On Wed, 2012-07-25 at 10:43 -0500, fuliang yuan wrote: > I assume that it is legit for Proxy or UAS to add R-R of other nodes in > Response based on your comments.
I am not sure exactly what you mean. The proper pattern of Record-Route header usage is: 1. The UAC generates the request without any Record-Route headers. 2. As the request passes through proxies, the proxies add Record-Route headers if they desire to do so. 3. The UAS receives the request and saves a copy of the Record-Route headers. It copies the Record-Route headers into any responses it generates. 4. The responses pass through the proxies back to the UAC. The Record-Route headers in the response are usually not modified, and in particular, no proxy adds a Record-Route to a *response* (although the response may be carrying a Record-Route header that is a copy of one that the proxy added to the *request*). 5. The UAC receives the response and saves a copy of the Record-Route headers. There are some complications: Because the actual UAs may contain "internal" proxies, the UAC may send a request that already contains Record-Route headers. Similarly, the UAS may add Record-Route headers to a request that it receives before carrying out step (3). Similarly, a proxy may add two or more (necessarily consecutive) Record-Route headers to a request during a single pass of the request through the proxy. In principle, this is modeling the proxy as a series of proxies. In some circumstances, a proxy may need to change the value of a Record-Route header in a response, when the Record-Route header is a copy of one that the proxy added to the request. This is called "Record-Route rewriting" and is discussed in RFC 3261 section 16.12.1.3. Since a request may pass through the same proxy more than once during its journey to the UAS, one proxy may add several (not necessarily consecutive) Record-Route headers to a request. To summarize: The UAS adds Record-Routes to the response, but those headers are always a copy of the Record-Routes received in the request. A proxy never adds Record-Routes to a response, although the response may contain a copy of a Record-Route that the proxy added to the request. Dale _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
