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New Member

High error rate on Cisco 805 serial


I have 2 Cisco 805 handling a 2 Mbits/s WAN link. Both are configured as DTE (receiving the clock). On the serial interface of the 805's, I have very high rate of input errors : most are 'frame' errors, some are 'abort' errors.

The Serial interface is up and the line protocol is up also, but, when issuing ping commands, about 5% are loss.

As the 2 Cisco are reporting the same errors on both side of the WAN link, I don't think the issue is coming from a hardware issue.

Please help. Thanks

Bellow the 'sh inter serial0' output :

Serial0 is up, line protocol is up

Hardware is PowerQUICC Serial

Description: connected to Morillon

Interface is unnumbered. Using address of Ethernet0 (

MTU 1500 bytes, BW 512 Kbit, DLY 20000 usec,

reliability 144/255, txload 1/255, rxload 1/255

Encapsulation PPP, LCP Open

Open: CDPCP, IPCP, loopback not set

Keepalive set (10 sec)

Last input 00:00:02, output 00:00:02, output hang never

Last clearing of "show interface" counters 00:14:35

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 0/1/128 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

Available Bandwidth 384 kilobits/sec

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

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

495 packets input, 72138 bytes, 0 no buffer

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

5375 input errors, 0 CRC, 5154 frame, 0 overrun, 0 ignored, 221 abort

471 packets output, 62636 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


Re: High error rate on Cisco 805 serial

Hi Phillipe

Cisco 805 routers support 512Kbps only if you are trying to pump up over the capacity you will of course tends to see these kinda drops.

So do limit the speed on your modem to 512Kbps and check for the drops.

If you still insist on working with 2 Mbps capacity its better watch out for a new router in Cisco 1800 Series.


New Member

Re: High error rate on Cisco 805 serial


Thank's a lot for your answer. I will try to make some tests at 512 KbIts/s and if not possible upgrade to a Cisco 1800.

Is a Cisco 1841 with a WIC-1T card will be able to handle a 2 Mbits/s X21 link ?

What is the maximum speed possible for this hardware ?


Re: High error rate on Cisco 805 serial

Hi Phillipe

Cisco 1841 accommodates WIC-1T card & have seen these routers even handling WIC-2T cards installed in it. So i dont see any problem in handling your 2Mbps bandwidth capacity..