi-homed multihomed to a single CE.

Upon link or node failure, EVPN can trigger failover with the
withdrawal of a single BGP route per EVPL service or multiple EVPL
services, whereas with VPWS PW redundancy, the failover sequence
requires the exchange of two control plane control-plane messages: one message to
deactivate the group of primary PWs and a second message to activate
the group of backup PWs associated with the access link.

Finally, EVPN may employ data plane data-plane egress link protection mechanisms
not available in VPWS. This can be done by the primary PE (on local
AC down) using the label advertised in the per-EVI Ethernet A-D route
by the backup PE to encapsulate the traffic and direct it to the
backup PE.

6. Failure Scenarios

On a link or port failure between the CE and the PE for both single
single-homed and multi-homed multihomed CEs, unlike [RFC7432] [RFC7432], the PE MUST
withdraw all the associated Ethernet A-D routes for the VPWS service
instances on the failed port or link.

6.1

6.1. Single-Homed CEs

Unlike [RFC7432], EVPN-VPWS uses Ethernet A-D route advertisements
for single-homed Ethernet Segments. Therefore, upon a link/port
failure of this a given single-homed Ethernet Segment, the PE MUST
withdraw the associated per-EVI Ethernet A-D routes.

6.2 Multi-Homed

6.2. Multihomed CEs

For a faster convergence in multi-homed multihomed scenarios with either Single-
Active Redundancy
Single-Active redundancy or All-active All-Active redundancy, a mass withdraw
technique is used. A PE previously advertising a per-ES Ethernet A-D route,
route can withdraw this route by signaling to the remote PEs to
switch all the VPWS service instances associated with this multi-homed multihomed
ES to the backup PE.

Just like RFC 7432, the Ethernet A-D per-EVI route MUST NOT be used
for traffic forwarding by a remote PE until it also receives the
associated set of Ethernet A-D per-ES routes.

7. Security Considerations

The mechanisms in this document use the EVPN control plane as defined
in [RFC7432]. Security The security considerations described in [RFC7432] are
equally applicable.

This document uses MPLS and IP-based tunnel technologies to support
data plane
data-plane transport. Security The security considerations described in
[RFC7432] and in [ietf-evpn-overlay] [EVPN-OVERLAY] are equally applicable.

8. IANA Considerations

IANA has allocated the following EVPN Extended Community sub-type:
SUB-TYPE VALUE NAME

Sub-Type Value Name Reference
--------------------------------------------------------
0x04 EVPN Layer 2 Attributes [RFCXXXX] RFC 8214

This document creates a registry called "EVPN Layer 2 Attributes
Control Flags". New registrations will be made through the
"RFC Required" procedure defined in [RFC5226]. [RFC8126].

Initial registrations are as follows:

P Advertising PE is the Primary primary PE.
B Advertising PE is the Backup backup PE.
C Control word [RFC4448] MUST be present.

9. References

10.1

9.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>.
<https://www.rfc-editor.org/info/rfc2119>.

[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>.

[RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432,
February 2015, <http://www.rfc-
editor.org/info/rfc7432>. <https://www.rfc-editor.org/info/rfc7432>.

[RFC4448] Martini, L., Ed., Rosen, E., El-Aawar, N., and G. Heron,
"Encapsulation Methods for Transport of Ethernet over MPLS
Networks", RFC 4448, DOI 10.17487/RFC4448, April 2006. 2006,
<https://www.rfc-editor.org/info/rfc4448>.

[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and
L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
RFC 6790, DOI 10.17487/RFC6790, November 2012. 2012,
<https://www.rfc-editor.org/info/rfc6790>.

[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006, <http://www.rfc-
editor.org/info/rfc4271>.
<https://www.rfc-editor.org/info/rfc4271>.

[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
February 2006, <http://www.rfc-
editor.org/info/rfc4360>.

[RFC5226] Narten, T. <https://www.rfc-editor.org/info/rfc4360>.

[RFC8126] Cotton, M., Leiba, B., and H. Alvestrand, T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>. 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.

[RFC7348] Mahalingam, M., et al, "VXLAN: Dutt, D., Duda, K., Agarwal, P., Kreeger,
L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
eXtensible Local Area Network (VXLAN): A Framework for
Overlaying Virtualized Layer 2 Networks over Layer 3
Networks", RFC 7348, DOI 10.17487/RFC7348, August
2014

10.2 2014,
<https://www.rfc-editor.org/info/rfc7348>.

9.2. Informative References

[MEF] Metro Ethernet Forum, "Ethernet "EVC Ethernet Services Definitions -
Phase
2", 3", Technical Specification MEF 6.1, April 2008,
https://www.mef.net/Assets/Technical_Specifications/PDF/MEF_6.1.pdf 6.2, August 2014,
<https://www.mef.net/Assets/Technical_Specifications/
PDF/MEF_6.2.pdf>.

[RFC4664] Andersson, L., Ed., and E. Rosen, Ed., "Framework for
Layer 2 Virtual Private Networks (L2VPNs)", RFC 4664,
DOI 10.17487/RFC4664, September 2006,
<http://www.rfc-editor.org/info/rfc4664>.

[ietf-evpn-overlay] Sajassi-Drake et al.,
<https://www.rfc-editor.org/info/rfc4664>.

[EVPN-OVERLAY]
Sajassi, A., Ed., Drake, J., Ed., Bitar, N., Shekhar, R.,
Uttaro, J., and W. Henderickx, "A Network Virtualization
Overlay Solution using EVPN", draft-ietf-bess-evpn-overlay-07.txt,
work Work in progress, December, 2016

7 Progress,
draft-ietf-bess-evpn-overlay-08, March 2017.

[802.1Q] IEEE, "IEEE Standard for Local and metropolitan area
networks -- Media Access Control (MAC) Bridges and Virtual
Bridge Local Area Networks", IEEE Std 802.1Q-2011,
DOI 10.1109/IEEESTD.2011.6009146.

Acknowledgements

The authors would like to acknowledge Jeffrey Zhang, Wen Lin, Nitin
Singh, Senthil Sathappan, Vinod Prabhu, Himanshu Shah, Iftekhar
Hussain, Alvaro Retana Retana, and Acee Lindem for their feedback and
contributions to this document.

Contributors

In addition to the authors listed on the front page, the following
co-authors
coauthors have also contributed to this document:

Jeff Tantsura
Individual
Email: jefftant@gmail.com

Dirk Steinberg
Steinberg Consulting
Email: dws@steinbergnet.net

Patrice Brissette
Cisco Systems
Email: pbrisset@cisco.com

Thomas Beckhaus
Deutsche Telecom
Email: Thomas.Beckhaus@telekom.de

Ryan Bickhart
Juniper Networks
Email: rbickhart@juniper.net

Daniel Voyer
Bell Canada

Authors' Addresses

Sami Boutros
VMware, Inc.

Email: sboutros@vmware.com

Ali Sajassi
Cisco Systems

Email: sajassi@cisco.com

Samer Salam
Cisco Systems

Email: ssalam@cisco.com

John Drake
Juniper Networks

Email: jdrake@juniper.net

Jeff Tantsura
Individual
Email: jefftant@gmail.com

Dirk Steinberg
Steinberg Consulting
Email: dws@steinbergnet.net

Patrice Brissette
Cisco
Email: pbrisset@cisco.com

Thomas Beckhaus
Deutsche Telecom
Email: Thomas.Beckhaus@telekom.de

Jorge Rabadan
Nokia

Email: jorge.rabadan@nokia.com

Ryan Bickhart
Juniper Networks
Email: rbickhart@juniper.net