MGCP PRI in spoof mode and RTMT alears

Unanswered Question
Aug 1st, 2008

I just found out that one of my redundant PRIs is in spoof mode but I did not get a rtmt alert. Since it is redundant, I did not catch this for a couple of days.

#sh int s0/0/0:23

Serial0/0/0:23 is up, line protocol is up (spoofing)

Per doc, the current valid MGCP PRI monitor is the D channel which is represented by the S0/0/0:23 that I posted and which corresponds with RTMT terminology of “DataLinkInService” below. Since the PRI was “spoofed” it showed up/up and RTMT could not alert us on it. I am currently revisiting the RTMT alert design to see if we can catch this in the future but given the current research, I am not sure if this is something RTMT can catch and be a limitation of the tool itself to this particular scenario.

DatalinkInService This counter represents the state of the Data Link (D-Channel) on the corresponding digital access gateway. This value will be set to 1 (one) if the Data Link is up (in service) or 0 (zero) if the Data Link is down (out of service).

Is there a way to catch this

I have this problem too.
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Jon Nelson Thu, 08/07/2008 - 06:13

This is by design. Your PRI's should be in spoofing mode.

When you do a show int s0/0/0:23 you should see this:

Serial0/0/0:23 is up, line protocol is up (spoofing)

Hardware is DSX1

MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation HDLC, loopback not set

Last input 00:00:27, output never, output hang never

Last clearing of "show interface" counters 00:00:02

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: weighted fair

Output queue: 0/1000/64/0 (size/max total/threshold/drops)

Conversations 0/1/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

Available Bandwidth 48 kilobits/sec

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

0 packets output, 0 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

Timeslot(s) Used:24, SCC: 0, Transmitter delay is 0 flags

If the D-channel goes down, RTMT will get an alert. Another way to check D-channel status is:

show isdn status

You should see MULTIFRAME-ESTABLISHED. If you see TEI-ASSIGNED, the D-channel more than likely isn't up and RTMT should generate alerts.

Thank you,



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