MPLS-Enabled Applications: Emerging Developments and New Technologies

12.6. LDP AND BGP INTERWORKING FOR VPLS

In earlier sections, we have discussed LDP-based and BGP-based signaling schemes for VPLS. Sometimes there is a need for interworking between these schemes. One example is where a service provider has some PE equipment which only supports LDP signaling for VPLS, which makes it impossible to deploy BGP signaling everywhere.

Let us look at the network in Figure 12.13 as an example. The grey region contains routers that support only LDP signaling for VPLS. The region in white contains routers that support BGP signaling and autodiscovery for VPLS. Router A in the white region supports both BGP and LDP signaling for VPLS. Two customers are shown, customer J whose CE devices are labeled J1, J2, etc. and customer K whose CE devices are labeled K1, K2, etc. As can be seen, both J and K have some sites that are attached to the LDP-VPLS region and others that are attached to the BGP-VPLS region.

Figure 12.13. Network diagram for LDP-BGP VPLS interworking discussion: one LDP domain and one BGP domain

One method to achieve interworking between the two domains is as follows [INTER]. The equipment in the grey domain simply runs standard LDP-based VPLS signaling. Router A performs an interworking function between the BGP and the LDP domains. The scheme has the following properties:

• No changes are required to the BGP or LDP signaling mechanisms

• From the ...