BTW, the vast majority of SONET/SDH equipments achieve sub-50ms path protection switching. (Requirement in BellCore/Telcordia states that SONET equipment must detect a failure within 10ms and perform protection switching in no more than 50ms.) Also, the mechanisms by which fast restoral happens in MPLS are usually tied to SONET/SDH signals like:LOS (Loss Of Signal) and SD/SF (Signal Degrade/Signal Fail). cheers. jld. Alan Hannan <alan@globalcenter.net> on 10/14/99 07:27:06 PM To: Bulent Yener <yener@research.bell-labs.com> cc: nanog@merit.edu (bcc: Jeanlou Dupont/RMQ/RELTECCORP) Subject: Re: IP-Internets 3 bits of clarification:

Some stick MPLS in the middle ala IP/MPLS/HDLC or IP/MPLS/SONET.

This was dumb. I meant, ala IP/MPLS/HDLC or IP/MPLS/PPP. A couple of folks mailed me to state that MPLS as a transport technology was in the future, isn't it? In fact, 2 networks including our own have deployed large [mostly ubiquitous] MPLS deployments, where most traffic runs on it, one all over, another in certain regions/areas. Finally, I was 'reminded' that MPLS convergence will actually surpass SONET w/ restoral times, on the order of << 50 ms. Really real soon now. -alan