draft-ietf-bess-evpn-vpws-03.txt   draft-ietf-bess-evpn-vpws-04.txt 
skipping to change at page 1, line 23 skipping to change at page 1, line 23
Jeff Tantsura Jeff Tantsura
Ericsson Ericsson
Dirk Steinberg Dirk Steinberg
Steinberg Consulting Steinberg Consulting
Thomas Beckhaus Thomas Beckhaus
Deutsche Telecom Deutsche Telecom
J. Rabadan J. Rabadan
Alcatel-Lucent Nokia
Expires: September 17, 2016 March 16, 2016 Expires: December 8, 2016 June 6, 2016
VPWS support in EVPN VPWS support in EVPN
draft-ietf-bess-evpn-vpws-03.txt draft-ietf-bess-evpn-vpws-04.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 single-segment and multi-segment PW signaling, and provides need for traditional way of PW signaling, and provides fast
fast protection using data-plane prefix independent convergence upon protection convergence upon node or link failure.
node or link failure.
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF 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), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as other groups may also distribute working documents as
Internet-Drafts. Internet-Drafts.
skipping to change at page 2, line 37 skipping to change at page 2, line 36
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 . . . . . . . . . . . . . . . . . . . . . . . . . 4 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 5 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2 Requirements . . . . . . . . . . . . . . . . . . . . . . . . 6 1.2 Requirements . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Service interface . . . . . . . . . . . . . . . . . . . . . . . 6 2 Service interface . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 VLAN-Based Service Interface . . . . . . . . . . . . . . . . 6 2.1 VLAN-Based Service Interface . . . . . . . . . . . . . . . . 7
2.2 VLAN Bundle Service Interface . . . . . . . . . . . . . . . 7 2.2 VLAN Bundle Service Interface . . . . . . . . . . . . . . . 7
2.2.1 Port-Based Service Interface . . . . . . . . . . . . . . 7 2.2.1 Port-Based Service Interface . . . . . . . . . . . . . . 7
2.3 VLAN-Aware Bundle Service Interface . . . . . . . . . . . . 7 2.3 VLAN-Aware Bundle Service Interface . . . . . . . . . . . . 8
2.4 Flexible CrossConnect Service . . . . . . . . . . . . . . . 7
3. BGP Extensions . . . . . . . . . . . . . . . . . . . . . . . . 8 3. BGP Extensions . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1 EVPN Layer 2 attributes extended community . . . . . . . . . 9 3.1 EVPN Layer 2 attributes extended community . . . . . . . . . 8
4 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5 EVPN Comparison to PW Signaling . . . . . . . . . . . . . . . . 12 5 EVPN Comparison to PW Signaling . . . . . . . . . . . . . . . . 11
6 ESI Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . 12 6 Failure Scenarios . . . . . . . . . . . . . . . . . . . . . . . 12
7 Failure Scenarios . . . . . . . . . . . . . . . . . . . . . . . 12 6.1 Single-Homed CEs . . . . . . . . . . . . . . . . . . . . . . 12
7.1 Single-Homed CEs . . . . . . . . . . . . . . . . . . . . . . 13 6.2 Multi-Homed CEs . . . . . . . . . . . . . . . . . . . . . . 12
7.2 Multi-Homed CEs . . . . . . . . . . . . . . . . . . . . . . 13 7 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 12
8 VPWS with multiple sites . . . . . . . . . . . . . . . . . . . . 13 8 Security Considerations . . . . . . . . . . . . . . . . . . . . 12
9 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 13 9 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 12
10 Security Considerations . . . . . . . . . . . . . . . . . . . . 13 10 References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
11 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 13 10.1 Normative References . . . . . . . . . . . . . . . . . . . 13
12 References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 10.2 Informative References . . . . . . . . . . . . . . . . . . 13
12.1 Normative References . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
12.2 Informative References . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
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 brings the benefits of EVPN to p2p services.
These benefits include single-active redundancy as well as all-active These 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 signaling single-segment and EVPN for VPWS eliminates the need for traditional way of PW signaling
multi-segment PWs for p2p Ethernet services. for p2p Ethernet services, as described in section 4.
[EVPN] has the ability to forward customer traffic to/from a given [EVPN] has the ability to forward customer traffic to/from a given
customer Attachment Circuit (AC), aka Ethernet Segment in EVPN customer Attachment Circuit (AC), without any MAC lookup. This
terminology, without any MAC lookup. This capability is ideal in capability is ideal in providing p2p services (aka VPWS services).
providing p2p services (aka VPWS services). [MEF] defines Ethernet [MEF] defines Ethernet Virtual Private Line (EVPL) service as p2p
Virtual Private Line (EVPL) service as p2p service between a pair of service between a pair of ACs (designated by VLANs) and Ethernet
ACs (designated by VLANs) and Ethernet Private Line (EPL) service, in Private Line (EPL) service, in which all traffic flows are between a
which all traffic flows are between a single pair of ESes. EVPL can single pair of ports, that in EVPN terminology would mean a single
be considered as a VPWS with only two ACs. In delivering an EVPL pair of ESes. EVPL can be considered as a VPWS with only two ACs. In
service, the traffic forwarding capability of EVPN based on the delivering an EVPL service, the traffic forwarding capability of EVPN
exchange of a pair of Ethernet AD routes is used; whereas, for more based on the exchange of a pair of Ethernet AD routes is used;
general VPWS, traffic forwarding capability of EVPN based on the whereas, for more general VPWS, traffic forwarding capability of EVPN
exchange of a group of Ethernet AD routes (one Ethernet AD route per based on the exchange of a group of Ethernet AD routes (one Ethernet
AC/segment) 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-EVI Ethernet AD route can be used
in forwarding user traffic to the destination AC. in forwarding user traffic to the destination AC.
Both services are supported by using the Ethernet A-D per EVI 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
Ethernet A-D per EVI 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
MPLS label advertised by one PE is used by the other PE to send value of the MPLS label advertised by one PE is used by the other PE
traffic for that VPWS service instance. As with the Ethernet Tag in to send traffic for that VPWS service instance. As with the Ethernet
standard EVPN, the VPWS service instance identifier has uniqueness Tag in standard EVPN, the VPWS service instance identifier has
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. route MUST be set to a valid value in all the 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 [RFC 7432] such that VPWS resembles the vlan-aware bundle mode of [RFC 7432] such that
when a PE advertises Ethernet A-D per EVI route, the VPWS service when a PE advertises per EVI Ethernet A-D route, the VPWS service
instance serves as a 24-bit normalized Ethernet tag ID. The MPLS instance serves as a 24-bit normalized Ethernet tag ID. The value of
label in this route represents both the EVI and the VPWS service the MPLS label in this route represents both the EVI and the VPWS
instance, so that upon receiving an MPLS encapsulated packet, the service instance, so that upon receiving an MPLS encapsulated packet,
disposition PE can identify the egress AC from the lookup of the MPLS the disposition PE can identify the egress AC from the lookup of the
label alone and perform any required tag translation. For EVPL MPLS label alone and perform any required tag translation. For EVPL
service, the Ethernet frames transported over an MPLS/IP network MUST service, the Ethernet frames transported over an MPLS/IP network
remain tagged with the originating VID and any VID translation is SHOULD remain tagged with the originating VID and any VID translation
performed at the disposition PE. For EPL service, the Ethernet frames is performed at the disposition PE. For EPL service, the Ethernet
are transported as is and the tags are not altered. 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
for VxLAN encap, and this VNI may have a global scope or local scope
per PE and may also be made equal to 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 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.
skipping to change at page 5, line 47 skipping to change at page 6, line 5
OAM: Operations, Administration and Maintenance. OAM: Operations, Administration and Maintenance.
PE: Provide Edge Node. PE: Provide Edge Node.
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.
VPWS: Virtual private wire service. EP-LAN: Ethernet Private LAN.
EVP-LAN: Ethernet Virtual Private LAN.
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
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.
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".
1.2 Requirements 1.2 Requirements
1. EPL service access circuit maps to the whole Ethernet port. 1. EPL service access circuit maps to the whole Ethernet port.
2. EVPL service access circuits are VLANs on single or double tagged 2. EVPL service access circuits are VLANs on single or double tagged
trunk ports. Each VLAN individually will be considered to be an trunk ports. Each VLAN individually (or <S-VLAN,C-VLAN> combination)
endpoint for an EVPL service, without any direct dependency on any will be considered to be an endpoint for an EVPL service, without any
other VLANs on the trunk. Other VLANs on the same trunk could also be direct dependency on any other VLANs on the trunk. Other VLANs on the
used for EVPL services, but could also be associated with other same trunk could also be used for EVPL services, but could also be
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 could 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 only has PE-local significance.
The VLAN tag on the remote end could be different, and could also be The VLAN tag on the remote end could be different, and could also be
double tagged when the other side is single tagged. 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 could belong
to the same EVPN instance (EVI), or they could belong to different to the same EVPN instance (EVI), or they could belong to different
EVIs. This should be purely an administrative choice of the network EVIs. This should be purely an administrative choice of the network
operator. operator.
6. A given access trunk could have hundreds of EVPL services, and a 6. A given PE could have thousands of EVPLs configured. It must be
given PE could 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 could also belong to different physical access trunks.
8. EPL-LAN and EVP-LAN are possible on the same system and also ESIs 8. EP-LAN and EVP-LAN are possible on the same system and also ESIs
can be shared between EVPL and EVP-LANs. 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
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. (e.g., a different represented by different VIDs on different PEs. (e.g., a different
VID per Ethernet segment per PE), then each PE needs to perform VID VID per Ethernet segment per PE), then each PE needs to perform VID
translation for frames destined to its Ethernet segment. In such translation for frames destined to its Ethernet segment. In such
scenarios, the Ethernet frames transported over an MPLS/IP network scenarios, the Ethernet frames transported over an MPLS/IP network
skipping to change at page 7, line 22 skipping to change at page 7, line 36
translation for frames destined to its Ethernet segment. In such translation for frames destined to its Ethernet segment. In such
scenarios, the Ethernet frames transported over an MPLS/IP network scenarios, the Ethernet frames transported over an MPLS/IP network
SHOULD remain tagged with the originating VID, and a VID translation SHOULD remain tagged with the originating VID, and a VID translation
MUST be supported in the data path and MUST be performed on the MUST be supported in the data path and MUST be performed on the
disposition PE. 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 MPLS LSP identified provides the cross-connect functionality between MPLS label
by the VPWS service instance identifier and a group of VLANs on a identified by the VPWS service instance identifier and a group of
specific interface. For this service interface, each VLAN is VLANs on a specific interface. For this service interface, each VLAN
presented by a single VID which means no VLAN translation is allowed. is presented by a single VID which means no VLAN translation is
The receiving PE, can direct the traffic based on EVPN label alone to allowed. The receiving PE, can direct the traffic based on EVPN label
a specific port. The transmitting PE can corss connect traffic from a alone to a specific port. The transmitting PE can cross connect
group of VLANs on a specific port to the MPLS LSP. The MPLS- traffic from a group of VLANs on a specific port to the MPLS label.
encapsulated frames MUST remain tagged with the originating VID. The MPLS-encapsulated frames MUST remain tagged with the 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 6.2. 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 VLAN- Contrary to EVPN, in EVPN-VPWS this service interface maps to VLAN-
based service interface (defined in section 6.1) 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.
2.4 Flexible CrossConnect Service
This service provides the ultimate flexibility at the expense of
additional lookup. With this EVPN-VPWS service a large number of
attachments circuits (ACs), each of which represented by either
single VLAN tag or double VLAN tags (QinQ) across multiple endpoints,
are multiplexed in a single EVPN-VPWS service instance. An endpoint
can be a physical interface, VSI, an IP-VRF, a MAC-VRF, or any other
endpoint where cross-connection of the associated AC is desired.
Because in this service mode, aggregation is performed across
multiple endpoints, besides MPLS label, an additional VLAN ID lookup
(either single tag or double tag) needs to be performed at the
disposition PE in order to identify the destination endpoint. One can
think of this as, the EVPN label identifies a cross-connect table and
then a single tag (or double tag) lookup is performed to identify the
endpoint. Each cross-connect table has its own unique VLAN space
which mean it can have upto 4K single-tag VLAN (or upto 16M double-
tag VLANs). VLAN IDs can be overlap across different cross-connect
tables but MUST be unique within a table.
The EVPN label besides identifying the cross-connect table, also
identifies the following types of VID look-ups: Single VID lookup:
The disposition PE MUST support single VID lookup where upon outer-
VID lookup, the destination end-point is identified. Double VID
lookup: The disposition PE MUST support double VID lookup where upon
outer most two VIDs lookup, the destination end-point is identified.
Wildcard VID Lookup: The disposition PE MAY support special double
VID lookup where the first VID is outer most VID and the 2nd VID is
the wild card (*).
If no entry is found upon the lookup, a counter per cross-connect
table is incremented. Upon finding an entry and identifying the
destination endpoint, the packet is forwarded to that destination
endpoint. Any further tag manipulation such as re-write (single or
double), addition, deletion (single or double) will be performed at
the endpoint.
On the imposition PE, by associating an attachment circuit to an
EVPN-VPWS service instance ID, we basically associate that attachment
circuit with the corresponding cross-connect table.
Since VID lookup (single or double) needs to be performed at the
disposition PE, then VID normalization MUST be performed prior to the
MPLS encapsulation on the ingress PE. This requires that both
imposition and disposition PE devices be capable of VLAN tag
manipulation, such as re-write (single or double), addition, deletion
(single or double), at their endpoints (e.g., their physical
interfaces).
3. BGP Extensions 3. BGP Extensions
This document proposes the use of the Ethernet A-D per EVI route to
This document proposes 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 is set to the
24-bit VPWS service instance identifier. For both EPL and EVPL 24-bit VPWS service instance identifier. For both EPL and EVPL
services, for a given VPWS service instance the pair of PEs services, for a given VPWS service instance the pair of PEs
instantiating that VPWS service instance will each advertise an instantiating that VPWS service instance will each advertise a per
Ethernet A-D per EVI route with its VPWS service instance identifier EVI Ethernet A-D route with its VPWS service instance identifier and
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 Ethernet A-D per identifier. When each PE has received the other PE's per EVI Ethernet
EVI 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 Ethernet A-D The Route-Target (RT) extended community with which the per EVI
per EVI route is tagged identifies the EVPN instance in which the Ethernet A-D route is tagged identifies the EVPN instance in which
VPWS service instance is configured. It is the operator's choice as the VPWS service instance is configured. It is the operator's choice
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 draft proposes a new extended community, defined below, to be This draft proposes a new extended community, defined below, to be
included with Ethernet A-D per EVI route. This attribute is mandatory included with the per EVI Ethernet A-D route. This attribute is
if multihoming is enabled. mandatory if multihoming is enabled.
+------------------------------------+ +------------------------------------+
| Type(0x06)/Sub-type(TBD)(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 10, line 7 skipping to change at page 9, line 15
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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
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. SHOULD be set to 1 for multihoming all-active scenarios.
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 [RFC 4448] MUST be present C If set to 1, a Control word [RFC 4448] MUST be present
when sending EVPN packets to this PE. when sending EVPN packets to this PE.
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 SHOULD be checked against local MTU
and if there is a mismatch, the local PE MUST not add the remote PE and if there is a mismatch, the local PE MUST not add the remote PE
as the EVPN destination for corresponding VPWS service instance. as 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 AD route is unchanged from its usage
in [RFC7432], i.e. the "Single-Active" bit in the flags of the ESI in [RFC7432], i.e. the "Single-Active" bit in the flags of the ESI
Label extended community will indicate if single active or all active Label extended community will indicate if single-active or all-active
redundancy is used for this ES. redundancy is used for this ES.
In multihoming single active scenario, a remote PE receiving P=1 from In a multihoming all-active scenario, there is no DF election, and
more than one PE will select only one primary PE when forwarding all the PEs in the ES that are active and ready to forward traffic
traffic. A remote PE receiving B=1 from more than one PE will select to/from the CE will set the P bit to 1. A remote PE will do per-flow
only one backup PE. A remote PE MUST receive P=1 from at least one PE load balancing to the PEs that send P=1 for the same Ethernet Tag and
before forwarding traffic. ESI.
In multihoming single-active scenario, the DF election will determine
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
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
the Ethernet Segment.
In multihoming single-active scenario, during transient situations, a
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
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
traffic.
As per [RFC6790], if a network uses entropy labels then the control As per [RFC6790], if a network uses entropy labels then the control
word (C bit set) SHOULD not be used when sending EVPN-encapsulated word (C bit set) SHOULD not be used when sending EVPN-encapsulated
packets over a P2P LSP. 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
skipping to change at page 11, line 17 skipping to change at page 10, line 40
| | | | | |
| EVPN Inter-provider point | | EVPN Inter-provider point |
| | | |
|<---------------- Emulated Service -------------------->| |<---------------- Emulated Service -------------------->|
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 Ethernet All PEs and ASBRs are enabled for the EVPN SAFI and exchange per EVI
A-D per EVI 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. The link between the CE and the
PE is either a C-tagged or S-tagged interface, as described in PE is either a C-tagged or S-tagged interface, as described in
[802.1Q], that can carry a single VLAN tag or two nested VLAN tags [802.1Q], that can carry a single VLAN tag or two nested VLAN tags
and it is configured as a trunk with multiple VLANs, one per VPWS and it is configured as a trunk with multiple VLANs, one per VPWS
service instance. It should be noted that the VLAN ID used by the service instance. It should be noted that the VLAN ID used by the
customer at either end of a VPWS service instance to identify that customer at either end of a VPWS service instance to identify that
service instance may be different and EVPN doesn't perform that service instance may be different and EVPN doesn't perform that
translation between the two values. Rather, the MPLS label will translation between the two values. Rather, the MPLS label will
identify the VPWS service instance and if translation is needed, it identify the VPWS service instance and if translation is needed, it
should be done by the Ethernet interface for each service. should be done by the Ethernet interface for each service.
For single-homed CE, in an advertised Ethernet A-D per EVI 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 field 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 Ethernet A-D per EVI 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 field 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
field in an advertised Ethernet A-D per EVI route MUST either be field 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 unique across all ASs, or an ASBR needs to perform a translation when
the Ethernet A-D per EVI route is re-advertised by the ASBR from one the per EVI Ethernet A-D route is re-advertised by the ASBR from one
AS to the other AS. AS to the other AS.
Ethernet A-D per ES route can be used for mass withdraw to withdraw Per ES Ethernet A-D route can be used for mass withdraw to withdraw
all Ethernet A-D per EVI 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 implementation of VPWS using pseudowires(PWs), redundancy In existing implementation of VPWS using pseudowires(PWs), redundancy
skipping to change at page 12, line 26 skipping to change at page 11, line 50
In existing implementation with PWs, backup PWs are not used to carry In existing implementation with PWs, backup PWs are not used to carry
traffic, while with EVPN, traffic can be load-balanced among 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. Finally, the group of backup PWs associated with the access link.
EVPN may employ data plane local repair mechanisms not available in
VPWS.
6 ESI Bandwidth
The ESI Bandwidth will be encoded using the Link Bandwidth Extended
community defined in [draft-ietf-idr-link-bandwidth] and associated
with the Ethernet AD route used to realize the EVPL services.
When a PE receives this attribute for a given EVPL it MUST request
the required bandwidth from the PSN towards the other EVPL service
destination PE originating the message. When resources are allocated
from the PSN for a given EVPL service, then the PSN SHOULD account
for the Bandwidth requested by this EVPL service.
In the case where PSN resources are not available, the PE receiving
this attribute MUST re-send its local Ethernet AD routes for this
EVPL service with the ESI Bandwidth = All FFs to declare that the
"PSN Resources Unavailable".
The scope of the ESI Bandwidth is limited to only one Autonomous Finally, EVPN may employ data plane egress link protection mechanisms
System. not available in VPWS. This can be done by the primary PE (on local
AC down) using the label advertised in the per EVI Ethernet A-D route
by the backup PE to encapsulate the traffic and direct it to backup
PE.
7 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, the PE must withdraw all the associated Ethernet and multi-homed CEs, unlike [EVPN] the PE must withdraw all the
AD routes for the VPWS service instances on the failed port or link. associated Ethernet AD routes for the VPWS service instances on the
failed port or link.
7.1 Single-Homed CEs 6.1 Single-Homed CEs
Unlike [EVPN], EVPN-VPWS uses Ethernet AD route advertisements for Unlike [EVPN], EVPN-VPWS uses Ethernet AD route advertisements for
single-homed Ethernet Segments. Therefore, upon a link/port failure single-homed Ethernet Segments. Therefore, upon a link/port failure
of this single-homed Ethernet Segment, the PE MUST withdraw the of this single-homed Ethernet Segment, the PE MUST withdraw the
associated Ethernet A-D routes. associated per EVI Ethernet A-D routes.
7.2 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 [EVPN] baseline is used. A PE previously advertising an as per [EVPN] baseline is used. A PE previously advertising a per ES
Ethernet A-D per ES route, can withdraw this route signaling to the Ethernet A-D route, can withdraw this route signaling to the remote
remote PEs to switch all the VPWS service instances associated with PEs to switch all the VPWS service instances associated with this
this multi-homed ES to the backup PE multi-homed ES to the backup PE
8 VPWS with multiple sites 7 Acknowledgements
The VPWS among multiple sites (full mesh of P2P connections - one per The authors would like to acknowledge Jeffrey Zhang, Wen Lin, Nitin
pair of sites) that can be setup automatically without any explicit Singh, Senthil Sathappan and Vinod Prabhu for their feedback and
provisioning of P2P connections among the sites is outside the scope contributions to this document.
of this document.
9 Acknowledgements 8 Security Considerations
The authors would like to acknowledge Wen Lin, Nitin Singh, Senthil The mechanisms in this document use EVPN control plane as defined in
Sathappan and Vinod Prabhu for their feedback and contributions to [RFC7432]. Security considerations described in [RFC7432] are equally
this document. applicable.
10 Security Considerations This document uses MPLS and IP-based tunnel technologies to support
data plane transport. Security considerations described in [RFC7432]
and in [ietf-evpn-overlay] are equally applicable.
This document does not introduce any additional security constraints. 9 IANA Considerations
11 IANA Considerations IANA has allocated the following EVPN Extended Community sub-type in
Allocation of Extended Community Type and Sub-Type for EVPN L2 [RFC7153].
attributes.
12 References 0x04 EVPN Layer 2 attributes [RFCXXXX]
12.1 Normative References 10 References
10.1 Normative References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
12.2 Informative References [RFC7432] A. Sajassi, R. Aggarwal et. al., "BGP MPLS Based Ethernet
[RFC7209] A. Sajassi, R. Aggarwal et. al., "Requirements for Ethernet
VPN". VPN".
[RFC7432] A. Sajassi, R. Aggarwal et. al., "BGP MPLS Based Ethernet 10.2 Informative References
[RFC7209] A. Sajassi, R. Aggarwal et. al., "Requirements for Ethernet
VPN". VPN".
[PBB-EVPN] A. Sajassi et. al., "PBB-EVPN", draft-ietf-l2vpn-pbb-evpn- [RFC7623] A. Sajassi et. al., "PBB-EVPN", "Provider Backbone Bridging
08.txt. Combined with Ethernet VPN (PBB-EVPN)".
[RFC4761] Kompella, K. and Y. Rekhter, "Virtual Private LAN Service [RFC4761] Kompella, K. and Y. Rekhter, "Virtual Private LAN Service
(VPLS) Using BGP for Auto-Discovery and Signaling", RFC4761, January (VPLS) Using BGP for Auto-Discovery and Signaling", RFC4761, January
2007. 2007.
[draft-ietf-idr-link-bandwidth] P. Mohapatra, R. Fernando, "BGP Link
Bandwidth Extended Community", draft-ietf-idr-link-bandwidth-06.txt
Authors' Addresses Authors' Addresses
Sami Boutros Sami Boutros
VMware, Inc. VMware, Inc.
Email: sboutros@vmware.com Email: sboutros@vmware.com
Ali Sajassi Ali Sajassi
Cisco Cisco
Email: sajassi@cisco.com Email: sajassi@cisco.com
 End of changes. 69 change blocks. 
219 lines changed or deleted 178 lines changed or added

This html diff was produced by rfcdiff 1.45. The latest version is available from http://tools.ietf.org/tools/rfcdiff/