draft-ietf-bess-evpn-vpws-14v3updated.txt   draft-ietf-bess-evpn-vpws-14v3.txt 
skipping to change at line 13 skipping to change at page 1, line 14
Internet-Draft VMware Internet-Draft VMware
Intended status: Standards Track A. Sajassi Intended status: Standards Track A. Sajassi
Expires: November 15, 2017 S. Salam Expires: November 15, 2017 S. Salam
Cisco Systems Cisco Systems
J. Drake J. Drake
Juniper Networks Juniper Networks
J. Rabadan J. Rabadan
Nokia Nokia
May 14, 2017 May 14, 2017
Virtual Private Wire Service support in Ethernet VPN Virtual Private Wire Service support in Ethernet VPN
draft-ietf-bess-evpn-vpws-14.txt draft-ietf-bess-evpn-vpws-14.txt
Abstract Abstract
This document describes how Ethernet VPN (EVPN) can be used to This document describes how Ethernet VPN (EVPN) can be used to
support Virtual Private Wire Service (VPWS) in MPLS/IP networks. EVPN support Virtual Private Wire Service (VPWS) in MPLS/IP networks.
enables the following characteristics for VPWS: single-active as well EVPN enables the following characteristics for VPWS: single-active as
as all-active multi-homing with flow-based load-balancing, eliminates well as all-active multi-homing with flow-based load-balancing,
the need for Pseudowire (PW) signaling, and provides fast protection eliminates the need for Pseudowire (PW) signaling, and provides fast
convergence upon node or link failure. protection convergence upon node or link failure.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 26, 2017. This Internet-Draft will expire on November 15, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Service interface . . . . . . . . . . . . . . . . . . . . . . . 4 2. Service interface . . . . . . . . . . . . . . . . . . . . . . 6
2.1. VLAN-Based Service Interface . . . . . . . . . . . . . . . 4 2.1. VLAN-Based Service Interface . . . . . . . . . . . . . . 6
2.2. VLAN Bundle Service Interface . . . . . . . . . . . . . . 5 2.2. VLAN Bundle Service Interface . . . . . . . . . . . . . . 6
2.2.1. Port-Based Service Interface . . . . . . . . . . . 5 2.2.1. Port-Based Service Interface . . . . . . . . . . . . 6
2.3. VLAN-Aware Bundle Service Interface . . . . . . . . . . . 6 2.3. VLAN-Aware Bundle Service Interface . . . . . . . . . . . 6
3. BGP Extensions . . . . . . . . . . . . . . . . . . . . . . . . 6 3. BGP Extensions . . . . . . . . . . . . . . . . . . . . . . . 7
3.1. EVPN Layer 2 attributes extended community . . . . . . . . 6 3.1. EVPN Layer 2 attributes extended community . . . . . . . 7
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5. EVPN Comparison to PW Signaling . . . . . . . . . . . . . . . . 7 5. EVPN Comparison to PW Signaling . . . . . . . . . . . . . . . 10
6. Failure Scenarios . . . . . . . . . . . . . . . . . . . . . . . 7 6. Failure Scenarios . . . . . . . . . . . . . . . . . . . . . . 11
6.1. Single-Homed CEs . . . . . . . . . . . . . . . . . . . . . 7 6.1. Single-Homed CEs . . . . . . . . . . . . . . . . . . . . 11
6.2. Multi-Homed CEs . . . . . . . . . . . . . . . . . . . . . 8 6.2. Multi-Homed CEs . . . . . . . . . . . . . . . . . . . . . 11
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
8. Security Considerations . . . . . . . . . . . . . . . . . . . . 8 8. Security Considerations . . . . . . . . . . . . . . . . . . . 12
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
10.1. Normative References . . . . . . . . . . . . . . . . . . 9 10.1. Normative References . . . . . . . . . . . . . . . . . . 12
10.2. Informative References . . . . . . . . . . . . . . . . . 9 10.2. Informative References . . . . . . . . . . . . . . . . . 13
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction 1. Introduction
This document describes how EVPN can be used to support VPWS in This document describes how EVPN can be used to support VPWS in MPLS/
MPLS/IP networks. The use of EVPN mechanisms for VPWS (EVPN-VPWS) IP networks. The use of EVPN mechanisms for VPWS (EVPN-VPWS) brings
brings the benefits of EVPN to Point to Point (P2P) services. These the benefits of EVPN to Point to Point (P2P) services. These
benefits include single-active redundancy as well as all-active benefits include single-active redundancy as well as all-active
redundancy with flow-based load-balancing. Furthermore, the use of redundancy with flow-based load-balancing. Furthermore, the use of
EVPN for VPWS eliminates the need for traditional way of PW signaling EVPN for VPWS eliminates the need for traditional way of PW signaling
for P2P Ethernet services, as described in section 4. for P2P Ethernet services, as described in section 4.
[RFC7432] provides the ability to forward customer traffic to/from a [RFC7432] provides the ability to forward customer traffic to/from a
given customer Attachment Circuit (AC), without any Media Access given customer Attachment Circuit (AC), without any Media Access
Control (MAC) lookup. This capability is ideal in providing P2P Control (MAC) lookup. This capability is ideal in providing P2P
services (aka VPWS services). [MEF] defines Ethernet Virtual Private services (aka VPWS services). [MEF] defines Ethernet Virtual Private
Line (EVPL) service as P2P service between a pair of ACs (designated Line (EVPL) service as P2P service between a pair of ACs (designated
by VLANs) and Ethernet Private Line (EPL) service, in which all by VLANs) and Ethernet Private Line (EPL) service, in which all
traffic flows are between a single pair of ports, that in EVPN traffic flows are between a single pair of ports, that in EVPN
terminology would mean a single pair of Ethernet Segments ES(es). 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 can be considered as a VPWS with only two ACs. In delivering an
EVPL service, the traffic forwarding capability of EVPN is based on EVPL service, the traffic forwarding capability of EVPN is based on
the exchange of a pair of Ethernet Auto-discovery (A-D) routes; the exchange of a pair of Ethernet Auto-discovery (A-D) routes;
whereas, for more general VPWS as per [RFC4664], traffic forwarding whereas, for more general VPWS as per [RFC4664], traffic forwarding
capability of EVPN is based on the exchange of a group of Ethernet AD capability of EVPN is based on the exchange of a group of Ethernet AD
routes (one Ethernet AD route per AC/ES). In a VPWS service, the routes (one Ethernet AD route per AC/ES). In a VPWS service, the
traffic from an originating Ethernet Segment can be forwarded only to traffic from an originating Ethernet Segment can be forwarded only to
a single destination Ethernet Segment; hence, no MAC lookup is needed a single destination Ethernet Segment; hence, no MAC lookup is needed
and the MPLS label associated with the per EVPN instance (EVI) and the MPLS label associated with the per EVPN instance (EVI)
Ethernet A-D route can be used in forwarding user traffic to the Ethernet A-D route can be used in forwarding user traffic to the
destination AC. destination AC.
For both EPL and EVPL services, a specific VPWS service instance is For both EPL and EVPL services, a specific VPWS service instance is
identified by a pair of per-EVI Ethernet A-D routes which together identified by a pair of per-EVI Ethernet A-D routes which together
identify the VPWS service instance endpoints and the VPWS service identify the VPWS service instance endpoints and the VPWS service
instance. In the control plane the VPWS service instance is instance. In the control plane the VPWS service instance is
identified using the VPWS service instance identifiers advertised by identified using the VPWS service instance identifiers advertised by
each Provider Edge node (PE). In the data plane the value of the MPLS each Provider Edge node (PE). In the data plane the value of the
label advertised by one PE is used by the other PE to send traffic MPLS label advertised by one PE is used by the other PE to send
for that VPWS service instance. As with the Ethernet Tag in standard traffic for that VPWS service instance. As with the Ethernet Tag in
EVPN, the VPWS service instance identifier has uniqueness within an standard EVPN, the VPWS service instance identifier has uniqueness
EVPN instance. within an EVPN instance.
For EVPN routes, the Ethernet Tag IDs are set to zero for Port-based, For EVPN routes, the Ethernet Tag IDs are set to zero for Port-based,
VLAN-based, and VLAN-bundle interface mode and set to non-zero VLAN-based, and VLAN-bundle interface mode and set to non-zero
Ethernet Tag IDs for VLAN-aware bundle mode. Conversely, for EVPN- Ethernet Tag IDs for VLAN-aware bundle mode. Conversely, for EVPN-
VPWS, the Ethernet Tag ID in the Ethernet A-D route MUST be set to a 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. non-zero value for all four service interface types.
In terms of route advertisement and MPLS label lookup behavior, EVPN- In terms of route advertisement and MPLS label lookup behavior, EVPN-
VPWS resembles the VLAN-aware bundle mode of [RFC7432] such that when VPWS resembles the VLAN-aware bundle mode of [RFC7432] such that when
a PE advertises per-EVI Ethernet A-D route, the VPWS service instance a PE advertises per-EVI Ethernet A-D route, the VPWS service instance
serves as a 32-bit normalized Ethernet Tag ID. The value of the MPLS 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 label in this route represents both the EVI and the VPWS service
instance, so that upon receiving an MPLS encapsulated packet, the instance, so that upon receiving an MPLS encapsulated packet, the
disposition PE can identify the egress AC from the MPLS label and disposition PE can identify the egress AC from the MPLS label and
subsequently perform any required tag translation. For EVPL service, subsequently perform any required tag translation. For EVPL service,
the Ethernet frames transported over an MPLS/IP network SHOULD remain the Ethernet frames transported over an MPLS/IP network SHOULD remain
tagged with the originating VLAN-ID (VID) and any VID translation tagged with the originating VLAN-ID (VID) and any VID translation
MUST be performed at the disposition PE. For EPL service, the MUST be performed at the disposition PE. For EPL service, the
Ethernet frames are transported as is and the tags are not altered. Ethernet frames are transported as is and the tags are not altered.
The MPLS label value in the Ethernet A-D route can be set to the The MPLS label value in the Ethernet A-D route can be set to the
Virtual Extensible LAN (VXLAN) Network Identifier (VNI) for VXLAN Virtual Extensible LAN (VXLAN) Network Identifier (VNI) for VXLAN
encapsulation as per [RFC7348], and this VNI will have a local scope 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 per PE and may also be equal to the VPWS service instance identifier
set in the Ethernet A-D route. When using VXLAN encap, the BGP set in the Ethernet A-D route. When using VXLAN encap, the BGP
Encapsulation extended community is included in the Ethernet A-D Encapsulation extended community is included in the Ethernet A-D
route as described in [I-D.ietf-evpn-overlay]. The VXLAN VNI like the route as described in [I-D.ietf-evpn-overlay]. The VXLAN VNI like
MPLS label that will be set in the tunnel header used to tunnel the MPLS label that will be set in the tunnel header used to tunnel
Ethernet packets from all the service interface types defined in Ethernet packets from all the service interface types defined in
section 2. The EVPN-VPWS techniques defined in this document has no section 2. The EVPN-VPWS techniques defined in this document has no
dependency on the tunneling technology. dependency on the tunneling technology.
The Ethernet Segment identifier encoded in the Ethernet A-D per-EVI The Ethernet Segment identifier encoded in the Ethernet A-D per-EVI
route is not used to identify the service. However it can be used for route is not used to identify the service. However it can be used
flow-based load-balancing and mass withdraw functions as per the for flow-based load-balancing and mass withdraw functions as per the
[RFC7432] baseline. [RFC7432] baseline.
As with standard EVPN, the Ethernet A-D per-ES route is used for fast 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 convergence upon link or node failure. The Ethernet Segment route is
used for auto-discovery of the PEs attached to a given multi-homed used for auto-discovery of the PEs attached to a given multi-homed
Customer Edge node (CE) and to synchronize state between them. Customer Edge node (CE) and to synchronize state between them.
1.1. Terminology 1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
EVPN: Ethernet VPN EVPN: Ethernet VPN
skipping to change at line 234 skipping to change at page 5, line 45
forward traffic to/from the multi-homed device or network for a given forward traffic to/from the multi-homed device or network for a given
VLAN, then such multi-homing or redundancy is referred to as "Single- VLAN, then such multi-homing or redundancy is referred to as "Single-
Active". Active".
All-Active: When a device is multi-homed to two or more PEs and when All-Active: When a device is multi-homed to two or more PEs and when
all PEs in such redundancy group can forward traffic to/from the all PEs in such redundancy group can forward traffic to/from the
multi-homed device for a given VLAN, then such multi-homing or multi-homed device for a given VLAN, then such multi-homing or
redundancy is referred to as "All-Active". redundancy is referred to as "All-Active".
VPWS Service Instance: It is represented by a pair of EVPN service VPWS Service Instance: It is represented by a pair of EVPN service
labels associated with a pair of endpoints. Each label is downstream labels associated with a pair of endpoints. Each label is downstream
assigned and advertised by the disposition PE through an Ethernet A-D assigned and advertised by the disposition PE through an Ethernet A-D
per-EVI route. The downstream label identifies the endpoint on the per-EVI route. The downstream label identifies the endpoint on the
disposition PE. A VPWS service instance can be associated with only disposition PE. A VPWS service instance can be associated with only
one VPWS service identifier. one VPWS service identifier.
2. Service interface 2. Service interface
2.1. VLAN-Based Service Interface 2.1. VLAN-Based Service Interface
With this service interface, a VPWS instance identifier corresponds With this service interface, a VPWS instance identifier corresponds
to only a single VLAN on a specific interface. Therefore, there is a 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 one-to-one mapping between a VID on this interface and the VPWS
service instance identifier. The PE provides the cross-connect service instance identifier. The PE provides the cross-connect
functionality between an MPLS LSP identified by the VPWS service functionality between an MPLS LSP identified by the VPWS service
instance identifier and a specific <port,VLAN>. If the VLAN is instance identifier and a specific <port,VLAN>. If the VLAN is
represented by different VIDs on different PEs and different ES(es), represented by different VIDs on different PEs and different ES(es),
(e.g., a different VID per Ethernet segment per PE), then each PE (e.g., a different VID per Ethernet segment per PE), then each PE
needs to perform VID translation for frames destined to its Ethernet needs to perform VID translation for frames destined to its Ethernet
segment. In such scenarios, the Ethernet frames transported over an segment. In such scenarios, the Ethernet frames transported over an
MPLS/IP network SHOULD remain tagged with the originating VID, and a MPLS/IP network SHOULD remain tagged with the originating VID, and a
VID translation MUST be supported in the data path and MUST be VID translation MUST be supported in the data path and MUST be
performed on the disposition PE. performed on the disposition PE.
2.2. VLAN Bundle Service Interface 2.2. VLAN Bundle Service Interface
With this service interface, a VPWS service instance identifier With this service interface, a VPWS service instance identifier
corresponds to multiple VLANs on a specific interface. The PE corresponds to multiple VLANs on a specific interface. The PE
provides the cross-connect functionality between the MPLS label provides the cross-connect functionality between the MPLS label
identified by the VPWS service instance identifier and a group of identified by the VPWS service instance identifier and a group of
VLANs on a specific interface. For this service interface, each VLAN VLANs on a specific interface. For this service interface, each VLAN
is presented by a single VID which means no VLAN translation is is presented by a single VID which means no VLAN translation is
allowed. The receiving PE, can direct the traffic based on EVPN label allowed. The receiving PE, can direct the traffic based on EVPN
alone to a specific port. The transmitting PE can cross-connect label alone to a specific port. The transmitting PE can cross-
traffic from a group of VLANs on a specific port to the MPLS label. connect traffic from a group of VLANs on a specific port to the MPLS
The MPLS-encapsulated frames MUST remain tagged with the originating label. The MPLS-encapsulated frames MUST remain tagged with the
VID. originating VID.
2.2.1. Port-Based Service Interface 2.2.1. Port-Based Service Interface
This service interface is a special case of the VLAN bundle service 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 interface, where all of the VLANs on the port are mapped to the same
VPWS service instance identifier. The procedures are identical to VPWS service instance identifier. The procedures are identical to
those described in Section 2.2. those described in Section 2.2.
2.3. VLAN-Aware Bundle Service Interface 2.3. VLAN-Aware Bundle Service Interface
Contrary to EVPN, in EVPN-VPWS this service interface maps to a VLAN- Contrary to EVPN, in EVPN-VPWS this service interface maps to a VLAN-
based service interface (defined in section 2.1) and thus this based service interface (defined in section 2.1) and thus this
service interface is not used in EVPN-VPWS. In other words, if one service interface is not used in EVPN-VPWS. In other words, if one
tries to define data plane and control plane behavior for this tries to define data plane and control plane behavior for this
service interface, one would realize that it is the same as that of service interface, one would realize that it is the same as that of
VLAN-based service. VLAN-based service.
3. BGP Extensions 3. BGP Extensions
This document specifies the use of the per-EVI Ethernet A-D route to This document specifies the use of the per-EVI Ethernet A-D route to
signal VPWS services. The Ethernet Segment Identifier field is set to signal VPWS services. The Ethernet Segment Identifier field is set
the customer ES and the Ethernet Tag ID 32-bit field MUST be set to to the customer ES and the Ethernet Tag ID 32-bit field MUST be set
the VPWS service instance identifier value. The VPWS service instance to the VPWS service instance identifier value. The VPWS service
identifier value MAY be set to a 24-bit value and when a 24-bit value instance identifier value MAY be set to a 24-bit value and when a
is used, it MUST be right aligned. For both EPL and EVPL services 24-bit value is used, it MUST be right aligned. For both EPL and
using a given VPWS service instance, the pair of PEs instantiating EVPL services using a given VPWS service instance, the pair of PEs
that VPWS service instance will each advertise a per-EVI Ethernet A-D instantiating that VPWS service instance will each advertise a per-
route with its VPWS service instance identifier and will each be EVI Ethernet A-D route with its VPWS service instance identifier and
configured with the other PE's VPWS service instance identifier. When will each be configured with the other PE's VPWS service instance
each PE has received the other PE's per-EVI Ethernet A-D route, the identifier. When each PE has received the other PE's per-EVI
VPWS service instance is instantiated. It should be noted that the Ethernet A-D route, the VPWS service instance is instantiated. It
same VPWS service instance identifier may be configured on both PEs. should be noted that the same VPWS service instance identifier may be
configured on both PEs.
The Route-Target (RT) extended community with which the per-EVI The Route-Target (RT) extended community with which the per-EVI
Ethernet A-D route is tagged identifies the EVPN instance in which Ethernet A-D route is tagged identifies the EVPN instance in which
the VPWS service instance is configured. It is the operator's choice 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 as to how many and which VPWS service instances are configured in a
given EVPN instance. However, a given EVPN instance MUST NOT be given EVPN instance. However, a given EVPN instance MUST NOT be
configured with both VPWS service instances and standard EVPN multi- configured with both VPWS service instances and standard EVPN multi-
point services. point services.
3.1. EVPN Layer 2 attributes extended community 3.1. EVPN Layer 2 attributes extended community
This document defines a new extended community [RFC4360], to be This document defines a new extended community [RFC4360], to be
included with per-EVI Ethernet A-D routes. This attribute is included with per-EVI Ethernet A-D routes. This attribute is
mandatory if multihoming is enabled. mandatory if multihoming is enabled.
+------------------------------------+ +------------------------------------+
| Type(0x06)/Sub-type(0x04)(2 octet)| | Type(0x06)/Sub-type(0x04)(2 octet) |
+------------------------------------+ +------------------------------------+
| Control Flags (2 octets) | | Control Flags (2 octets) |
+------------------------------------+ | L2 MTU (2 octets) |
| L2 MTU (2 octets) | | Reserved (2 octets) |
+------------------------------------+ +------------------------------------+
| Reserved (2 octets) |
+------------------------------------+
Figure 1: EVPN Layer 2 attributes extended community Table 1: EVPN Layer 2 attributes extended community
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MBZ |C|P|B| (MBZ = MUST Be Zero) | MBZ |C|P|B| (MBZ = MUST Be Zero)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: EVPN Layer 2 attributes Control Flags Figure 1: EVPN Layer 2 attributes Control Flags
The following bits in the Control Flags are defined; the remaining The following bits in the Control Flags are defined; the remaining
bits MUST be set to zero when sending and MUST be ignored when bits MUST be set to zero when sending and MUST be ignored when
receiving this community. receiving this community.
Name Meaning Name Meaning
P If set to 1 in multihoming single-active scenarios, it P If set to 1 in multihoming single-active scenarios, it
indicates that the advertising PE is the Primary PE. indicates that the advertising PE is the Primary PE. MUST be
MUST be set to 1 for multihoming all-active scenarios by set to 1 for multihoming all-active scenarios by all active
all active PE(s). PE(s).
B If set to 1 in multihoming single-active scenarios, it B If set to 1 in multihoming single-active scenarios, it
indicates that the advertising PE is the Backup PE. indicates that the advertising PE is the Backup PE.
C If set to 1, a Control word [RFC4448] MUST be present C If set to 1, a Control word [RFC4448] MUST be present when
when sending EVPN packets to this PE. It is recommended to sending EVPN packets to this PE. It is recommended to include
include the control word in the absence of Entropy Label. the control word in the absence of Entropy Label.
L2 MTU (Maximum Transmission Unit) is a 2-octet value indicating the L2 MTU (Maximum Transmission Unit) is a 2-octet value indicating the
MTU in bytes. MTU in bytes.
A received L2 MTU of zero means no MTU checking against local MTU is A received L2 MTU of zero means no MTU checking against local MTU is
needed. A received non-zero MTU MUST be checked against local MTU and needed. A received non-zero MTU MUST be checked against local MTU
if there is a mismatch, the local PE MUST NOT add the remote PE as and if there is a mismatch, the local PE MUST NOT add the remote PE
the EVPN destination for the corresponding VPWS service instance. as the EVPN destination for the corresponding VPWS service instance.
The usage of the Per ES Ethernet A-D route is unchanged from its The usage of the Per ES Ethernet A-D route is unchanged from its
usage in [RFC7432], i.e., the "Single-Active" bit in the flags of the 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- ESI Label extended community will indicate if single-active or all-
active redundancy is used for this ES. active redundancy is used for this ES.
In multihoming scenarios, the B and P flags MUST be cleared. A PE 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 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 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 the sender PE. clear, it MUST treat the route as a withdrawal from the sender PE.
In a multihoming all-active scenario, there is no Designated In a multihoming all-active scenario, there is no Designated
Forwarder (DF) election, and all the PEs in the ES that are active 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 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 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 Flag for the same Ethernet Tag and ESI. The B Flag in control flags
SHOULD NOT be set in the multihoming all-active scenario and MUST be SHOULD NOT be set in the multihoming all-active scenario and MUST be
ignored by receiving PE(s) if set. ignored by receiving PE(s) if set.
In multihoming single-active scenario for a given VPWS service In multihoming single-active scenario for a given VPWS service
instance, the DF election should result in the Primary-elected PE for instance, the DF election should result in the Primary-elected PE for
the VPWS service instance advertising the P Flag set and the B Flag the VPWS service instance advertising the P Flag set and the B Flag
clear, the Backup elected PE should advertise the P Flag clear and clear, the 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 the B Flag set, and the rest of the PEs in the same ES should signal
both P and B Flags clear. When the primary PE/ES fails, the primary both P and B Flags clear. When the primary PE/ES fails, the primary
PE will withdraw the associated Ethernet A-D routes for the VPWS PE will withdraw the associated Ethernet A-D routes for the VPWS
service instance from the remote PE and the remote PEs should then service instance from the remote PE and the remote PEs should then
send traffic associated with the VPWS instance to the backup PE. DF 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 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 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 will signal the P and B Flags as described. A remote PE SHOULD
receive the P Flag set from only one Primary PE and the B Flag set receive the P Flag set from only one Primary PE and the B Flag set
from only one Backup PE. However during transient situations, a from only one Backup PE. However during transient situations, a
remote PE receiving a P Flag set from more than one PE will select 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 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 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 P the last advertising PE as the backup PE. A remote PE MUST receive P
Flag set from at least one PE before forwarding traffic. Flag set from at least one PE before forwarding traffic.
If a network uses entropy labels per [RFC6790] then the C Flag MUST If a network uses entropy labels per [RFC6790] then the C Flag MUST
NOT be set and control word MUST NOT be used when sending EVPN- NOT be set and control word MUST NOT be used when sending EVPN-
encapsulated packets over a P2P LSP. encapsulated packets over a P2P LSP.
4. Operation 4. Operation
The following figure shows an example of a P2P service deployed with The following figure shows an example of a P2P service deployed with
EVPN. EVPN.
skipping to change at line 428 skipping to change at page 9, line 49
| |-------+-----+ +-----+ +-----+ +-----+-------| | | |-------+-----+ +-----+ +-----+ +-----+-------| |
+----+ | | PE2 |======|ASBR3|==|ASBR4|===| PE4 | | +----+ +----+ | | PE2 |======|ASBR3|==|ASBR4|===| PE4 | | +----+
^ +-----+ +-----+ +-----+ +-----+ ^ ^ +-----+ +-----+ +-----+ +-----+ ^
| Provider Edge 1 ^ Provider Edge 2 | | Provider Edge 1 ^ Provider Edge 2 |
| | | | | |
| | | | | |
| EVPN Inter-provider point | | EVPN Inter-provider point |
| | | |
|<---------------- Emulated Service -------------------->| |<---------------- Emulated Service -------------------->|
Figure 3: EVPN-VPWS Deployment Model Figure 2: EVPN-VPWS Deployment Model
iBGP sessions are established between PE1, PE2, ASBR1 and ASBR3, iBGP sessions are established between PE1, PE2, ASBR1 and ASBR3,
possibly via a BGP route-reflector. Similarly, iBGP sessions are possibly via a BGP route-reflector. Similarly, iBGP sessions are
established between PE3, PE4, ASBR2 and ASBR4. eBGP sessions are established between PE3, PE4, ASBR2 and ASBR4. eBGP sessions are
established among ASBR1, ASBR2, ASBR3, and ASBR4. established among ASBR1, ASBR2, ASBR3, and ASBR4.
All PEs and ASBRs are enabled for the EVPN SAFI and exchange per-EVI All PEs and ASBRs are enabled for the EVPN SAFI and exchange per-EVI
Ethernet A-D routes, one route per VPWS service instance. For inter- Ethernet A-D routes, one route per VPWS service instance. For inter-
AS option B, the ASBRs re-advertise these routes with the NEXT_HOP AS option B, the ASBRs re-advertise these routes with the NEXT_HOP
attribute set to their IP addresses as per [RFC4271]. The link 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, 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 as described in [802.1Q], that can carry a single VLAN tag or two
nested VLAN tags and it is configured as a trunk with multiple VLANs, nested VLAN tags and it is configured as a trunk with multiple VLANs,
one per VPWS service instance. It should be noted that the VLAN ID 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 used by the customer at either end of a VPWS service instance to
identify that service instance may be different and EVPN doesn't identify that service instance may be different and EVPN doesn't
perform that translation between the two values. Rather, the MPLS perform that translation between the two values. Rather, the MPLS
label will identify the VPWS service instance and if translation is label will identify the VPWS service instance and if translation is
needed, it should be done by the Ethernet interface for each service. needed, it should be done by the Ethernet interface for each service.
For single-homed CE, in an advertised per-EVI Ethernet A-D route the For single-homed CE, in an advertised per-EVI Ethernet A-D route the
ESI field is set to 0 and the Ethernet Tag ID is set to the VPWS ESI field is set to 0 and the Ethernet Tag ID is set to the VPWS
service instance identifier that identifies the EVPL or EPL service. service instance identifier that identifies the EVPL or EPL service.
For a multi-homed CE, in an advertised per-EVI Ethernet A-D route the For a multi-homed CE, in an advertised per-EVI Ethernet A-D route the
ESI field is set to the CE's ESI and the Ethernet Tag ID is set to 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 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 on all PEs attached to that ES. This allows an ingress PE in a
multihoming all-active scenario to perform flow-based load-balancing multihoming all-active scenario to perform flow-based load-balancing
of traffic flows to all of the PEs attached to that ES. In all cases of traffic flows to all of the PEs attached to that ES. In all cases
traffic follows the transport paths, which may be asymmetric. traffic follows the transport paths, which may be asymmetric.
The VPWS service instance identifier encoded in the Ethernet Tag ID The VPWS service instance identifier encoded in the Ethernet Tag ID
in an advertised per-EVI Ethernet A-D route MUST either be unique in an advertised per-EVI Ethernet A-D route MUST either be unique
across all ASs, or an ASBR needs to perform a translation when the across all ASs, or an ASBR needs to perform a translation when the
per-EVI Ethernet A-D route is re-advertised by the ASBR from one AS per-EVI Ethernet A-D route is re-advertised by the ASBR from one AS
to the other AS. to the other AS.
A per-ES Ethernet A-D route can be used for mass withdraw to withdraw 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 site all per-EVI Ethernet A-D routes associated with the multi-home site
on a given PE. on a given PE.
5. EVPN Comparison to PW Signaling 5. EVPN Comparison to PW Signaling
In EVPN, service endpoint discovery and label signaling are done In EVPN, service endpoint discovery and label signaling are done
concurrently using BGP. Whereas, with VPWS based on [RFC4448], label concurrently using BGP. Whereas, with VPWS based on [RFC4448], label
signaling is done via LDP and service endpoint discovery is either signaling is done via LDP and service endpoint discovery is either
through manual provisioning or through BGP. through manual provisioning or through BGP.
In existing implementations of VPWS using pseudowires(PWs), In existing implementations of VPWS using pseudowires(PWs),
redundancy is limited to single-active mode, while with EVPN redundancy is limited to single-active mode, while with EVPN
implementation of VPWS both single-active and all-active redundancy implementation of VPWS both single-active and all-active redundancy
modes can be supported. modes can be supported.
In existing implementations with PWs, backup PWs are not used to In existing implementations with PWs, backup PWs are not used to
carry traffic, while with EVPN, traffic can be load-balanced among carry traffic, while with EVPN, traffic can be load-balanced among
different PEs multi-homed to a single CE. different PEs multi-homed to a single CE.
Upon link or node failure, EVPN can trigger failover with the Upon link or node failure, EVPN can trigger failover with the
withdrawal of a single BGP route per EVPL service or multiple EVPL withdrawal of a single BGP route per EVPL service or multiple EVPL
services, whereas with VPWS PW redundancy, the failover sequence services, whereas with VPWS PW redundancy, the failover sequence
requires exchange of two control plane messages: one message to requires exchange of two control plane messages: one message to
deactivate the group of primary PWs and a second message to activate deactivate the group of primary PWs and a second message to activate
the group of backup PWs associated with the access link. the group of backup PWs associated with the access link.
Finally, EVPN may employ data plane egress link protection mechanisms Finally, EVPN may employ data plane egress link protection mechanisms
not available in VPWS. This can be done by the primary PE (on local 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 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 by the backup PE to encapsulate the traffic and direct it to the
backup PE. backup PE.
6. Failure Scenarios 6. Failure Scenarios
On a link or port failure between the CE and the PE for both single On a link or port failure between the CE and the PE for both single
and multi-homed CEs, unlike [RFC7432] the PE MUST withdraw all the and multi-homed CEs, unlike [RFC7432] the PE MUST withdraw all the
associated Ethernet A-D routes for the VPWS service instances on the associated Ethernet A-D routes for the VPWS service instances on the
failed port or link. failed port or link.
6.1. Single-Homed CEs 6.1. Single-Homed CEs
Unlike [RFC7432], EVPN-VPWS uses Ethernet A-D route advertisements Unlike [RFC7432], EVPN-VPWS uses Ethernet A-D route advertisements
for single-homed Ethernet Segments. Therefore, upon a link/port for single-homed Ethernet Segments. Therefore,
failure of this single-homed Ethernet Segment, the PE MUST withdraw upon a link/port failure of this single-homed
the associated per-EVI Ethernet A-D routes. Ethernet Segment, the PE MUST withdraw the
associated per-EVI Ethernet A-D routes.
6.2. Multi-Homed CEs 6.2. Multi-Homed CEs
For a faster convergence in multi-homed scenarios with either Single- For a faster convergence in multi-homed scenarios with either Single-
Active Redundancy or All-active redundancy, a mass withdraw technique Active Redundancy or All-active redundancy, a mass withdraw technique
is used. A PE previously advertising a per-ES Ethernet A-D route, can is used. A PE previously advertising a per-ES Ethernet A-D route,
withdraw this route by signaling to the remote PEs to switch all the can withdraw this route by signaling to the remote PEs to switch all
VPWS service instances associated with this multi-homed ES to the the VPWS service instances associated with this multi-homed ES to the
backup PE. backup PE.
7. Acknowledgements 7. Acknowledgements
The authors would like to acknowledge Jeffrey Zhang, Wen Lin, Nitin The authors would like to acknowledge Jeffrey Zhang, Wen Lin, Nitin
Singh, Senthil Sathappan, Vinod Prabhu, Himanshu Shah, Iftekhar Singh, Senthil Sathappan, Vinod Prabhu, Himanshu Shah, Iftekhar
Hussain, Alvaro Retana and Acee Lindem for their feedback and Hussain, Alvaro Retana and Acee Lindem for their feedback and
contributions to this document. contributions to this document.
8. Security Considerations 8. Security Considerations
The mechanisms in this document use EVPN control plane as defined in The mechanisms in this document use EVPN control plane as defined in
[RFC7432]. Security considerations described in [RFC7432] are equally [RFC7432]. Security considerations described in [RFC7432] are
applicable. equally applicable.
This document uses MPLS and IP-based tunnel technologies to support This document uses MPLS and IP-based tunnel technologies to support
data plane transport. Security considerations described in [RFC7432] data plane transport. Security considerations described in [RFC7432]
and in [I-D.ietf-evpn-overlay] are equally applicable. and in [I-D.ietf-evpn-overlay] are equally applicable.
9. IANA Considerations 9. IANA Considerations
IANA has allocated the following EVPN Extended Community sub-type: IANA has allocated the following EVPN Extended Community sub-type:
SUB-TYPE VALUE NAME Reference SUB-TYPE VALUE NAME Reference
0x04 EVPN Layer 2 Attributes [RFCXXXX] 0x04 EVPN Layer 2 Attributes [RFCXXXX]
This document creates a registry called "EVPN Layer 2 Attributes This document creates a registry called "EVPN Layer 2 Attributes
Control Flags". New registrations will be made through the "RFC Control Flags". New registrations will be made through the "RFC
Required" procedure defined in [RFC5226]. Required" procedure defined in [RFC5226].
Initial registrations are as follows: Initial registrations are as follows:
P Advertising PE is the Primary PE. P Advertising PE is the Primary PE.
B Advertising PE is the Backup PE. B Advertising PE is the Backup PE.
C Control word [RFC4448] MUST be present. C Control word [RFC4448] MUST be present.
10. References 10. References
10.1. Normative References 10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March Requirement Levels", BCP 14, RFC 2119,
1997, <http://www.rfc-editor.org/info/rfc2119>. DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., [RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015, <http://www.rfc- Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
editor.org/info/rfc7432>. 2015, <http://www.rfc-editor.org/info/rfc7432>.
[RFC4448] Martini, L., Rosen, E., El-Aawar, N., and G. Heron, [RFC4448] Martini, L., Ed., Rosen, E., El-Aawar, N., and G. Heron,
"Encapsulation Methods for Transport of Ethernet over MPLS Networks", "Encapsulation Methods for Transport of Ethernet over MPLS
RFC 4448, April 2006. Networks", RFC 4448, DOI 10.17487/RFC4448, April 2006,
<http://www.rfc-editor.org/info/rfc4448>.
[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and L. [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and
Yong, "The Use of Entropy Labels in MPLS Forwarding", November 2012. L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
November 2012.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006, <http://www.rfc- Border Gateway Protocol 4 (BGP-4)", RFC 4271,
editor.org/info/rfc4271>. DOI 10.17487/RFC4271, January 2006,
<http://www.rfc-editor.org/info/rfc4271>.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, February 2006, <http://www.rfc- Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
editor.org/info/rfc4360>. February 2006, <http://www.rfc-editor.org/info/rfc4360>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008, IANA Considerations Section in RFCs", RFC 5226,
<http://www.rfc-editor.org/info/rfc5226>. DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[RFC7348] Mahalingam, M., "VXLAN: A Framework for Overlaying [RFC7348] Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
Virtualized Layer 2 Networks over Layer 3 Networks", RFC 7348, August L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
2014. 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,
<http://www.rfc-editor.org/info/rfc7348>.
10.2. Informative References 10.2. Informative References
[MEF] Metro Ethernet Forum, "Ethernet Services Definitions - Phase [MEF] Metro Ethernet Forum, "Ethernet Services Definitions -
2", Technical Specification MEF 6.1, April 2008, Phase 2", Technical Specification MEF 6.1, April 2008,
https://www.mef.net/Assets/Technical_Specifications/PDF/MEF_6.1.pdf <https://www.mef.net/Assets/Technical_Specifications/PDF/
MEF_6.1.pdf>.
[RFC4664] Andersson, L., Ed., and E. Rosen, Ed., "Framework for
Layer 2 Virtual Private Networks (L2VPNs)", RFC 4664, September 2006,
<http://www.rfc-editor.org/info/rfc4664>.
[I-D.ietf-evpn-overlay] Drake, J., "A Network Virtualization [RFC4664] Andersson, L., Ed. and E. Rosen, Ed., "Framework for Layer
Overlay Solution using EVPN", draft-ietf-bess-evpn-overlay-07, 2 Virtual Private Networks (L2VPNs)", RFC 4664,
(work in progress), December 2016. DOI 10.17487/RFC4664, September 2006,
<http://www.rfc-editor.org/info/rfc4664>.
Contributors Contributors
In addition to the authors listed on the front page, the following In addition to the authors listed on the front page, the following
co-authors have also contributed to this document: co-authors have also contributed to this document:
Daniel Voyer Bell Canada Daniel Voyer Bell Canada
Authors' Addresses Authors' Addresses
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