What should an SBC do when it resolves registered contacts?

[hkaplan@…]

In many deployments, SBC's perform a registration caching model, whereby they have a local registration cache which is used to replace request-uri's for routing to endpoints. The UA registers to the SBC using contact URI X, and the SBC sends contact URI Y to the full Registrar; so when a request to Y comes to the SBC, it replaces it with X.

Under that model, do we expect the SBC to add an H-I of type "rc"? If so, for the same fork branch, there will be two "rc" entries, one for Y and one for X. (if the SBC doesn't simply remove the Y entry)

Therefore, I think there should be some text to make it clear that receiving a H-I list with multiple "rc" entries for the same branch tree is ok. For example, receiving a index 1.1 of "rc" followed by a 1.1.1 of "rc", and maybe even a 1.1.1.1 of "rc".