What vexes VoIP users?

Ok, see, now I (like, I suspect, Frank Bulk) am confused again:

when you say "which L2 channels the RTP packets were flowed onto", that
sounds to me a *whole* lot like "which VLAN on the end-user drop carried
the RTP packets from the terminal adapter in their cable box to our
concentrator"... which is pretty much the point I was originally trying
to make, if perhaps in slightly different terms.

Am I still misunderstanding you?

-- jra

They're kind of like VLAN's, but not exactly. It's been a long
time since I worked on this... The RTP is flowed over what is
called unsolicited grants (UGS) which give slots on the upstream
for transmission. There are several other types of qos treatment
between the CM and CMTS... I think that packetcable flows the
MGCP and SIP over nrt-PS, but I might be misremembering.

The signalling between the CM (MTA) and CMS (eg MGCP)
is what fields the requests for better qos treatment for the
RTP stream, and the CMS talks to the CMTS via COPS to
set up the UGS flows to the cable modem/voice box (ie,
an embedded MTA).

In any case, this is 100% IP end to end, with all kinds of
goodies for LEA and privacy to boot, which make the entire
problem of faithfully reproducing the PSTN over IP a giant

Mike, I should know about the LEA aspect since I was the
   first one at Cisco to find and then dutifully step on that mine

The service class for the bearer stream, at least on modern configurations with Moto, is "DefVoiceDown" and "DefUGS". The signaling is DefRRDown and DefRRUp.

MSOs may create different service classes with unique names, so our (plain vanilla configuration which uses the default names) may not be representative of other implementations.