Equipment Support > Hardware By Brand > Cisco > E1\T1 circuit - serial interface errors

E1\T1 circuit - serial interface errors

If you believe that the work performed by BT has caused the issue, log a fault with your provider and get the service checked out.

If you can post a "show interface" we can see how many errors you are talking about. At the moment we have nothing to go by.

Naturally a high number of errors will lead to packet loss which will result in degraded performance. And if this is the case, see my first paragraph.

Hi Tom,

Thank you for taking the time and trouble to respond.

If only it was as easy as logging a fault with the provider! As I said in my OP BT and Globix are blaming each other and that's not getting it fixed.

The E1 circuit has been active and in use for > 3 years with only very occasional problems. Last month we took over some more office space in our building and decided to move a lot of equipment to the new space on the ground floor. This meant having the copper for the E1 circuit rerouted from the comms room in the basement to the ground floor, an internal shift only no cease and reprovision. At their insistence BT rebuilt the circuit completely and this has lead to all of the problems. When BT do their testing, either at their exchange (the CO) or at our sire they report that no fault was found or errors seen on the line. But when the circuit is in use i.e. under load we do see errors, here's a sample output from a sh int s0/0 command.

Serial0/0 is up, line protocol is up

Hardware is PowerQUICC Serial

Internet address is ***.***.***.***/30

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

reliability 252/255, txload 31/255, rxload 37/255

Encapsulation HDLC, loopback not set

Keepalive set (10 sec)

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

Last clearing of "show interface" counters 04:25:05

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 2052

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 230000 bits/sec, 61 packets/sec

5 minute output rate 188000 bits/sec, 59 packets/sec

1825861 packets input, 1091411760 bytes, 0 no buffer

Received 1579 broadcasts, 0 runts, 0 giants, 0 throttles

27666 input errors, 26793 CRC, 461 frame, 0 overrun, 0 ignored, 412 abort

1692465 packets output, 644949078 bytes, 0 underruns

0 output errors, 0 collisions, 3 interface resets

0 output buffer failures, 0 output buffers swapped out

2 carrier transitions

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

There have been other periods of up to 36 hours between resetting the counters on the interface when there are no errors at all.

Here's the capture from another period.

Serial0/0 is up, line protocol is up
Hardware is PowerQUICC Serial
Internet address is ***.***.***.***/30
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 243/255, txload 9/255, rxload 11/255
Encapsulation HDLC, loopback not set
Keepalive set (10 sec)
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters 03:05:59
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 1226
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 71000 bits/sec, 29 packets/sec
5 minute output rate 57000 bits/sec, 31 packets/sec
477063 packets input, 227131029 bytes, 0 no buffer
Received 759 broadcasts, 0 runts, 46 giants, 0 throttles
1488927 input errors, 123240 CRC, 639750 frame, 0 overrun, 0 ignored, 725934 abort
472889 packets output, 203873735 bytes, 0 underruns
0 output errors, 0 collisions, 120 interface resets
0 output buffer failures, 0 output buffers swapped out
14 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up

So the only part of this whole E1 circuit that has changed is that which is provided, controlled and managed by BT.

I've tried using a different router, WIC-1T and serial cable and all of the possible permutations of items without any improvement.

Globix assure me that they have not made any changes at their end.