smds and loopback

[Guest_imported]

I had a problem today that bugs me.
We use smds at work, I am a ccna but have
never really had to mess with the circuit
before, basically the ASBR was someone elses
responsibility, and I took care of an internal
area.

We have been accumulating input errors, CRC, FRAME,
etc, on this interface. The service provider contacted
us with notice that he was getting alarms on the circuit
and wanted to check it.
My experience is basically with internal routing, layer 3
stuff, some vlan, etc.. dedicated ptp lines and smds
are new things. Is there some advice on what tshooting
to do on this from my end. Especially from the csu/dsu?

TIA
space

 

[jeter]

From the csu/dsu I would remove the interface and install a loop plug on the packet. The test center will have to put the circuit in a test mode. run this for about 3 minutes to determine if they are receiving a loop. If you do not have a loop plug you loop up the interface ( loopback line ).

What type of router are you using and what type of circuit.
I assume since you said csu/dsu it was a t1 connection. Jeter@LasVegas.com
J.Fisher CCNA

 

[benzito]

I'd let TelCo do their job and test the circuit for errors. There's a good chance that they'll find a problem on their end esp. since your receiving input errors. You can assist them in this by being at the site when they test the circuit. TelCo's responsible only to the point of demarcation <termination>. assuming you have a t1, then your circuit most likely terminates into a network interface card or &quot;smartjack&quot;. TelCo has the ability to &quot;loop&quot; the smartjack back so that they can test the integrity of the circuit. They will transmit certain bit patterns <BERT> to test the circuit and they will expect to get back on the recieve side exactly what was transmitted.

getting to the point...;-)

If they test the circuit and don't find any problems this is where you come in. If your router has an integrated csu / dsu on the WIC then you have the ability to put up your own loops so that you can test with your service provider. A &quot;line&quot; loop will loop ur csu back towards telco.Depending on your router model you can loop the csu or dsu back towards telco, you may also be able to issue a dte loop, payload loop, or others..just depends on your equip. If TelCo is able to test to the smartjack clean but your still seeing errors on your csu then start with the physical layer and work your way up. check the connection b/t the smartjack and your router, if there are any devices in the way such as patch panels or whatnot be sure to check them as well. <you could have a bad cable b/t you the smartjack and your csu, a flaky csu or the problem could be w/ the circuitry in the back card on the smartjack which is excluded by the test telco performs - these cards rarely go bad>

You really need to check out Cisco's web page on testing serial lines. There's A LOT of good info that will come in handy...

http://www.cisco.com/univercd/cc/td/doc/cisintwk/itg_v1/tr1915.htm

Benzito

 

[marsd]

Hey Guys, thanks for the url and advice.
Big help.

Here is some more info: opinions are welcome.

MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
SMDS hardware address is not set.
Encapsulation SMDS, loopback not set, keepalive set (10 sec)
Mode(s): D15 compatibility, DXI 3.2
DXI heartbeat sent 2252, DXI heartbeat received 2252
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of &quot;show interface&quot; counters 06:16:02
Queueing strategy: fifo
Output queue 0/1000, 0 drops; input queue 0/75, 0 drops
5 minute input rate 2000 bits/sec, 3 packets/sec
5 minute output rate 2000 bits/sec, 3 packets/sec
526861 packets input, 436316495 bytes, 4 no buffer
Received 0 broadcasts, 0 runts, 1 giants, 4 throttles
211 input errors, 115 CRC, 86 frame, 0 overrun, 0 ignored, 10 abort
455867 packets output, 94805008 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out 0 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up

After hours right now

 

[jeter]

Up 6 hours with a 116 CRC errors and 211 input errors. There still a problem here. I'm not 100% percent on this however try this ( sh service-module ) <-- interface for additional errors.
Jeter@LasVegas.com
J.Fisher CCNA