Also, the 2xx and the NOTIFY may not follow the exact same path: 2xx traverses all nodes that the SUBSCRIBE traversed whereas the NOTIFY will only need to traverse the subset of proxies that record-routed the SUBSCRIBE. Hence, the NOTIFY may very well arive at the UAC before the 2xx even without packets being dropped or reordered.
Anders Paul Kyzivat wrote: > Even if the NOTIFY is sent after the 2xx (SUBSCRIBE) it may arrive > first. And in the case if forking it may arrive without ever receiving a > 2xx. So the subscriber must be prepared to receive it first. Once you > realize that, there is little point in restricting the notifier to send > the 2xx first. I suspect in some implementations these may be handled > asynchronously, and so the order of sending may be indeterminate. I see > no reason to force the implementation to synchronize them. > > Thanks, > Paul > > Rockson Li (zhengyli) wrote: >> Hi folks, >> >> I think the first NOTIFY message should be sent after 2xx(SUBSCRIBE). >> This is described in RFC3265 sec3.1.6.2 >> >> >> Note that a NOTIFY message is always sent immediately after any 200- >> class response to a SUBSCRIBE request, regardless of whether the >> subscription has already been authorized. >> >> >> But why in RFC5057 Figure 3, both F1 and F2 are sent before >> 200(SUBSCRIBE)? >> >> thanks >> >> -Rockson >> _______________________________________________ >> Sip-implementors mailing list >> [email protected] >> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors >> > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
