Abstract
A route advertisement carries, with the advertised prefix, an ordered sequence of underlay transport-type identifiers together with a mode indication that tells every receiving node how to resolve the route’s next hop. Each node applies the sequence in the order received and programs the highest-priority transport that is operationally available toward that next hop. Because the sequence itself travels with the route, rather than an identifier each node resolves through local configuration, a border node that rewrites the next hop to its own address and holds no routing instance for the service still reproduces that intent. One implementation encodes the sequence in a transitive extended community carried on virtual private network and Ethernet virtual private network routes, and fragments longer sequences across several instances of the community. A strict mode forbids departure from the sequence, while a loose mode permits a defined local fallback.
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Recommended Citation
Anonymous, "Signaling an Ordered Underlay Transport Preference With a Routed Prefix", Technical Disclosure Commons, ()
https://www.tdcommons.org/dpubs_series/11970