Internet DRAFT - draft-boutros-bess-evpn-vpws-service-edge-gateway
draft-boutros-bess-evpn-vpws-service-edge-gateway
INTERNET-DRAFT Sami Boutros
Intended Status: Standard Track VMware
Patrice Brissette
Ali Sajassi
Cisco Systems
Daniel Voyer
Bell Canada
John Drake
Juniper Networks
Expires: December 31, 2017 June 29, 2017
EVPN-VPWS Service Edge Gateway
draft-boutros-bess-evpn-vpws-service-edge-gateway-04
Abstract
This document describes how a service node can dynamically terminate
EVPN virtual private wire transport service (VPWS) from access nodes
and offer Layer 2, Layer 3 and Ethernet VPN overlay services to
Customer edge devices connected to the access nodes. Service nodes
using EVPN will advertise to access nodes the L2, L3 and Ethernet VPN
overlay services it can offer for the terminated EVPN VPWS transport
service. On an access node an operator can specify the L2 or L3 or
Ethernet VPN overlay service needed by the customer edge device
connected to the access node that will be transported over the EVPN-
VPWS service between access node and service node.
Status of this Memo
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Auto-Discovery . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Scalability . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3 Head-end . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.5 Multi-homing . . . . . . . . . . . . . . . . . . . . . . . . 5
2.5 Fast Convergence . . . . . . . . . . . . . . . . . . . . . . 5
3. Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Solution Overview . . . . . . . . . . . . . . . . . . . . . . . 5
4.1 Multi-homing . . . . . . . . . . . . . . . . . . . . . . . . 7
4.2 Applicability to IP-VPN . . . . . . . . . . . . . . . . . . 8
5 Failure Scenarios . . . . . . . . . . . . . . . . . . . . . . . 8
6 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 8
7 Security Considerations . . . . . . . . . . . . . . . . . . . . 8
8 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8
9 References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1 Normative References . . . . . . . . . . . . . . . . . . . 8
9.2 Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1 Introduction
This document describes how a service node can act as a gateway
terminating dynamically EVPN virtual private wire service (VPWS) from
access nodes and offering Layer 2, EVPN and Layer 3 VPN overlay
services to Customer edge devices connected to the access nodes.
The service node would initially advertise using EVPN the different
L2, L3 and Ethernet VPN overlay services that can be transported from
access nodes over an EVPN-VPWS transport service.
The service node would advertise EVPN-VPWS per EVI Ethernet A-D
routes with the Ethernet Segment Identifier field set to 0 and the
Ethernet tag ID set to (0xFFFFFFFF wildcard), all those routes will
be associated with the EVPN-VPWS service edge RT that will be
imported by other service edge PEs, each route will have a unique RD
and will be associated with another RT corresponding to the L2, L3 or
Ethernet VPN overlay service that can be transported over the EVPN-
VPWS transport service.
The access nodes will advertise EVPN-VPWS per EVI Ethernet A-D with
the Ethernet Segment Identifier field set to 0 for single home
customer edge CE device and set to the CE's ESI and the Ethernet Tag
field is set to the VPWS service instance identifier. The route will
have a unique RD and will be associated with an RT corresponding to
the L2, L3 or Ethernet VPN overlay service that will be transported
over the EVPN-VPWS transport service.
If more than one service node advertise the ability to terminate the
EVPN-VPWS transport service and offer the L2, L3 or Ethernet VPN
service required by CE device connected to a given access node, then
all service node(s) will perform a DF election based on HWR algorithm
using {Ethernet tag-id, Service node IP addresses} to determine which
service node will be the primary service node to to terminate the
VPWS service and offer the L2, L3 or Ethernet overlay service for the
customer edge, All active and single active redundancy can be
offered.
The Service PE node that is a DF for a given VPWS service ID MUST
respond to the Eth A-D route per EVI from the access node by sending
its own Eth A-D per EVI route and by setting the same VPWS service
instance ID and downstream assigned MPLS label to be used by Access
node. When access node receives this Eth A-D route per EVI from the
service node, it binds the two side of EVCs together.
1.1 Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
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"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Requirements
This section describes the requirements specific to this draft. These
requirements are in addition to the ones described in [EVPN-REQ],
[EVPN], and [EVPN-VPWS].
2.1 Auto-Discovery
A service node needs to support the following functionality of auto-
discovery:
(R1a) A service node PE MUST be agnostic of all access nodes PEs
connected on the same access network.
(R1b) A service node PE MUST advertise its associated overlay VRF(L2
and/or L3) to all service nodes PEs connected on the same network.
(R1c) A service node PE MUST resolve received overlay VRF(L2 and/or
L3) from other service nodes with local configuration. The
information is used to select proper service node PE for a given
EVPN-VPWS connection from an access PE.
(R1d) A service node PE MUST accept EVPN-VPWS connection from any
access node PE which require one of the service node PE available L2
or L3 overlay service.
2.2 Scalability
(R2a) A single service node PE can be associated with many access
node PEs. The following requirements give a quantitative measure.
(R2b) A service node PE MUST support thousand(s) head-end connections
for a a given access node PE connecting to different overlay VRF
services on that service node.
(R2c) A service node PE MUST support thousand(s) head-end connections
to many access node PEs.
2.3 Head-end
(R3a) A service node PE MUST support L2 and/or L3 head-end
functionality.
(R3b) A service node PE SHALL support auto-configuration of L2 and/or
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L3 head-end functionality.
2.5 Multi-homing
TBD
2.5 Fast Convergence
TBD
3. Benefits
This section describes some of the major benefits of EVPN-VPWS
service edge gateway solution. This list is not considered as
exhaustive.
Majors benefits are:
- An easy and scalable mechanism for tunneling (head-end)
customer traffic into a common IP/MPLS network infra structure
- Auto-provision features such as QOS access lists (ACL), tunnel
preference, bandwidth, L3VPN on a per head-end interface basis
- reduces CAPEX in the access or aggregation network and
service PE
- Auto configuration of head-end functionality:
Configuring other Layer3 parameters, such as VRF and IP
addresses, are optional for the head-end to be
functional. However, they are required for Layer3 services
to be operational (head-end L3 termination).
- Auto-discovery of access nodes by service nodes. Hence, there
is no need to change any service node configuration when a new
access node is being added to the access network.
4. Solution Overview
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+---------+ +---------+
| | | |
+----+ +-----+ | IP/MPLS | +-----+ | IP/MPLS |
| CE |---| PE1 |-| Access |-| PE2 |-| Core |
+----+ +-----+ | Network | +-----+ | Network |
| | | |
+---------+ +---------+
<---- EVPN-VPWS ----><---- IP/MAC VRF --->
Figure 1: EVPN-VPWS Service Edge Gateway.
AN: Access node
SE: Service Edge node.
EVPN-VPWS Service Edge Gateway Operation
At the service edge node, the EVPN Per-EVI Ethernet A-D routes will
be advertised with the ESI set to 0 and the Ethernet tag-id set to
(wildcard 0xFFFFFFF). The Ethernet A-D routes will have a unique RD
and will be associated with 2 BGP RT(s), one RT corresponding to the
underlay EVI i.e. the EVPN VPWS transport service that's configured
only among the service edge nodes, and one corresponding to the L2,
L3 or EVPN overlay service.
At the access nodes, the EVPN per-EVI Ethernet A-D routes will be
advertised as described in [draft-ietf-bess-evpn-vpws] with the ESI
field is set to 0 and for single homed CEs and to the CE's ESI for
multi-homed CE's and the Ethernet Tag field will be set to the VPWS
service instance identifier that identifies the EVPL or EPL service.
The Ethernet-AD route will have a unique RD and will be associated
with one BGP RT corresponding to the L2, L3 or EVPN overlay service
that will be transported over this EVPN VPWS transport service.
Service edge nodes on the underlay EVI will determine the primary
service node terminating the VPWS transport service and offering the
L2, L3 or Ethernet VPN service by running the on HWR algorithm as
described in [draft-mohanty-l2vpn-evpn-df-election] using weight
[VPWS service identifier, Service Edge Node IP address]. This ensure
that service node(s) will consistently pick the primary service node
even after service node failure. Upon primary service node failure,
all other remaining services nodes will choose another service node
correctly and consistently.
Single-sided signaling mechanism is used. The Service PE node that is
a DF for accepts to terminate the VPWS transport service from an
access node, the primary service edge node shall:- Dynamically create
an interface to terminate the service and shall attach this interface
to the overlay VPN service required by the access node to service its
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customer edge device.- Responds to the Eth A-D route per EVI from the
access node by sending its own Eth A-D per EVI route by setting the
same VPWS service instance ID and downstream assigned MPLS label to
be used by the access node.
When access node receives this Eth A-D route per EVI from the service
edge node, it binds the two side of EVCs together and it now knows
what primary/backup service nodes to forward the traffic to.
The service edge node shall support per features such as QoS, ACL,
etc. for the EVPN VPWS transport service it terminates.
4.1 Multi-homing
+---------+ +---------+
+----+ +-----+ | | +-----+ | |
| CE |---| AN1 |-| |-| SE2 |-| |
+----+ +-----+ | IP/MPLS | +-----+ | IP/MPLS |
| Access | | Core |
| Network | +-----+ | Network |
| |-| SE3 |-| |
| | +-----+ | |
+---------+ +---------+
<---- EVPN-VPWS ----><---- IP/MAC VRF --->
Figure 2: EVPN-VPWS SEG Multi-homing (same ASN)
AN: Access node
SE: Service Edge node.
+---------+ +---------+
+----+ +-----+ | | +-----+ | ASN-A |
| CE |---| AN1 |-| |-| SE2 |-| Core |
+----+ +-----+ | IP/MPLS | +-----+ | Network |
| Access | +---------+
| Network | +---------+
| | +-----+ | ASN-B |
| |-| SE3 |-| Core |
| | +-----+ | Network |
+---------+ +---------+
<---- EVPN-VPWS ----><---- IP/MAC VRF --->
Figure 3: EVPN-VPWS SEG Multi-homing (different ASN)
AN: Access node
SE: Service Edge node.
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Both All-active and single active redundancy can be supported.
A backup service node can be preprogrammed in data plane on an access
node in order to switch traffic and based on how fast the data plane
detect the failure of the primary service node traffic on an access
node can switch to the backup node.
4.2 Applicability to IP-VPN TBD
5 Failure Scenarios TBD
6 Acknowledgements TBD.
7 Security Considerations
This document does not introduce any additional security constraints.
8 IANA Considerations
TBD.
9 References
9.1 Normative References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
9.2 Informative References
[RFC7209] A. Sajassi, R. Aggarwal et. al., "Requirements for Ethernet
VPN".
[EVPN] A. Sajassi, R. Aggarwal et. al., "BGP MPLS Based Ethernet
VPN", draft-ietf-l2vpn-evpn-11.txt.
[EVPN-VPWS] S. Boutros et. al., "EVPN-VPWS", draft-ietf-bess-evpn-
vpws-00.txt.
Authors' Addresses
Sami Boutros
VMware, Inc.
Email: sboutros@vmware.com
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Patrice Brissette
Cisco
Email: pbrisset@cisco.com
Ali Sajassi
Cisco
Email: sajassi@cisco.com
Daniel Voyer
Bell Canada
Email: daniel.voyer@bell.ca
John Drake
Juniper Networks
Email: jdrake@juniper.net
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