BearerCaps IE for call-independent signalling Setup message

Miner Gleason mgleason at CISCO.COM
Mon Apr 15 15:41:28 EDT 2002


Dear experts,

I'd like to check my interpretation of the format of the BearerCaps IE
for a Setup message for call-independent signalling connections.  Per
H.225.0 7.2.2.1:  "If this information element appears in a Setup
message for a call-independent signalling connection as defined in
Recommendation H.450.1, the coding shall follow 7.2/H.450.1."

Normally this IE will have octets 3, 4, and 5, and if multirate, also
octet 4.1, for length of either 5 or 6 octets.  But for the signalling
only connection, 7.2/H.450.1 states:  "...the coding defined in Q.931
shall apply for octets 1 to 2 and bit 8 of octets 3 to 4. Information
transfer capability, Transfer mode and Information transfer rate shall
be encoded as indicated and no other octets shall be included."  So for
this case we have only octets 1 to 4, with a length therefore of 4
octets.  Taking this with the bit 8 coding from Q.931, it appears that
for the signalling case the BearerCaps IE should contain octets 3 and 4
with values:

  3: 0xA8
  4: 0x80

Does this seem correct?

--
best regards,
miner
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   Miner Gleason, Software Engineer   |       |         |
          mgleason at cisco.com          |      :|:       :|:
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