BGP VPWS with inter-AS model C is supported both in a single-homed and dual-homed configuration.
When dual-homing is used, the dual-homed PEs must have different values configured for the site-preference (under the site within the Epipe service) to allow the PEs in a different AS to select the designated forwarder when all access circuits are up. The value configured for the site-preference is propagated between autonomous systems in the BGP VPWS and BGP multi-homing update extended community VPLS preference field. The receiving ingress ASBR copies the VPLS preference value into local preference of the update to ensure that the VPLS preference and local preference are equal, which prevents the update from being considered malformed.