Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
New Member

Line Problem

I have a 14.4 leased line which I use to connect the central office with my remote site. I have used Codex Modems on both sides and Cisco 2611 and 1601 routers on the central and remote sites respectively. The line has been losing a lot of packets hence inefficient for my purpose. The Telcom company says its my fault but i don't believe them because the configuration on the routers and modems are similar to the rest of my routes and modems and the R232(60,15) cables have been properly tasted. Below are the interface statistics of the serial line of the central site router:

Serial1/3 is up, line protocol is up

Hardware is CD2430 in sync mode


Internet address is

MTU 1500 bytes, BW 128 Kbit, DLY 20000 usec, rely 130/255, load 1/255

Encapsulation HDLC, loopback not set, keepalive set (10 sec)

Last input 00:00:03, output 00:00:00, output hang 2d06h

Last clearing of "show interface" counters never

Input queue: 0/75/0 (size/max/drops); Total output drops: 656

Queueing strategy: weighted fair

Output queue: 0/1000/64/649 (size/max total/threshold/drops)

Conversations 0/41/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

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

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

158266 packets input, 8775562 bytes, 0 no buffer

Received 107449 broadcasts, 0 runts, 3 giants, 0 throttles

5683310 input errors, 3263774 CRC, 0 frame, 0 overrun, 0 ignored, 2419503 abort

248544 packets output, 45704953 bytes, 0 underruns

0 output errors, 0 collisions, 56701 interface resets

0 output buffer failures, 0 output buffers swapped out

89 carrier transitions

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

What could be causing such a problem?


Re: Line Problem

That's a lot of input errors, but from this one output it is impossible to tell if the line is bad. Clear the counters on the interface and run the show interface command again, and see if there are more input errors. Also look at the carrier transitions field.

If you are still receiving errors, run whatever diagnostics you can do between the modem and the router. For instance, can you loop the modem back to the router? If so, see if you get errors. If you do, you have a local problem in either the modem, the router or the cable. If you are not getting errors with that loopback, loop the distant modem back to the line and see if there are errors, if possible. Errors with this test will point to a line problem.

Good luck.


Re: Line Problem


Adding to Marks remarks,i need to tell u if u hve a Bert Meter u can check at u r end by looping the remote end modem.if u get errors on the test then obviosuly the problem of line.the reliability is also too low it shuld be 255/255 for a error free link.



New Member

Re: Line Problem


I just want the signification of the reliability.



Re: Line Problem

Reliability is calculated using the following formula:

reliability = number of errors / number of total frames

On your interface you have a lot of aborts , this usually indicates a clocking problem , whos is providing clock ? check the CSU's or have the provider check the csu's make sure both sides are not providing clock or are providing clock , only one side or the line should provide clock. , check with the carrier for slips ,

CreatePlease to create content