L2VPN over SR-TE Preferred Path

Table 1. Feature History

Feature Name

Release Information

Description

L2VPN Traffic Steering Using SR-TE Preferred Path with Flexible Algorithm

 Cisco IOS XE Bengaluru 17.6.1

This feature allows you to configure an SR policy with as the preferred path for a VPWS or VPLS pseudowire, with Flexible Algorithm. VPWS or VPLS pseudowires between same PEs can be routed over different SR policies based on the requirements. Prior to this release, you could only steer the traffic using the SR policy for routing IPv4 traffic to a destination pseudowire (over IGP or BGP-LU).

Virtual Private LAN Services (VPLS) enables enterprises to link together multiple Ethernet-based LANs via the infrastructure provided by their service provider.

VPLS uses the service provider core to join multiple attachment circuits of an enterprise to simulate a virtual bridge. From the enterprise point of view, there is no topology for VPLS. All customer edge (CE) devices appear to connect to a logical bridge emulated by the service provider core.

Prior to Cisco IOS XE Bengaluru Release 17.6.1, L2VPN (VPLS or VPWS) traffic over SR policies could not be steered. You could only steer IPv4 traffic using the SR policy for routing IPv4 traffic to a destination pseudowire (over IGP or BGP-LU).

Now you configure an SR policy as the preferred path for a VPWS or VPLS pseudowire, with Flexible Algorithm. VPWS or VPLS pseudowires between same PEs can also be routed over different SR policies.

Disable Fallback Option

The disable fallback option disables the router from using the default path when the preferred path SR policy goes down.

Restrictions

  • You cannot add On-Demand (ODN) policies to the preferred path.

  • L2VPN over SR-TE preferred path is only supported on SR Per Destination Policy (PDP); and not on the SR Per-Flow Policy (PFP).

  • L2VPN over SR-TE preferred path can only be configured using the pseudowire interface.

  • This feature is supported only on IS-IS protocol

Configuring L2VPN Traffic Steering Using SR-TE Preferred Path with Flexible Algorithm

To configure IS-IS with Flex Algo:
router isis 1

affinity-map green bit-position 0
affinity-map red bit-position 1
affinity-map yello bit-position 2
flex-algo 128
  advertise-definition
  metric-type delay
  priority 200
  affinity
   exclude-any
    name red
    name yellow
!
flex-algo 129
  advertise-definition
  priority 200
  affinity
   exclude-any
    name green
    name red
 
 
 
interface Tunnel100
isis affinity flex-algo
  name green
  !
interface Tunnel101
isis affinity flex-algo
  name yellow
 !
interface Tunnel102
isis affinity flex-algo
  name red
 
 
 
segment-routing traffic-eng  
 policy p-2000
  color 2000 end-point 10.4.4.4
  performance-measurement
   delay-measurement
  candidate-paths
   preference 10
    constraints
     segments
      dataplane mpls
      algorithm 128
     !
     !
    !
    dynamic
To create SR static policy for MPLS label:
configure terminal segment-routing traffic-eng 
segment-list name segment-name 
index 1 mpls label first hop label 
index 2 mpls label second hop label ! 
policy policy-name 
color color-code end-point destination IP Address candidate-paths 
preference preference 
explicit segment-list segment-name 
constraints 
segments dataplane mpls
You can also create SR static policy for the following:

  • MPLS adjacency

  • MPLS prefix

L2VPN over SR-TE preferred path can be configured in the following ways:

  • Non-Template based Configuration

  • Template-based Configuration

Non-template Based Configuration:

  • Create Pseudowire

    To create pseudowire:
    interface pseudowire 1
 encapsulation mpls
 neighbor peer-address vc-id

  • Attach Policy Using Preferred Path

    To attach a policy using the preferred path:
    interface pseudowire1
 preferred-path segment-routing traffic-eng policy policy-name [disable-fallback]
Template-based Configuration:

  • Create Template Type Pseudowire

    To create template type pseudowire:
    template type pseudowire name
 encapsulation mpls
 preferred-path segment-routing traffic-eng policy name [disable-fallback]

  • Attach Policy Using Preferred Path

    To attach a policy using the preferred path:
    interface pseudowire 1
 source template type pseudowire name

Configuration Example 1: VPWS Psuedowire over SR-TE Preferred Path

! 
interface 
gi0/0/1 
service instance 1000 
ethernet encapsulation 
dot1q 1000 ! 
template type pseudowire l2vpntest
 encapsulation mpls 
preferred-path Segment-Routing traffic-eng policy p106 
l2vpn xconnect context l2vpn-test 
member 10.6.6.6 1000 template 
l2vpntest member gi0/0/1 
service-instance 1000  !

Configuration Example 2: VPWS Psuedowire over SR-TE Preferred Path

! 
! 
interface gi0/0/1 
service instance 1000 ethernet
 encapsulation dot1q 1000
 ! 
template type pseudowire 
l2vpntest encapsulation mpls 
preferred-path Segment-Routing traffic-eng policy p106 ! 

interface pseudowire1000 
 source template type pseudowire l2vpntest  
encapsulation mpls  neighbor 10.1.1.1 1000 ! 

l2vpn xconnect context l2vpn-test  
member pseudowire 1000 
 member gi0/0/1 service-instance 1000

Configuration Example 3: VPLS Psuedowire over SR-TE Preferred Path

interface gi0/0/1 

service instance 1000 
ethernet   encapsulation 
dot1q 1000 ! 

interface pseudowire106  
encapsulation mpls 
 neighbor 10.6.6.6 1000 

 preferred-path Segment-Routing traffic-eng policy p106 ! 
interface pseudowire104
 encapsulation mpls
  neighbor 10.4.4.4 1000
 
preferred-path Segment-Routing traffic-eng policy p104
 ! 
l2vpn vfi context VC_1000   vpn id 1000  member
 pseudowire106  member pseudowire104 
! 

bridge-domain 1000
 
member gi0/0/1 service-instance
 1000 member vfi VC_1000

Verification of L2VPN over SR-TE Preferred Path Configuration

Use the show segment-routing traffic-eng policy name policy name detail command to verify the policy configuration:
Router#show segment-routing traffic-eng policy name CE11-PE12 detail
 
Name: CE11-PE12 (Color: 50 End-point: 10.12.12.12)
  Owners : CLI
  Status:
    Admin: up, Operational: up for 70:04:00 (since 08-17 07:55:36.536)
  Candidate-paths:
    Preference 100 (CLI):
      Explicit: segment-list IntraDomain (active)
        Weight: 1, Metric Type: TE
16005
16008
16010
Attributes:
    Binding SID: 20
      Allocation mode: dynamic
      State: Programmed
  Tunnel ID: 65538 (Interface Handle: 0x20)
  Per owner configs:
    CLI
      Binding SID: dynamic
  Stats:
    Packets: 0  Bytes: 0
 
  Event history:
    Timestamp                   Client                  Event type              Context: Value
    ----------------            ------                  --------------               ---------: ---------
    10-28 04:05:37.028          L2VPN                   Policy created           Name: L2VPN
    10-28 04:05:37.048          L2VPN                   BSID allocated           FWD: label 20
    10-28 04:05:37.494          L2VPN                   Client removed           Owner: Destroyed
    10-28 04:05:37.494          CLI                      Set colour                  Colour: 230
    10-28 04:05:37.494          CLI                      Set end point            End-point: 12.12.12.12
    10-28 04:05:37.496          CLI                     Set explicit path       Path option: IntraDomain
    10-28 04:08:22.873          FH Resolution           Policy state UP         Status: PATH RESOLVED
    10-28 04:08:45.630          FH Resolution           REOPT triggered         Status: REOPTIMIZED
Use show mpls l2transport vc 1000 detail command to verify the L2VPN over SR-TE preferred path:
Router#show mpls l2transport vc 1000 detail
Local interface: VFI VC_1000 vfi up
  Interworking type is Ethernet
  Destination address: 10.12.12.12, VC ID: 1000, VC status: up
    Output interface: tu65538, imposed label stack {16005 16008 16010 32}
    Preferred path: not configured  
    Default path: active
    Next hop: 10.168.1.1
  Create time: 1w4d, last status change time: 22:50:57
    Last label FSM state change time: 22:51:46
  Signaling protocol: LDP, peer 10.1.1.1:0 up
    Targeted Hello: 10.2.2.2(LDP Id) -> 10.1.1.1, LDP is UP
    Graceful restart: not configured and not enabled
    Non stop routing: not configured and not enabled
    Status TLV support (local/remote)   : enabled/supported
      LDP route watch                   : enabled
      Label/status state machine        : established, LruRru
      Last local dataplane   status rcvd: No fault
      Last BFD dataplane     status rcvd: Not sent
      Last BFD peer monitor  status rcvd: No fault
      Last local AC  circuit status rcvd: No fault
      Last local AC  circuit status sent: No fault
      Last local PW i/f circ status rcvd: No fault
      Last local LDP TLV     status sent: No fault
      Last remote LDP TLV    status rcvd: No fault
      Last remote LDP ADJ    status rcvd: No fault
    MPLS VC labels: local 26, remote 21
    Group ID: local n/a, remote 16
    MTU: local 9000, remote 9000
    Remote interface description:
    MAC Withdraw: sent:0, received:301
  Sequencing: receive disabled, send disabled
  Control Word: On (configured: autosense