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Pitto
Asked: 2011-01-20 04:58:41 +0800 CST

Find out why internet connection is slow (Cisco 2600)

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I have a cisco 2600 connecting us to the internet.

a ping to www.google.com is 1500 ms: very high.

If I do a tracert I get very fast on the "outside" and then every hop takes 1000 ms or more. I've phoned the adsl company but they say that their tests were perfect and the problems are on my cisco 2600. I have no experience of cisco... Any hints about commands I could try to understand if the hardware's ko or I have to keep on calling my provider?

I update the question with the latest data I get:

#sh int s0/0

Serial0/0 is up, line protocol is up

Hardware is PowerQUICC Serial

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

reliability 255/255, txload 27/255, rxload 9/255

Encapsulation FRAME-RELAY IETF, loopback not set

Keepalive set (10 sec)

LMI enq sent 1183342, LMI stat recvd 1183344, LMI upd recvd 0, DTE LMI up

LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0

LMI DLCI 1023 LMI type is CISCO frame relay DTE

Broadcast queue 0/64, broadcasts sent/dropped 0/0, interface broadcasts 0

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

Last clearing of "show interface" counters 19w3d

Input queue: 0/75/11309/0 (size/max/drops/flushes); Total output drops: 1587

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 57000 bits/sec, 54 packets/sec

5 minute output rate 167000 bits/sec, 59 packets/sec

461062254 packets input, 2656249300 bytes, 44 no buffer

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

106 input errors, 32 CRC, 44 frame, 0 overrun, 0 ignored, 30 abort

475466652 packets output, 2402577905 bytes, 0 underruns

0 output errors, 0 collisions, 7 interface resets

0 output buffer failures, 0 output buffers swapped out

24 carrier transitions

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

The MTU suggestion in actual answers was not resolving my issues

cisco internet

4 Answers

  1. I would use the show interface command (at least I hope IIRC on that command) and for any transmit or receive errors from the interface connected to the ASDL modem. For example:

    Test# show int F0/0
FastEthernet0/0 is up, line protocol is up 
  Hardware is DEC21140, address is ca00.4da5.0000 (bia ca00.4da5.0000)
  Internet address is 192.168.45.1/24
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec, 
     reliability 255/255, txload 1/255, rxload 1/255
  ...
  5 minute output rate 0 bits/sec, 0 packets/sec
     0 packets input, 0 bytes
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     ...
     0 output errors, 0 collisions, 1 interface resets

    Also try extensive pings form the cisco router to the next hop from the router. The ping command will allow you to send larger payloads at a faster rate by using various options. See if larger total number of pings and a larger payload causes any packet loss. For example:

    Test# ping 192.168.24.1 size 1000 repeat 300

    (Using the size argument is also useful for testing for MTU issues that gravyface mentioned)

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  2. What's the MTU set to on your Cisco? I had the same issue with an 1841 that I had swapped in place of an existing SonicWall that immediately degraded the Internet connection. I was able to resolve it by changing the MTU size on I believe the inside interface as described here.

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  3. Do you have an ADSL WIC in the Cisco 2600 or is an external modem? If it's external, try connecting it directly to a computer to see if the issue is with the router or ADSL line.

    Also, perhaps posting a show running-config might help see if there's anything glaringly wrong on the router.

    Depending on how your logging is configured, you might find something in show log if you're lucky.

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  4. Best Answer

    Could you please show us a traceroute to, for example, www.google.com ? If you get +1000ms just after your Cisco 2600, it probably means that someone on your LAN is consuming all the ADSL bandwidth.

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