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New Member

ATM circuit

I have a 10MB ATM circuit between 2 operations centers. This circuit is going down, but I am only seeing carrier transitions on one end of the link when this happens. Why am I only seeing this on one end? What does the carrier transition tell me about what is happening? Any hightly detailed and informative docs are appreciated. See the "show int" below:

ATM4/1/0 is up, line protocol is up

Hardware is cyBus ENHANCED ATM PA

Description: POC T3 Fiber (Ckt=DNEC.935038 AT&T=8002866621)

MTU 4470 bytes, sub MTU 4470, BW 44209 Kbit, DLY 190 usec,

reliability 255/255, txload 42/255, rxload 24/255

Encapsulation ATM, loopback not set

Keepalive not supported

Encapsulation(s): AAL5

4096 maximum active VCs, 1 current VCCs

VC idle disconnect time: 300 seconds

20 carrier transitions

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

Last clearing of "show interface" counters 04:05:27

Input queue: 0/100/0/2 (size/max/drops/flushes); Total output drops: 71

Queueing strategy: fifo

Output queue :0/100 (size/max)

30 second input rate 4289000 bits/sec, 1475 packets/sec

30 second output rate 7290000 bits/sec, 1638 packets/sec

19137594 packets input, 1633863208 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

21502671 packets output, 582729637 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

New Member

Re: ATM circuit

Hi John,

Carrier transition incrementing at one end show you more likely that the problem is nearest th isend.

how often this carrier transition increment ?

did you report this problem to the ATM circuit provider ?

From my point of view, it's more likely a circuit problem. If you have more details, please let us know.


Cisco Employee

Re: ATM circuit

Carrier transitions:

Number of times the carrier detect signal of a serial interface has changed state. For example, if data carrier detect (DCD) goes down and comes up, the carrier transition counter will increment two times. Indicates modem or line problems if the carrier detect line is changing state often.

you may want to try using an DS3 attenuator to make sure the signal comming

into the rx side of the interface is not too hot.

ATTEN-KIT-PA= is the cisco part number for the attenuator kit .



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