SDP binding

To configure a distributed service pointing from NOK-A to NOK-B, the SDP ID on the NOK-A side (see SDP tunnel pointing from NOK-A to NOK-B) must be specified during service creation in order to bind the service to the tunnel (the SDP). Otherwise, service traffic is not directed to a far-end point and the far-end devices cannot participate in the service (there is no service). To configure a distributed service pointing from NOK-B to NOK-A, a return SDP on the NOK-B side must similarly be specified.

Figure 1. SDP tunnel pointing from NOK-A to NOK-B

SDP configuration and binding is required for:

  • Layer 2 services that use T-LDP signaling

  • Layer 3 services that do not use multi-protocol BGP(MP-BGP) to advertise routes with auto-bind

For Layer 3 VPRN services that use MP-BGP to advertise routes, auto-bind can be configured on the service to automatically bind that service to SDPs with reachability to remote nodes that are participating in MP-BGP.

The VPRN auto-bind function has the following characteristics.

  • SDPs can be configured while auto-bind is enabled.

  • Configuring SDPs when auto-bind is enabled is not required to transport VPRN services between nodes participating in the same VPRN.

  • Configured SDPs have higher precedence and the node will select the configured SDP and its attributes to tunnel traffic to the far-end node.

  • Auto-bind does not require a return path SDP from a far-end router as long as auto-bind is enabled on that far-end router for the service. If auto-bind is not enabled on the far-end router, then a return path SDP to the local 7705 SAR-Hm series node is required.

  • For Layer 2 services that use BGP signaling (BGP-VPLS and BGP-VPWS) to exchange label information for the service, auto-gre can be configured on the pseudowire template of the service to automatically bind that service to SDPs with reachability to remote nodes that are participating in the BGP-signaled Layer 2 service. For information about the auto-GRE function available for BGP-VPLS and BGP-VPWS, see the 7450 ESS, 7750 SR, 7950 XRS, and VSR Layer 2 Services and EVPN Guide.