Internet Dropouts.. Collision Count High?? on this Cisco 828 router??

Posted on 2007-03-21
Last Modified: 2012-06-22
Hi I am troubleshooting internet dropouts on our network. Bloomberg clients keep disconnecting and Im getting phones thrown at me each time it happens (well slight exageration)

I have the folllowing:

ISP - - -  Cisco 828 HSDL  - - -  Straight cable  - - - Cyberguard Snapgear SG560 Firewall

The Cisco is set to 10/half duplex.. The Cyberguard Firewall also 10/half duplex.

The ISP who manages this switch told me there is a problem with my firewall causing too many collissions...  

Any advice much appreciated. Cheers Wilson

The router has been on 20minutes.

See "show int eth0"  below:

User Access Verification

>show int eth0
Ethernet0 is up, line protocol is up
  Hardware is PQUICC Ethernet, address is 0011.5cf2.5a37 (bia 0011.5cf2.5a37)
  Description:  LAN
  Internet address is
  MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
     reliability 255/255, txload 1/255, rxload 9/255
  Encapsulation ARPA, loopback not set
  Keepalive not set
  Half-duplex, 10Mb/s
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:00, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/100 (size/max)
  5 minute input rate 385000 bits/sec, 41 packets/sec
  5 minute output rate 19000 bits/sec, 25 packets/sec
     256221 packets input, 204552633 bytes, 0 no buffer
     Received 408 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 input packets with dribble condition detected
     201972 packets output, 101437225 bytes, 0 underruns
     0 output errors, 3736 collisions, 1 interface resets
     0 babbles, 0 late collision, 1358 deferred
     0 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out
Question by:wilsonkjit
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Author Comment

ID: 18762451
pinging isp's dns server I loose approx 10%. d'oh

LVL 10

Expert Comment

ID: 18762784
replace cable between firewall and router.
LVL 20

Accepted Solution

RPPreacher earned 500 total points
ID: 18763001
90% of the time this is a speed/duplex issue.  Your e0/0 is 10Mbs half duplex.  Your firewall is probably auto or 100 full.
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Author Comment

ID: 18763004
Thanks for that.. I do try that though. New straight thru.

Would it usually be a straight thru between a router and a firewall??,, Maybe a crossover will be better?


Author Comment

ID: 18763013
The Cisco is set to 10/half duplex.. The Cyberguard Firewall was Auto but I set that to 10/half duplex, with no improvement.


Author Comment

ID: 18763020
I am right in saying the Collsion count is infact HIGH..3736? for a router powered up for only 20mins.  Does this look like my problem, or could this just be a red herring and the cause of my dropouts is somewhere else.

LVL 20

Expert Comment

ID: 18763053
Your collision count is high.  Did you clear the counts after changing your firewall from auto to 10/half?

Author Comment

ID: 18766543
Thanks for the reply..
Not manually, I power cycled the router to clear the counter. You can see the collisions growing when I do a download or upload. 100 per minute rate.
LVL 10

Expert Comment

ID: 18769561
Disconnect your LAN and then only connect one pc and start downloading. If CRC still increase you have to check the hardware interface on both devices.

Author Comment

ID: 18791145
Yes it ended up being a mismatched speed duplex setting, it took me a while to double check the advice given.

the Cisco 828 only supports 10mbps half duplex and the firewall was failing to auto negotiate.

Cheers for your help

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