1841 Routers & 2Mb Leased Line - Sessions dropping

[gordonmarkus]

Hi,

We have a customer with 2 sites, and a recently deployed 2Mb Leased line circuit between them. As the service provider does not provide routers, the customer has purchased an 1841 router for each site, along with a suitable serial interface to connect to the X21 interface on the provider eqpt.

With everything connected up, the serial interfaces come up ok (L1 and L2), and it's possible to ping/telnet to the remote router, and a server which sits on it's LAN interface. However, if we try to send a file to the remote server - the transfer starts to take place, and after about 10 seconds of transferring data the session times out, and we see CRC & input errors (equal in value) on the serial interface of the far end router.

I have cleared the counters to be sure, and can confirm that it's when the session dies, the counters increment.

I've tried a couple of things to try to get this working, one of which was to implement traffic shaping on the local router in the outbound direction to limit the rate at which the data was being sent. This made no difference, other than it took longer for the transfer to fail.

The Bandwidth on the serial interface at each end is configured ok. I've tried both HDLC and PPP encapsulation, and it makes no difference - the transfer still fails after a few seconds.

Both routers are running IOS 12.4-15.T7, and I've captured the config of the serial interface config for both routers, along with a 'show interface' on both routers

Any help or advice appreciated.

Regards,

-Gordon.

[gordonmarkus]

Hi,

The captures are here as they wouldn't fit in the original post:

interface Serial0/1/0

description Link to CC-FTM-02

bandwidth 2048

ip address 192.168.1.1 255.255.255.0

encapsulation ppp

fair-queue

Serial0/1/0 is up, line protocol is up

Hardware is GT96K Serial

Description: Link to CC-FTM-02

Internet address is 192.168.1.1/24

MTU 1500 bytes, BW 2048 Kbit/sec, DLY 20000 usec,

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

Encapsulation PPP, LCP Open

Open: IPCP, CDPCP, loopback not set

Keepalive set (10 sec)

CRC checking enabled

Last input 00:00:18, output 00:00:04, output hang never

Last clearing of "show interface" counters 00:02:29

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 0/2/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

Available Bandwidth 1536 kilobits/sec

5 minute input rate 0 bits/sec, 1 packets/sec

5 minute output rate 13000 bits/sec, 1 packets/sec

835 packets input, 57612 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

1225 packets output, 1181027 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

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

Hardware is GT96K Serial

Description: Link to CC-FTM-01

Internet address is 192.168.1.2/24

MTU 1500 bytes, BW 2048 Kbit/sec, DLY 20000 usec,

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

Encapsulation PPP, LCP Open

Open: IPCP, CDPCP, loopback not set

Keepalive set (10 sec)

CRC checking enabled

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

Last clearing of "show interface" counters 00:03:38

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 1536 kilobits/sec

5 minute input rate 3000 bits/sec, 2 packets/sec

5 minute output rate 1000 bits/sec, 2 packets/sec

1317 packets input, 1177403 bytes, 0 no buffer

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

7 input errors, 7 CRC, 7 frame, 0 overrun, 0 ignored, 7 abort

924 packets output, 62932 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

interface Serial0/0/0

description Link to CC-FTM-01

bandwidth 2048

ip address 192.168.1.2 255.255.255.0

encapsulation ppp

fair-queue

end

Thanks,

-Gordon.

[DialerString_2]

Gordon,

Those CRC errors could mean either the device sending the traffic is bad, patch cable is bad and/or duplex setting are off.

[gordonmarkus]

Cool - thanks for that. I'll get the hardware checked out.

Regards,

-Gordon.