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sdlc interface down very often

mjwo
Level 1
Level 1

Hello,

In my customer site, SDLC device connect to 2600. IOS version is 12.0.7T. Then access AS400 through DLSW function. We showed log and found the connected interface down very often. show log as below.

We checked AS400 log and didn't find the SDLC device inactive ever. And we check SDLC device, the device work well, user didn't find any problem??

We don't know why always log of message showed the interface down.

Anyone can help me??

.Jun 23 08:29:56 Taiwan: %LINK-3-UPDOWN: Interface Serial1/0, changed state to down

.Jun 23 08:29:57 Taiwan: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to down

.Jun 23 08:30:01 Taiwan: %LINK-3-UPDOWN: Interface Serial1/0, changed state to up

.Jun 23 08:30:02 Taiwan: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to up

.Jun 23 08:33:06 Taiwan: %LINK-3-UPDOWN: Interface Serial1/0, changed state to down

.Jun 23 08:33:07 Taiwan: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to down

.Jun 23 08:33:11 Taiwan: %LINK-3-UPDOWN: Interface Serial1/0, changed state to up

.Jun 23 08:33:12 Taiwan: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to up

.Jun 23 08:36:16 Taiwan: %LINK-3-UPDOWN: Interface Serial1/0, changed state to down

.Jun 23 08:36:17 Taiwan: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to down

.Jun 23 08:36:21 Taiwan: %LINK-3-UPDOWN: Interface Serial1/0, changed state to up

.Jun 23 08:36:22 Taiwan: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to up

.Jun 23 08:39:25 Taiwan: %LINK-3-UPDOWN: Interface Serial1/0, changed state to down

.Jun 23 08:39:26 Taiwan: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to down

.Jun 23 08:39:30 Taiwan: %LINK-3-UPDOWN: Interface Serial1/0, changed state to up

.Jun 23 08:39:31 Taiwan: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/0, changed state to up

JSB025a#sh inter se 1/0

Serial1/0 is up, line protocol is up

Hardware is CD2430 in sync mode

Description: connect to SNA pu2.1

MTU 1500 bytes, BW 128 Kbit, DLY 20000 usec,

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

Encapsulation SDLC, loopback not set

Half-duplex enabled.

cts-delay 0 milliseconds

dcd-txstart-delay 100 milliseconds

dcd-drop-delay 100 milliseconds

transmit-delay 0 milliseconds

Errors - 0 half duplex violation

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: 4000.2625.01--

sdlc addr 01 state is CONNECT (xid-poll)

cls_state is CLS_IN_SESSION

VS 5, VR 0, Remote VR 5, Current retransmit count 0

Hold queue: 0/200 IFRAMEs 116636/58170

TESTs 0/0 XIDs 40235/14460, DMs 6784/6736 FRMRs 0/0

RNRs 7/0 SNRMs 9757/0 DISC/RDs 9733/0 REJs 0/0

Poll: clear, Poll count: 0, ready for poll, chain: 01/01

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

Last clearing of "show interface" counters 9w3d

Queueing strategy: fifo

Output queue 0/40, 0 drops; input queue 0/75, 0 drops

5 minute input rate 0 bits/sec, 50 packets/sec

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

156063821 packets input, 318338246 bytes, 0 no buffer

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

11 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 11 abort

155708948 packets output, 337016303 bytes, 0 underruns

0 output errors, 0 collisions, 43092 interface resets

0 output buffer failures, 0 output buffers swapped out

106807 carrier transitions

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

9 Replies 9

emazurek
Cisco Employee
Cisco Employee

Hi,

I believe that your line keeps bouncing due to Data

Carrier Detect(DCD) going down. I didn't see a copy

of the interface config but do you have the following

command under your interface?

half-duplex controlled-carrier

This in conjunction with the dcd-txstart-delay and

dcd-drop-delay settings will cause the DCE to drop

DCD frequently.

These are for very specialized environments which

probably are not what you have.

What is your environment, with respect to the

connection to the AS/400? Is it just a Cisco DCE

cable connected to an AS/400 cable? Or are there

other cables/switches/modems involved?

If you just have the Cisco DCE cable connected to

the AS/400's cable then you do not need that command.

Otherwise, it is possible you have a cable or

physical interface problem.

Please include your interface's config if this

information wasn't enough to resolve the problem.

Thanks and regards,

Ed Mazurek

jishi
Level 1
Level 1

Hello,

I would first think some problems on the router or something wrong on the AS400, since it "misses" the DCD at so accurate intervel. Did you try to replace the port or the card? Can you do a debug serial interface? and can you provide an output of sh control?

When router desert the DCD, it should not bring down the interface.

Thanks

Jing

steve.rivkind
Level 1
Level 1

All the responses you have gotten are right. You can have the user check the Network card on the AS400 it could be faulty. If this has been done or the card has been replaced try reseating the cable or moving the device to another serial interface and see if that works to resolve the issue

Hello,

Thank you for your reply!!

In this customer's site, totally there are 40 branch office, and there are 40 SNA gateway in every branch office. SNA gateway connect to router interface by sdlc card directly. And every branch office got the same problem.

Interface configuration as below:

interface Serial1/0

description connect to SNA pu2.1

no ip address

no ip directed-broadcast

encapsulation sdlc

no keepalive

half-duplex

nrzi-encoding

clockrate 19200

sdlc role primary

sdlc vmac 4000.2625.0100

sdlc address 01 xid-poll

sdlc partner 4000.0400.0001 01

sdlc dlsw 1

I make sure there is not physical problem, just don't know why!!

Regards,

May

emazurek
Cisco Employee
Cisco Employee

Hi May,

Thanks for the information.

Are you saying that there are a total of 1600 of

these SNA gateway PUs(40*40) and that they are all

doing this?

I think the next thing to do is to run a "debug

serial interface" command on one of the routers.

Run this for a short time until you see the interface

reset counter increment. Try and capture the entire

telnet log and send it to me. I'll be glad to take

a look. This debug shouldn't put out that much

information so it should be relatively safe. It will

capture information pertaining to the state of the

interface and will not capture any actual data

packets. You can either run the debug to the log or

to the console via the "logging console" config

command and/or the "terminal monitor" command.

You turn off the debug with the "undebug all"

command.

Thanks,

Ed Mazurek

emazurek@cisco.com

Hi Ed,

There are totally 40 SNA gateway PUs.

I would debug serial interface later,

Thank you for your help!!

Regards,

May

jihicks
Cisco Employee
Cisco Employee

Hi May,

Something else you might try changing at one of the branches. The default for poll-pause timer is 10ms. This means that the router and controller might exchange receiver ready ( RR ) as often as 100 times a second. This may be too often for the attached controller. Try changing one of these to 200 ms with the interface command:

sdlc poll-pause-timer 200

Best regards,

Jim

Is there some kind of "keepalive" timer set to be 60 seconds on the device? When it misses 3 consecutive "keepalives" it drops the DTR? It must be a configuration/setup problem.

Thanks

Jing

I would get together with who ever configures the SNA gateway and make sure that the settings on the gateway match those on the interface. If the gateway settings are good maybe check with the VTAM folks to make sure it matches. Noticed the clockrate is set for 19200. Maybe set if it should be 56000 and put in a line speed statement of 19200. Example:

clockrate 56000

sdlc line-speed 19200

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