I've been doing a lot reading the last few days on the advantages of "PPP over
SONET/SDH" vs "IP over ATM AAL5". The available information bandwidth of
roughly 150 Mbps out of 155.5 Mbps with STS-3c/STM-1 makes the PPP over SONET
solution very attractive. I understand that SONET facilities are widely
deployed throughout the carriers' broadband infrastructures but when will it
become practical to run packet data over these facilities? I am aware that
Cisco is planning to provide an OC-3/STM-1 interface in the 3d quarter but what
about other hardware vendors? When will carriers be ready to support this
service? Are multiplexers available or planned for the near future? Are there
carrier-to-carrier issues that need to be worked out? Any information on this
subject is very much appreciated.
Thank you.


I was thinking... as far as my limited knowledge allows..

  It seems that PPP or HDLC over OC-3 would be faster than
ATM over the same OC-3 circuit, and (at this stage) have fewer
interoperability problems.

  But you can configure PVC's with ATM, working with an ATM
cloud, similar to frame relay, no? And if this is the case, then
a large backbone-type provider may desire to set up an ATM cloud,
making it easy to add POP's (just add them to the cloud), and allow
for more layer 2 routing (just configure PVC's between every POP you
have, building a full web, and a traceroute would now travel 2 or 4
hops instead of 12...?)

  instead of some sort of hierarchichal star topology, you'd
have a large web...

  and one more potential benefit to ATM -- won't it scale
very well to OC-12? ie, when you want to upgrade your network to
OC-12, you'd have no changes to make?

  just thinkin... and I love it when y'all correct me, I tend
to learn a lot :slight_smile: