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Cell Relay Retreat>List Archive>month:1997-Nov> msg00139



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Re: ATM over SDH

  • From: rajeev@trillium.com (Rajeev Gupta)
  • Date: 20 Nov 1997 00:31:46 GMT


> From: Carl Symborski <carl@umd5.umd.edu>
> > Can somebody tell the use of setting the path signal label in an SDH path
> > to 13. That is the number so SDH knows that he is transporting ATM cells?
> > 
> > What use is it that SDH knows that the payload is ATM?

If you view SONET as a multiplexing layer that can carry payload from
different protocols, then the receiver of a SONET frame must be
able to verify the payload protocol. This is no different from
the protocol id field in Ethernet frames.

> I presume there are other mappings.  Anyone know how IP is directly mapped
> onto SONET?

IP is mapped onto SONET using PPP framing.  RFC 1619 states that the
experimental value of 207 (CF hex) is used to indicate that the contents
of the SPE are PPP frames.

______________________________________________________________________
Rajeev Gupta                            Trillium Digital Systems, Inc.
mailto:rajeev@trillium.com                     http://www.trillium.com