draft-ietf-bess-evpn-vpws-07.txt   draft-ietf-bess-evpn-vpws-08.txt 
INTERNET-DRAFT Sami Boutros INTERNET-DRAFT Sami Boutros
Intended Status: Standard Track VMware Intended Status: Standard Track VMware
Ali Sajassi Ali Sajassi
Samer Salam Samer Salam
Cisco Systems Cisco Systems
John Drake John Drake
Juniper Networks Juniper Networks
Jeff Tantsura
Individual
Dirk Steinberg
Steinberg Consulting
Thomas Beckhaus
Deutsche Telecom
J. Rabadan J. Rabadan
Nokia Nokia
Expires: January 6, 2017 July 5, 2016 Expires: August 11, 2017 February 7, 2017
VPWS support in EVPN VPWS support in EVPN
draft-ietf-bess-evpn-vpws-07.txt draft-ietf-bess-evpn-vpws-08.txt
Abstract Abstract
This document describes how EVPN can be used to support Virtual This document describes how EVPN can be used to support Virtual
Private Wire Service (VPWS) in MPLS/IP networks. EVPN enables the Private Wire Service (VPWS) in MPLS/IP networks. EVPN enables the
following characteristics for VPWS: single-active as well as all- following characteristics for VPWS: single-active as well as all-
active multi-homing with flow-based load-balancing, eliminates the active multi-homing with flow-based load-balancing, eliminates the
need for traditional way of PW signaling, and provides fast need for traditional way of PW signaling, and provides fast
protection convergence upon node or link failure. protection convergence upon node or link failure.
skipping to change at page 2, line 4 skipping to change at page 1, line 44
other groups may also distribute working documents as other groups may also distribute working documents as
Internet-Drafts. Internet-Drafts.
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."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html http://www.ietf.org/1id-abstracts.html
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html http://www.ietf.org/shadow.html
Copyright and License Notice Copyright and License Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Requirements . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2 Requirements . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Service interface . . . . . . . . . . . . . . . . . . . . . . . 6 2 Service interface . . . . . . . . . . . . . . . . . . . . . . . 6
2.1 VLAN-Based Service Interface . . . . . . . . . . . . . . . . 6 2.1 VLAN-Based Service Interface . . . . . . . . . . . . . . . . 6
2.2 VLAN Bundle Service Interface . . . . . . . . . . . . . . . 6 2.2 VLAN Bundle Service Interface . . . . . . . . . . . . . . . 6
2.2.1 Port-Based Service Interface . . . . . . . . . . . . . . 6 2.2.1 Port-Based Service Interface . . . . . . . . . . . . . . 7
2.3 VLAN-Aware Bundle Service Interface . . . . . . . . . . . . 7 2.3 VLAN-Aware Bundle Service Interface . . . . . . . . . . . . 7
3. BGP Extensions . . . . . . . . . . . . . . . . . . . . . . . . 7 3. BGP Extensions . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1 EVPN Layer 2 attributes extended community . . . . . . . . . 7 3.1 EVPN Layer 2 attributes extended community . . . . . . . . . 8
4 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5 EVPN Comparison to PW Signaling . . . . . . . . . . . . . . . . 10 5 EVPN Comparison to PW Signaling . . . . . . . . . . . . . . . . 11
6 Failure Scenarios . . . . . . . . . . . . . . . . . . . . . . . 11 6 Failure Scenarios . . . . . . . . . . . . . . . . . . . . . . . 11
6.1 Single-Homed CEs . . . . . . . . . . . . . . . . . . . . . . 11 6.1 Single-Homed CEs . . . . . . . . . . . . . . . . . . . . . . 11
6.2 Multi-Homed CEs . . . . . . . . . . . . . . . . . . . . . . 11 6.2 Multi-Homed CEs . . . . . . . . . . . . . . . . . . . . . . 12
7 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 11 7 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 12
8 Security Considerations . . . . . . . . . . . . . . . . . . . . 11 8 Security Considerations . . . . . . . . . . . . . . . . . . . . 12
9 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 11 9 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 12
10 References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 10 References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
10.1 Normative References . . . . . . . . . . . . . . . . . . . 12 10.1 Normative References . . . . . . . . . . . . . . . . . . . 12
10.2 Informative References . . . . . . . . . . . . . . . . . . 12 10.2 Informative References . . . . . . . . . . . . . . . . . . 13
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
1 Introduction 1 Introduction
This document describes how EVPN can be used to support Virtual This document describes how EVPN can be used to support Virtual
Private Wire Service (VPWS) in MPLS/IP networks. The use of EVPN Private Wire Service (VPWS) in MPLS/IP networks. The use of EVPN
mechanisms for VPWS brings the benefits of EVPN to p2p services. mechanisms for VPWS (EVPN-VPWS) brings the benefits of EVPN to p2p
These benefits include single-active redundancy as well as all-active services. These benefits include single-active redundancy as well as
redundancy with flow-based load-balancing. Furthermore, the use of all-active redundancy with flow-based load-balancing. Furthermore,
EVPN for VPWS eliminates the need for traditional way of PW signaling the use of EVPN for VPWS eliminates the need for traditional way of
for p2p Ethernet services, as described in section 4. PW signaling for p2p Ethernet services, as described in section 4.
[RFC7432] has the ability to forward customer traffic to/from a given [RFC7432] has the ability to forward customer traffic to/from a given
customer Attachment Circuit (AC), without any MAC lookup. This customer Attachment Circuit (AC), without any MAC lookup. This
capability is ideal in providing p2p services (aka VPWS services). capability is ideal in providing p2p services (aka VPWS services).
[MEF] defines Ethernet Virtual Private Line (EVPL) service as p2p [MEF] defines Ethernet Virtual Private Line (EVPL) service as p2p
service between a pair of ACs (designated by VLANs) and Ethernet service between a pair of ACs (designated by VLANs) and Ethernet
Private Line (EPL) service, in which all traffic flows are between a Private Line (EPL) service, in which all traffic flows are between a
single pair of ports, that in EVPN terminology would mean a single single pair of ports, that in EVPN terminology would mean a single
pair of ESes. EVPL can be considered as a VPWS with only two ACs. In pair of Ethernet Segments ES(es). EVPL can be considered as a VPWS
delivering an EVPL service, the traffic forwarding capability of EVPN with only two ACs. In delivering an EVPL service, the traffic
based on the exchange of a pair of Ethernet AD routes is used; forwarding capability of EVPN based on the exchange of a pair of
whereas, for more general VPWS, traffic forwarding capability of EVPN Ethernet Auto-discovery (A-D) routes is used; whereas, for more
general VPWS as per [RFC4664], traffic forwarding capability of EVPN
based on the exchange of a group of Ethernet AD routes (one Ethernet based on the exchange of a group of Ethernet AD routes (one Ethernet
AD route per AC/ES) is used. In a VPWS service, the traffic from an AD route per AC/ES) is used. In a VPWS service, the traffic from an
originating Ethernet Segment can be forwarded only to a single originating Ethernet Segment can be forwarded only to a single
destination Ethernet Segment; hence, no MAC lookup is needed and the destination Ethernet Segment; hence, no MAC lookup is needed and the
MPLS label associated with the per-EVI Ethernet AD route can be used MPLS label associated with the per EVPN instance (EVI) Ethernet A-D
in forwarding user traffic to the destination AC. route can be used in forwarding user traffic to the destination AC.
Both services are supported by using the per EVI Ethernet A-D route Both services are supported by using the per EVI Ethernet A-D route
which contains an Ethernet Segment Identifier, in which the customer which contains an Ethernet Segment Identifier, in which the customer
ES is encoded, and an Ethernet Tag, in which the VPWS service ES is encoded, and an Ethernet Tag, in which the VPWS service
instance identifier is encoded. I.e., for both EPL and EVPL instance identifier is encoded. I.e., for both EPL and EVPL
services, a specific VPWS service instance is identified by a pair of services, a specific VPWS service instance is identified by a pair of
per EVI Ethernet A-D routes which together identify the VPWS service per EVI Ethernet A-D routes which together identify the VPWS service
instance endpoints and the VPWS service instance. In the control instance endpoints and the VPWS service instance. In the control
plane the VPWS service instance is identified using the VPWS service plane the VPWS service instance is identified using the VPWS service
instance identifiers advertised by each PE and in the data plane the instance identifiers advertised by each PE and in the data plane the
value of the MPLS label advertised by one PE is used by the other PE 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 to send traffic for that VPWS service instance. As with the Ethernet
Tag in standard EVPN, the VPWS service instance identifier has Tag in standard EVPN, the VPWS service instance identifier has
uniqueness within an EVPN instance. uniqueness within an EVPN instance.
Unlike EVPN where Ethernet Tag ID in EVPN routes are set to zero for Unlike EVPN where Ethernet Tag ID in EVPN routes are set to zero for
Port-based, vlan-based, and vlan-bundle interface mode and it is set Port-based, vlan-based, and vlan-bundle interface mode and it is set
to non-zero Ethernet tag ID for vlan-aware bundle mode, in EVPN-VPWS, to non-zero Ethernet tag ID for vlan-aware bundle mode, in EVPN-VPWS,
for all the four interface modes, Ethernet tag ID in the Ethernet A-D for all the four interface modes, Ethernet tag ID in the Ethernet A-D
route MUST be set to a valid value in all the service interface route MUST be set to a non-zero value in all the service interface
types. 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 24-bit normalized Ethernet tag ID. The value of the MPLS serves as a 24-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 lookup of the MPLS disposition PE can identify the egress AC from the lookup of the MPLS
label alone and perform any required tag translation. For EVPL label alone and perform any required tag translation. For EVPL
service, the Ethernet frames transported over an MPLS/IP network service, the Ethernet frames transported over an MPLS/IP network
SHOULD remain tagged with the originating VID and any VID translation SHOULD remain tagged with the originating Vlan-ID (VID) and any VID
is performed at the disposition PE. For EPL service, the Ethernet translation MUST be performed at the disposition PE. For EPL service,
frames are transported as is and the tags are not altered. the 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 VNI The MPLS label value in the Ethernet A-D route can be set to the
for VxLAN encap, and this VNI may have a global scope or local scope VXLAN Network Identifier (VNI) for VxLAN encap, and this VNI may have
per PE and may also be made equal to the VPWS service instance a global scope or local scope per PE and may also be made equal to
identifier set in the Ethernet A-D route. the VPWS service instance identifier set in the Ethernet A-D route.
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 for
flow-based load-balancing and mass withdraw functions. flow-based load-balancing and mass withdraw functions as per
[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 and the Ethernet Segment route convergence upon link or node failure and the Ethernet Segment route
is used for auto-discovery of the PEs attached to a given multi-homed is used for auto-discovery of the PEs attached to a given multi-homed
CE and to synchronize state between them. 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
skipping to change at page 5, line 9 skipping to change at page 5, line 13
CE: Customer Edge device e.g., host or router or switch. CE: Customer Edge device e.g., host or router or switch.
EVPL: Ethernet Virtual Private Line. EVPL: Ethernet Virtual Private Line.
EPL: Ethernet Private Line. EPL: Ethernet Private Line.
EP-LAN: Ethernet Private LAN. EP-LAN: Ethernet Private LAN.
EVP-LAN: Ethernet Virtual Private LAN. EVP-LAN: Ethernet Virtual Private LAN.
S-VLAN: Service VLAN identifier.
C-VLAN: Customer VLAN identifier.
VPWS: Virtual Private Wire Service. VPWS: Virtual Private Wire Service.
EVI: EVPN Instance. EVI: EVPN Instance.
ES: Ethernet Segment on a PE refer to the link attached to it, this ES: Ethernet Segment on a PE refers to the link attached to it, this
link can be part of a set of links attached to different PEs in multi link can be part of a set of links attached to different PEs in multi
home cases, or could be a single link in single home cases. homed cases, or could be a single link in single homed cases.
ESI: Ethernet Segment Identifier.
Single-Active Mode: When a device or a network is multi-homed to two Single-Active Mode: When a device or a network is multi-homed to two
or more PEs and when only a single PE in such redundancy group can or more PEs and when only a single PE in such redundancy group can
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
labels associated with a pair of endpoints. Each label is 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.
1.2 Requirements 1.2 Requirements
1. EPL service access circuit maps to the whole Ethernet port. 1. EPL service access circuit MUST map to the whole Ethernet port.
2. EVPL service access circuits are VLANs on single or double tagged 2. EVPL service access circuit MUST map to an individual VLAN or
trunk ports. Each VLAN individually (or <S-VLAN,C-VLAN> combination) double tagged <S-VLAN,C-VLAN> combination on a given trunk port,
will be considered to be an endpoint for an EVPL service, without any without any direct dependency on any other VLANs on the same trunk.
direct dependency on any other VLANs on the trunk. Other VLANs on the Other VLANs on the same trunk MAY also be used for EVPL services, but
same trunk could also be used for EVPL services, but could also be MAY also be associated with other services.
associated with other services.
3. If multiple VLANs on the same trunk are associated with EVPL 3. If multiple VLANs on the same trunk are associated with EVPL
services, the respective remote endpoints of these EVPLs could be services, the respective remote endpoints of these EVPLs MAY be
dispersed across any number of PEs, i.e. different VLANs may lead to dispersed across any number of PEs, i.e. different VLANs MAY lead to
different destinations. different destinations.
4. The VLAN tag on the access trunk only has PE-local significance. 4. The VLAN tag on the access trunk MUST only have PE-local
The VLAN tag on the remote end could be different, and could also be significance. The VLAN tag on the remote end could be different, and
double tagged when the other side is single tagged. could also be double tagged when the other side is single tagged.
5. Also, multiple EVPL service VLANs on the same trunk could belong 5. Also, multiple EVPL service VLANs on the same trunk MAY belong to
to the same EVPN instance (EVI), or they could belong to different the same EVPN instance (EVI), or they MAY belong to different EVIs.
EVIs. This should be purely an administrative choice of the network This should be purely an administrative choice of the network
operator. operator.
6. A given PE could have thousands of EVPLs configured. It must be 6. A given PE MAY have thousands of EVPLs configured. It MUST be
possible to configure multiple EVPL services within the same EVI. possible to configure multiple EVPL services within the same EVI.
7. Local access circuits configured to belong to a given EVPN 7. Local access circuits configured to belong to a given EVPN
instance could also belong to different physical access trunks. instance MAY also belong to different physical access trunks.
8. EP-LAN and EVP-LAN are possible on the same system and also ESIs 8. EP-LAN and EVP-LAN MAY be possible on the same system and also
can be shared between EVPL and EVP-LANs. ESIs can be shared between EVPL and EVP-LANs.
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 MPLS LSP identified by the VPWS service functionality between MPLS LSP identified by the VPWS service
skipping to change at page 7, line 16 skipping to change at page 7, line 31
Contrary to EVPN, in EVPN-VPWS this service interface maps to VLAN- Contrary to EVPN, in EVPN-VPWS this service interface maps to 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, he would realize that it is the same as that of service interface, he would realize that it is the same as that of
VLAN-based service. VLAN-based service.
3. BGP Extensions 3. BGP Extensions
This document proposes 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 to
the customer ES and the Ethernet Tag ID 32-bit field is set to the the customer ES and the Ethernet Tag ID 32-bit field MUST be set to
24-bit VPWS service instance identifier. For both EPL and EVPL the 24-bit VPWS service instance identifier value. For both EPL and
services, for a given VPWS service instance the pair of PEs EVPL services, for a given VPWS service instance the pair of PEs
instantiating that VPWS service instance will each advertise a per instantiating that VPWS service instance will each advertise a per
EVI Ethernet A-D route with its VPWS service instance identifier and EVI Ethernet A-D route with its VPWS service instance identifier and
will each be configured with the other PE's VPWS service instance 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 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 A-D route the VPWS service instance is instantiated. It should be
noted that the same VPWS service instance identifier may be noted that the same VPWS service instance identifier may be
configured on both PEs. 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
skipping to change at page 7, line 46 skipping to change at page 8, line 14
3.1 EVPN Layer 2 attributes extended community 3.1 EVPN Layer 2 attributes extended community
This draft proposes a new extended community, defined below, to be This draft proposes a new extended community, defined below, to be
included with the per EVI Ethernet A-D route. This attribute is included with the per EVI Ethernet A-D route. 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) |
+------------------------------------+ +------------------------------------+
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)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
skipping to change at page 8, line 17 skipping to change at page 8, line 34
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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.
SHOULD be set to 1 for multihoming all-active scenarios. MUST be set to 1 for multihoming all-active scenarios by
all active 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 sending EVPN packets to this PE. when sending EVPN packets to this PE.
L2 MTU (Maximum Transmission Unit) is a 2-octet value indicating the
MTU in octets.
A received L2 MTU=0 means no MTU checking against local MTU is A received L2 MTU=0 means no MTU checking against local MTU is
needed. A received non-zero MTU SHOULD be checked against local MTU needed. A received non-zero MTU MUST be checked against local MTU and
and if there is a mismatch, the local PE MUST NOT add the remote PE if there is a mismatch, the local PE MUST NOT add the remote PE as
as the EVPN destination for the corresponding VPWS service instance. the EVPN destination for the corresponding VPWS service instance.
The usage of the Per ES Ethernet AD route is unchanged from its usage The usage of the Per ES Ethernet A-D route is unchanged from its
in [RFC7432], i.e. the "Single-Active" bit in the flags of the ESI usage in [RFC7432], i.e. the "Single-Active" bit in the flags of the
Label extended community will indicate if single-active or all-active ESI Label extended community will indicate if single-active or all-
redundancy is used for this ES. active redundancy is used for this ES.
In multihoming scenarios, both B and P flags MUST NOT be both set. 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
unset, it MUST NOT forward any traffic to the sender PE.
In a multihoming all-active scenario, there is no DF election, and In a multihoming all-active scenario, there is no DF election, and
all the PEs in the ES that are active and ready to forward traffic all the PEs in the ES that are active and ready to forward traffic
to/from the CE will set the P bit to 1. A remote PE will do per-flow to/from the CE will set the P bit to 1. A remote PE will do per-flow
load balancing to the PEs that send P=1 for the same Ethernet Tag and load balancing to the PEs that send P=1 for the same Ethernet Tag and
ESI. ESI. B bit in control flags SHOULD not be set in the multihoming all-
active scenario and MUST be ignored by receiving PE(s) if set.
In multihoming single-active scenario, the DF election will determine In multihoming single-active scenario, the DF election will determine
who the primary and the backup PEs are, and only those PEs will set who the primary and the backup PEs are, and only those PEs will set
the P bit and B bit respectively. A remote PE will forward the the P bit and B bit respectively. A remote PE will forward the
traffic to the primary PE and switch over to the backup PE as soon as traffic to the primary PE and switch over to the backup PE as soon as
it receives an Ethernet A-D route withdrawal from the primary PE in it receives an Ethernet A-D route withdrawal from the primary PE in
the Ethernet Segment. the Ethernet Segment.
In multihoming single-active scenario, during transient situations, a In multihoming single-active scenario, during transient situations, a
remote PE receiving P=1 from more than one PE will select the last remote PE receiving P=1 from more than one PE will select the last
advertising PE as the primary PE when forwarding traffic. A remote PE advertising PE as the primary PE when forwarding traffic. A remote PE
receiving B=1 from more than one PE will select only one backup PE. A receiving B=1 from more than one PE will select only one backup PE. A
remote PE MUST receive P=1 from at least one PE before forwarding remote PE MUST receive P=1 from at least one PE before forwarding
traffic. traffic.
As per [RFC6790], if a network uses entropy labels then the control If a network uses entropy labels per [RFC6790] then the C Bit MUST
word (C bit set) SHOULD NOT be used when sending EVPN-encapsulated not be set to 1 and control word MUST NOT be used when sending EVPN-
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.
Ethernet Ethernet Ethernet Ethernet
Native |<--------- EVPN Instance ----------->| Native Native |<--------- EVPN Instance ----------->| Native
Service | | Service Service | | Service
(AC) | |<-PSN1->| |<-PSN2->| | (AC) (AC) | |<-PSN1->| |<-PSN2->| | (AC)
| V V V V V V | | V V V V V V |
skipping to change at page 9, line 35 skipping to change at page 10, line 15
| |-------+-----+ +-----+ +-----+ +-----+-------| | | |-------+-----+ +-----+ +-----+ +-----+-------| |
+----+ | | 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 1: EVPN-VPWS Deployement 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 Next Hop AS option B, the ASBRs re-advertise these routes with NEXT_HOP
attribute set to their IP addresses. The link between the CE and the attribute set to their IP addresses as per [RFC4271]. The link
PE is either a C-tagged or S-tagged interface, as described in between the CE and the PE is either a C-tagged or S-tagged interface,
[802.1Q], that can carry a single VLAN tag or two nested VLAN tags as described in [802.1Q], that can carry a single VLAN tag or two
and it is configured as a trunk with multiple VLANs, one per VPWS nested VLAN tags and it is configured as a trunk with multiple VLANs,
service instance. It should be noted that the VLAN ID used by the one per VPWS service instance. It should be noted that the VLAN ID
customer at either end of a VPWS service instance to identify that used by the customer at either end of a VPWS service instance to
service instance may be different and EVPN doesn't perform that identify that service instance may be different and EVPN doesn't
translation between the two values. Rather, the MPLS label will perform that translation between the two values. Rather, the MPLS
identify the VPWS service instance and if translation is needed, it label will identify the VPWS service instance and if translation is
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 field 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 field 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 to perform on all PEs attached to that ES. This allows an ingress PE to perform
flow-based load-balancing of traffic flows to all of the PEs attached flow-based load-balancing of traffic flows to all of the PEs attached
to that ES. In all cases traffic follows the transport paths, which to that ES. In all cases traffic follows the transport paths, which
may be asymmetric. may be asymmetric.
The VPWS service instance identifier encoded in the Ethernet Tag The VPWS service instance identifier encoded in the Ethernet Tag ID
field in an advertised per EVI Ethernet A-D route MUST either be in an advertised per EVI Ethernet A-D route MUST either be unique
unique across all ASs, or an ASBR needs to perform a translation when across all ASs, or an ASBR needs to perform a translation when the
the per EVI Ethernet A-D route is re-advertised by the ASBR from one per EVI Ethernet A-D route is re-advertised by the ASBR from one AS
AS to the other AS. to the other AS.
Per ES Ethernet A-D route can be used for mass withdraw to withdraw 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
skipping to change at page 11, line 14 skipping to change at page 11, line 41
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 backup by the backup PE to encapsulate the traffic and direct it to backup
PE. 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 AD 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 AD 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, upon a link/port
failure of this single-homed Ethernet Segment, the PE MUST withdraw failure of this single-homed Ethernet Segment, the PE MUST withdraw
the associated per EVI Ethernet A-D routes. 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, mass withdraw technique Active Redundancy or All-active redundancy, mass withdraw technique
as per [RFC7432] baseline is used. A PE previously advertising a per is used. A PE previously advertising a per ES Ethernet A-D route, can
ES Ethernet A-D route, can withdraw this route signaling to the withdraw this route signaling to the remote PEs to switch all the
remote PEs to switch all the VPWS service instances associated with VPWS service instances associated with this multi-homed ES to the
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 and Vinod Prabhu for their feedback and Singh, Senthil Sathappan and Vinod Prabhu 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 equally
applicable. 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 [ietf-evpn-overlay] are equally applicable. and in [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 0x04 EVPN Layer 2 attributes [RFCXXXX]
EVPN Layer 2 attributes [RFCXXXX]
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, DOI 10.17487/RFC2119, March
1997, <http://www.rfc-editor.org/info/rfc2119>. 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 Ethernet
skipping to change at page 12, line 26 skipping to change at page 13, line 4
[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 Ethernet
VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015, <http://www.rfc- VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015, <http://www.rfc-
editor.org/info/rfc7432>. editor.org/info/rfc7432>.
[RFC4448] Martini, L., Rosen, E., El-Aawar, N., and G. Heron, [RFC4448] Martini, L., 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 Networks",
RFC 4448, April 2006. RFC 4448, April 2006.
[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and L. [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and L.
Yong, "The Use of Entropy Labels in MPLS Forwarding", November 2012. Yong, "The Use of Entropy Labels in MPLS Forwarding", November 2012.
[RFC7153] Rosen, E. and Y. Rekhter, "IANA Registries for BGP Extended
Communities", RFC 7153, March 2014, <http://www.rfc-
editor.org/info/rfc7153>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border
Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006, <http://www.rfc-
editor.org/info/rfc4271>.
[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>.
10.2 Informative References 10.2 Informative References
[MEF] Metro Ethernet Forum, "Ethernet Services Definitions - Phase [MEF] Metro Ethernet Forum, "Ethernet Services Definitions - Phase
2", Technical Specification MEF 6.1, April 2008, 2", Technical Specification MEF 6.1, April 2008,
<http://metroethernetforum.org/Assets/Technical_Specifications/PDF/ <http://metroethernetforum.org/Assets/Technical_Specifications/PDF/
MEF6-1.pdf>. MEF6-1.pdf>.
[ietf-evpn-overlay] Sajassi-Drake et al., "A Network Virtualization
Overlay Solution using EVPN", draft-ietf-bess-evpn-overlay-07.txt,
work in progress, December, 2016
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
Sami Boutros Sami Boutros
skipping to change at page 13, line 29 skipping to change at page 14, line 22
Dirk Steinberg Dirk Steinberg
Steinberg Consulting Steinberg Consulting
Email: dws@steinbergnet.net Email: dws@steinbergnet.net
Patrice Brissette Patrice Brissette
Cisco Cisco
Email: pbrisset@cisco.com Email: pbrisset@cisco.com
Thomas Beckhaus Thomas Beckhaus
Deutsche Telecom Deutsche Telecom
Email:Thomas.Beckhaus@telekom.de Email: Thomas.Beckhaus@telekom.de
Jorge Rabadan Jorge Rabadan
Nokia Nokia
Email: jorge.rabadan@nokia.com Email: jorge.rabadan@nokia.com
Ryan Bickhart Ryan Bickhart
Juniper Networks Juniper Networks
Email: rbickhart@juniper.net Email: rbickhart@juniper.net
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