SDLC Problem

Answered Question
Aug 26th, 2008

As a financial institution we use SDLC to connect to our vendor managed ATM's. At one site we are unable to connect and I'm having trouble determining whether it's a DCE(Router) or DTE (ATM).


Here is what is being displayed on the serial interface.


Serial0/3/0 is up, line protocol is up

Hardware is GT96K Serial

MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,

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

Encapsulation SDLC, loopback not set

Router link station role: PRIMARY (DCE)

Router link station metrics:

slow-poll 10 seconds

T1 (reply time out) 3000 milliseconds

N1 (max frame size) 12016 bits

N2 (retry count) 20

poll-pause-timer 10 milliseconds

poll-limit-value 1

k (windowsize) 7

modulo 8

sdlc vmac: 4000.0106.20--

sdlc addr 4E state is SNRMSENT

cls_state is CLS_STN_CLOSED

VS 0, VR 0, Remote VR 0, Current retransmit count 126

Hold queue: 0/200 IFRAMEs 0/0

TESTs 0/0 XIDs 0/0, DMs 0/0 FRMRs 0/0

RNRs 0/0 SNRMs 1150/87 DISC/RDs 0/0 REJs 0/0

Poll: set, Poll count: 0, chain: 4E/4E

Last input never, output 00:00:01, output hang never

Last clearing of "show interface" counters 00:21:03

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

Queueing strategy: fifo

Output queue: 0/40 (size/max)

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

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

87 packets input, 174 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

421 packets output, 842 bytes, 0 underruns

0 output errors, 0 collisions, 5 interface resets

0 output buffer failures, 0 output buffers swapped out

3 carrier transitions

DCD=up DSR=up DTR=up RTS=down CTS=up


It seems to me we are sending packets but not receiving data back (SNRMSENT)


The vendor insists he is not receiving any packets at all. Cable has been tested and 3 WIC cards have been replaced. Anybody have any ideas on how to further troubleshoot?


Also here is debug for SDLC packets/Events


Aug 26 11:26:22: Serial0/3/0 SDLC output 4E93

Aug 26 11:26:25: Serial0/3/0: SDLC T 4E SNRMSENT 0xE8886C T 88

Aug 26 11:26:25: Serial0/3/0: SDLC O 4E SNRMSENT (2) SNRM P s: 0 r: 0 rr: 0

Aug 26 11:26:25: Serial0/3/0 SDLC output 4E93

Aug 26 11:26:28: Serial0/3/0: SDLC T 4E SNRMSENT 0xE89424 T 89

Aug 26 11:26:28: Serial0/3/0: SDLC O 4E SNRMSENT (2) SNRM P s: 0 r: 0 rr: 0

Aug 26 11:26:28: Serial0/3/0 SDLC output 4E93

Aug 26 11:26:31: Serial0/3/0: SDLC T 4E SNRMSENT 0xE89FDC T 90

Aug 26 11:26:31: Serial0/3/0: SDLC O 4E SNRMSENT (2) SNRM P s: 0 r: 0 rr: 0

Aug 26 11:26:31: Serial0/3/0 SDLC output 4E93

Aug 26 11:26:34: Serial0/3/0: SDLC T 4E SNRMSENT 0xE8AB94 T 91

Aug 26 11:26:34: Serial0/3/0: SDLC O 4E SNRMSENT (2) SNRM P s: 0 r: 0 rr: 0

Aug 26 11:26:34: Serial0/3/0 SDLC output 4E93

Aug 26 11:26:37: Serial0/3/0: SDLC T 4E SNRMSENT 0xE8B74C T 92

Aug 26 11:26:37: Serial0/3/0: SDLC O 4E SNRMSENT (2) SNRM P s: 0 r: 0 rr: 0




Correct Answer by Richard Burts about 8 years 6 months ago

James


It is difficult to tell from what is posted just what the problem is. I am not seeing things that point the problem at the router. I do note a couple of things:

- the counters were reset recently and since they were reset you have sent 421 frames and received 87.

- the 87 received may match to this line of output:

RNRs 0/0 SNRMs 1150/87 DISC/RDs 0/0 REJs 0/0

- the debug output is showing your router attempting to send and at least in the short duration of the debug is not showing any response received.


I wonder if the ATM were reset, if the symptoms would change.


And I wonder if the head end would vary off and vary on the SDLC device if the symptoms would change.


HTH


Rick

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Correct Answer
Richard Burts Tue, 08/26/2008 - 07:56

James


It is difficult to tell from what is posted just what the problem is. I am not seeing things that point the problem at the router. I do note a couple of things:

- the counters were reset recently and since they were reset you have sent 421 frames and received 87.

- the 87 received may match to this line of output:

RNRs 0/0 SNRMs 1150/87 DISC/RDs 0/0 REJs 0/0

- the debug output is showing your router attempting to send and at least in the short duration of the debug is not showing any response received.


I wonder if the ATM were reset, if the symptoms would change.


And I wonder if the head end would vary off and vary on the SDLC device if the symptoms would change.


HTH


Rick

jtalbaugh Tue, 08/26/2008 - 09:19

Thanks for the help Rick. I cut off the log because it was just incrementing with the same log entries. Everything to me showed the router attempting to communicate but not getting a response but I was running out of ideas on how to prove it wasn't the router.


Needless to say the vendor found the problem on the ATM (After 5 days)


Thanks for you input.

Richard Burts Tue, 08/26/2008 - 09:26

James


Thank you for posting back to the thread and indicating that the problem was resolved and what the resolution was. Thank you for using the rating system to indicate that your problem was resolved (and thanks for the rating). It makes the forum more useful when people can read about a problem and can know that the problem was successfully resolved.


HTH


Rick

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