Re: M3UA AS override mode from SGP perspective
Evgenij <[email protected]>
| Newsgroups | gmane.ietf.sigtran |
|---|---|
| Message-ID | <[email protected]> |
Brian, thank you. It's explained everything. 2010/10/7 Brian F. G. Bidulock <[email protected]> > Evgenij, > > Yes, I was responsible for those passages. The SGP has little > choice but to accept messages from the previously active ASP > until it can or does react to the NOTIFY(Alternate ASP_Active). > Because the NOTIFY is not acknolwedged, the SGP cannot really > know when it is reasonable to stop accepting messages, and > therfore are typically set up to always accept them. The > passages dictate the ASP behaviour, but allow the SGP to never > discard a message. If the SGP design is so poor that it > discards messages in this case, for example, after dispatching > the Notify, then messages will be lost regardless of the ASP > behavior. This is why I say that the SGP usually accepts > messages from an ASP even when it is not active. > > --brian > > > Evgenij wrote: (Wed, 06 Oct 2010 15:56:39) > > > > Brian, I'm confused! > > > 3. In override mode only one ASP in the AS can be receiving traffic > > > (usually all can send traffic). > > Does it mean, that ASP can usually send traffic before sending ASP-AC > > message? > > The RFC4666 says: > > If the SGP or IPSP receives any Data messages before an ASP Active > > message is received, the SGP or IPSP MAY discard them. > > ... > > In the case of an Override mode AS, receipt of an ASP Active messageat > > an SGP causes the (re)direction of all traffic for the AS to the ASP > > that sent the ASP Active message. Any previously active ASP in the AS > > is now considered to be in the state ASP-INACTIVE and SHOULD no longer > > receive traffic from the SGP within the AS. The SGP or IPSP then MUST > > send a Notify message ("Alternate ASP_Active") to the previously > > active ASP in the AS and SHOULD stop traffic to/from that > > ASP. The ASP receiving this Notify MUST consider itself now in the > > ASP-INACTIVE state, if it is not already aware of this via inter-ASP > > communication with the Overriding ASP. > > I thought that data exchange in override mode is normal only for one > > ASP-SGP. > > > -- > Brian F. G. Bidulock > [email protected] > http://www.openss7.org/ > _______________________________________________ Sigtran mailing list [email protected] https://www.ietf.org/mailman/listinfo/sigtran