< draft-boutros-l2vpn-evpn-vpws-03.txt   draft-boutros-l2vpn-evpn-vpws-04.txt >
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Cisco Systems Cisco Systems
John Drake John Drake
Juniper Networks Juniper Networks
Jeff Tantsura Jeff Tantsura
Ericsson Ericsson
Dirk Steinberg Dirk Steinberg
Steinberg Consulting Steinberg Consulting
Expires: August 18, 2014 February 14, 2014
Thomas Beckhaus
Deutsche Telecom
Expires: January 3, 2015 July 2, 2014
VPWS support in E-VPN VPWS support in E-VPN
draft-boutros-l2vpn-evpn-vpws-03.txt draft-boutros-l2vpn-evpn-vpws-04.txt
Abstract Abstract
This document describes how E-VPN can be used to support virtual This document describes how E-VPN can be used to support virtual
private wire service (VPWS) in MPLS/IP networks. E-VPN enables the private wire service (VPWS) in MPLS/IP networks. E-VPN 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 single-segment and multi-segment PW signaling, and provides
fast protection using data-plane prefix independent convergence upon fast protection using data-plane prefix independent convergence upon
node or link failure. node or link failure.
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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 . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Requirements . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2 Requirements . . . . . . . . . . . . . . . . . . . . . . . . 4
2. BGP Extensions . . . . . . . . . . . . . . . . . . . . . . . . 5 2. BGP Extensions . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 EVPN Comparison to PW Signaling . . . . . . . . . . . . . . . . 6 4 EVPN Comparison to PW Signaling . . . . . . . . . . . . . . . . 7
5 ESI Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . 7 5 ESI Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . 7
6 ESI value derivation and Eth-tag setting . . . . . . . . . . . . 7
7 VPWS with multiple sites . . . . . . . . . . . . . . . . . . . . 8 7 VPWS with multiple sites . . . . . . . . . . . . . . . . . . . . 8
8 Security Considerations . . . . . . . . . . . . . . . . . . . . 8 8 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 8
9 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8 9 Security Considerations . . . . . . . . . . . . . . . . . . . . 8
10 References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 10 IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
10.1 Normative References . . . . . . . . . . . . . . . . . . . 8 11 References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
10.2 Informative References . . . . . . . . . . . . . . . . . . 8 11.1 Normative References . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 11.2 Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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 signaling single-segment and
multi-segment PWs for p2p Ethernet services. multi-segment PWs for p2p Ethernet services.
[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), aka Ethernet Segment in EVPN
terminology, without any MAC lookup. This capability is ideal in terminology, without any MAC lookup. This capability is ideal in
providing p2p services (aka VPWS services). [MEF] defines Ethernet providing p2p services (aka VPWS services). [MEF] defines Ethernet
Virtual Private Line (EVPL) service as p2p service between a pair of Virtual Private Line (EVPL) service as p2p service between a pair of
ACs (designated by VLANs). EVPL can be considered as a VPWS with only ACs (designated by VLANs) and Ethernet Private Line (EPL) service, in
two ACs. In delivering an EVPL service, the traffic forwarding which all traffic flows are between a single pair of ESes. EVPL can
capability of EVPN based on the exchange of a pair of Ethernet AD be considered as a VPWS with only two ACs. In delivering an EVPL
routes is used; whereas, for more general VPWS, traffic forwarding service, the traffic forwarding capability of EVPN based on the
capability of EVPN based on the exchange of a group of Ethernet AD exchange of a pair of Ethernet AD routes is used; whereas, for more
routes (one Ethernet AD route per AC/segment) is used. In a VPWS general VPWS, traffic forwarding capability of EVPN based on the
service, the traffic from an originating Ethernet Segment can be exchange of a group of Ethernet AD routes (one Ethernet AD route per
forwarded only to a single destination Ethernet Segment; hence, no AC/segment) is used. In a VPWS service, the traffic from an
MAC lookup is needed and the MPLS label associated with the per-EVI originating Ethernet Segment can be forwarded only to a single
Ethernet AD route can be used in forwarding user traffic to the destination Ethernet Segment; hence, no MAC lookup is needed and the
destination AC. MPLS label associated with the per-EVI Ethernet AD route can be used
in forwarding user traffic to the destination AC.
In current PW redundancy mechanisms, convergence time is a function Both services are supported by using the Per EVI Ethernet AD route
of control plane convergence characteristics. However, with EVPN it which contains an Ethernet Segment Identifier, in which the customer
is possible to attain faster convergence through the use of data- ES is encoded, and an Ethernet Tag, in which the VPWS service
plane prefix independent convergence, upon node or link failure. instance identifier is encoded. I.e., for both EPL and EVPL
services, a specific VPWS service instance is identified by a pair of
Per EVI Ethernet AD routes which together identify the VPWS service
instance endpoints and the VPWS service instance. In the control
plane the VPWS service instance is identified using the VPWS service
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 it
traffic for that VPWS service instance. As with the Ethernet Tag in
standard EVPN, the VPWS service instance identifier has uniqueness
within an EVPN instance. The Ethernet Segment identifier encoded in
he per EVI Ethernet AD route is not used to identify the service,
however it can be used for flow-based load-balancing and mass
withdraw functions.
This document proposes the use of the Ethernet AD route to signal As with standard EVPN, the Per ES Ethernet AD route is used for fast
labels for P2P Ethernet services. As with EVPN, the Ethernet Segment convergence upon link or node failure and the Ethernet Segment route
route can be used to synchronize state between the PEs attached to is used for auto-discovery of the PEs attached to a given multi-homed
the same multi-homed Ethernet Segment. CE and to synchronize state between them.
1.1 Terminology 1.1 Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
MAC: Media Access Control MAC: Media Access Control
MPLS: Multi Protocol Label Switching. MPLS: Multi Protocol Label Switching.
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other VLANs on the trunk. Other VLANs on the same trunk could also be other VLANs on the trunk. Other VLANs on the same trunk could also be
used for EVPL services, but could also be associated with other used for EVPL services, but could also be associated with other
services. 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 access trunk could have hundreds of EVPL services, and 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.
2. BGP Extensions 2. BGP Extensions
[EVPN] defines a new BGP NLRI for advertising different route types This document proposes the use of the Per EVI Ethernet AD route to
for EVPN operation. This document does not define any new BGP signal VPWS services. The Ethernet Segment Identifier field is set to
messages, but rather re-purposes one of the routes as described next. the customer ES and the Ethernet Tag field is set to the VPWS service
instance identifier. For both EPL and EVPL services, for a given
VPWS service instance the pair of PEs instantiating that VPWS service
instance will each advertise a Per EVI Ethernet AD route with its
VPWS service instance identifier and will each be configured with the
other PE's VPWS service instance identifier. When each PE has
received the other PE's
This document proposes the use of the per EVI Ethernet AD route to Per EVI Ethernet AD route the VPWS service instance is instantiated.
signal P2P services. The Ethernet Segment Identifier field is set to It should be noted that the same VPWS service instance identifier may
the ESI of the attachment circuit of the VPWS service instance. The be configured on both PEs.
Ethernet Tag field is set to 0 in the case of an Ethernet Private
Wire service, and to the VLAN identifier associated with the service The Route-Target (RT) extended community with which the Per EVI
for Ethernet Virtual Private Wire service. The Route-Target (RT) Ethernet AD route is tagged identifies the EVPN instance in which the
extended community that identifies the VPN associated with the p2p VPWS service instance is configured. It is the operator's choice as
EVPLs where each EVPL is identified by <ESI,Eth tag>. to how many and which VPWS service instances are configured in a
given EVPN instance. However, a given EVPN instance MUST NOT be
configured with both VPWS service instances and standard EVPN multi-
point services.
3 Operation 3 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 |
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| | | | | |
| 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 EVPN All PEs and ASBRs are enabled for the EVPN SAFI and exchange Per EVI
Ethernet A-D routes - one route per AC. The ASBRs re-advertise the Ethernet AD routes, one route per VPWS service instance. For inter-
Ethernet A-D routes with Next Hop attribute set to their IP AS option B, the ASBRs re-advertise these routes with Next Hop
addresses. The link between the CE and the PE is either a C-tagged or attribute set to their IP addresses. The link between the CE and the
S-tagged interface, as described in [802.1Q], that can carry a single PE is either a C-tagged or S-tagged interface, as described in
VLAN tag or two nested VLAN tags. This interface is set up as a trunk [802.1Q], that can carry a single VLAN tag or two nested VLAN tags
with multiple VLANs. 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
A VPWS with multiple sites or multiple EVPL services on the same CE customer at either end of a VPWS service instance to identify that
port can be included in one EVI between 2 or more PEs. An Ethernet service instance may be different and EVPN doesn't perform that
Tag corresponding to each P2P connection and known to both PEs is translation between the two values. Rather, this should be done by
used to identify the services multiplexed in the same EVI. the Ethernet interface.
For CE single-homing the ESI field must be set to 0 in the Ethernet
AD route, the <Eth-tag> field will be set to the AC-ID of the EVPL or
EPL service.
For CE multi-homing, the Ethernet AD Route encodes the ESI associated
with the CE. This allows flow-based load-balancing of traffic between
PEs connected to the same multi-homed CE. The AC ID encoded in the
tag field MUST be the same on both PEs attached to the site. The
Ethernet Segment route may be used too, for discovery of multi-homed
CEs. In all cases traffic follows the transport paths, which may be
asymmetric.
The <Eth-tag> field of the EVI EAD route represents the AC-ID of the
EPL and EVPL service.
EPL service need to be identified by a non 0 <Eth-tag> field in the For single-homed CE, in an advertised Per EVI Ethernet AD route the
Ethernet AD route. 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.
The <Eth-tag> field value representing the AC-ID of the EPL/EVPL For a multi-homed CE, in an advertised Per EVI Ethernet AD route the
service of the remote side may be equal to the local side. 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
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
to that ES. In all cases traffic follows the transport paths, which
may be asymmetric.
An operator may choose to associate many per EVI EAD routes with The VPWS service instance identifier encoded in the Ethernet Tag
different ESIs and tags to the same Route-Target (RT) extended field in an advertised Per EVI Ethernet AD route MUST either be
community attribute. As such, the association of per EVI EAD routes unique across all ASs, or an ASBR needs to perform a translation when
to the same RT is a network operator design choice. the per EVI Ethernet AD route is re-advertised by the ASBR from one
AS to the other AS.
Per ES EAD route can be used for mass withdraw to withdraw all per Per ES EAD route can be used for mass withdraw to withdraw all per
EVI EAD routes associated with the multi-home site on a given PE. EVI EAD routes associated with the multi-home site on a given PE.
The VLANs on the two ACs of a given EVPL service may have different
VLANs. EVPN doesn't perform that translation, and that it should be
handled by the Ethernet interface.
4 EVPN Comparison to PW Signaling 4 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
is limited to single-active mode, while with EVPN implementation of is limited to single-active mode, while with EVPN implementation of
VPWS both single-active and all-active redundancy modes can be VPWS both single-active and all-active redundancy modes can be
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for the Bandwidth requested by this EVPL service. for the Bandwidth requested by this EVPL service.
In the case where PSN resources are not available, the PE receiving In the case where PSN resources are not available, the PE receiving
this attribute MUST re-send its local Ethernet AD routes for this this attribute MUST re-send its local Ethernet AD routes for this
EVPL service with the ESI Bandwidth = All FFs to declare that the EVPL service with the ESI Bandwidth = All FFs to declare that the
"PSN Resources Unavailable". "PSN Resources Unavailable".
The scope of the ESI Bandwidth is limited to only one Autonomous The scope of the ESI Bandwidth is limited to only one Autonomous
System. System.
6 ESI value derivation and Eth-tag setting
The ESI value is set per [EVPN] procedures - e.g., it is set to 0
for single home sites and can be manually configured or auto-derived
for multi-homed sites.
The <Eth-tag> field in the Ethernet A-D per EVI route is set to the
AC-ID representing the EPL or EVPL service. This is different from
the baseline [EVPN] Where <Eth-tag> field is set only for VLAN-aware
bundle service.
The AC-ID value SHOULD be the same at both sides of the EPL or EVPL
service and it SHOULD be unique within an AS.
"EVI" for VPWS services MUST be different from multipoint services
specified in baseline [EVPN]. This implies the corresponding RTs for
VPWS and multipoint services needs to be different.
AC-IDs in the <Eth-tag> field MUST be unique within one AS, an ASBR
MAY be required to perform AC-IDs translations if the AC-IDs are not
unique across multiple ASs.
Local and remote AC-IDs of a given EVPL or EPL service, are
configured by an operator to connect the 2 sides of the EPL/EVPL
services at both sides of the services.
7 VPWS with multiple sites 7 VPWS with multiple sites
The VPWS among multiple sites (full mesh of P2P connections - one per The VPWS among multiple sites (full mesh of P2P connections - one per
pair of sites) that can be setup automatically without any explicit pair of sites) that can be setup automatically without any explicit
provisioning of P2P connections among the sites is outside the scope provisioning of P2P connections among the sites is outside the scope
of this document. of this document.
8 Security Considerations 8 Acknowledgements
The authors would like to acknowledge Wen Lin contributions to this
document.
9 Security Considerations
This document does not introduce any additional security constraints. This document does not introduce any additional security constraints.
9 IANA Considerations 10 IANA Considerations
TBD TBD.
10 References 11 References
10.1 Normative References 11.1 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.
10.2 Informative References 11.2 Informative References
[EVPN-REQ] A. Sajassi, R. Aggarwal et. al., "Requirements for [EVPN-REQ] A. Sajassi, R. Aggarwal et. al., "Requirements for
Ethernet VPN", draft-ietf-l2vpn-evpn-req-00.txt. Ethernet VPN", draft-ietf-l2vpn-evpn-req-00.txt.
[EVPN] A. Sajassi, R. Aggarwal et. al., "BGP MPLS Based Ethernet [EVPN] A. Sajassi, R. Aggarwal et. al., "BGP MPLS Based Ethernet
VPN", draft-ietf-l2vpn-evpn-04.txt. VPN", draft-ietf-l2vpn-evpn-04.txt.
[PBB-EVPN] A. Sajassi et. al., "PBB-EVPN", draft-ietf-l2vpn-pbb-evpn- [PBB-EVPN] A. Sajassi et. al., "PBB-EVPN", draft-ietf-l2vpn-pbb-evpn-
05.txt. 05.txt.
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Ericsson Ericsson
Email: jeff.tantsura@ericsson.com Email: jeff.tantsura@ericsson.com
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
Deutsche Telecom
Email:Thomas.Beckhaus@telekom.de>
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