Ex Vito ha scritto:
However things seem to work configured either way. Does it make
any sense ? Well, the logs show some differences which I don't
really understand...
Yes, it make sense. Will try to go but please *do not* consider this a
bible, too complex to explain in few words.
In PMP configuration there is not a real link between the CO and user
terminal. They exchange only short frames (called RR, Receive Ready) to
know if the other end is alive [or dead :-)].
When necessary one party can initiate a link establishment procedure...
in short this end with a TEI assigned to the user terminal. The TEI
represent a unique terminal identifier value, here between 64 to 126
(like a mac address dinamically assigned on PMP).
Search google on ETSI+LAPD+ISDN+Q.920+SABME to know more.
Now a call flow can start...
In PTP configuration there is not a TEI negotiation, TEI value have
fixed 0 (zero, usually) value, link is up every time, CO and terminal
can start faster a call at any time. This also mean only a terminal can
be connected.
A misconfigured TE can work in some circustances (i.e. a PTP TE on a PMP
line) but not reliably because each party try to do illegal things or
expect somethig not true condition. Also a call setup is slightly
different on PTP versus PMP.
Sure, adequate termination is critical. But a bad enough termination would
bring L1 down first, wouldn't it ?
Not shure. Wrong termination can cause frame errors, timing errors, a/d
conversion problems, sync errors between multiple ports so errors come
up at all levels.
Anyway if you have a PMP line may be normal, telco start L2 shut down
then (a second timer expiry) shut down L1... saving $$$ on power.
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