[olug] Switch port errors...

[Phil Brutsche]

Replace your patch cables before you do anything else. Bad copper can
cause framing errors.

On 7/27/2010 1:23 PM, Dan Linder wrote:
> I'm still diagnosing my Cox Cablemodem port errors issue....  It's a case of
> "Windows is fine" but everyone else is complaining!
> 
> Here's my setup:
> 
> Cisco 2900XL port 23 ==> Cox Cable Modem (Motorola Surfboard SB5101U)
> (Crossover from modem to switch port)
> Cisco 2900XL port 22 ==> Linux firewall
> Cisco 2900XL port 21 ==> unused
> (All three ports are in the same VLAN)
> All speed tests were performed to www.speedtest.net using "Dallas".
> The Cisco and Linux interfaces are set to 100/Full -- didn't pursue that
> with the laptops yet.
> 
> We plugged a Windows system directly into my cablemodem ethernet port, then
> ran speed tests to the Omaha cox server and got 30Mbit/sec downloads and
> 6.5Mbit upload speeds (I have their new SOHO 25/5 package).  We swapped out
> cablemodems and used their tester modem and it too got 30/6Mbit.
> 
> When we put their laptop onto port 22, then power-cycled the cablemodem
> their speeds were ~1.8Mbit and 6Mbit down/up respectively (YES, less than 2
> Mbit DOWNLOAD speed just through the switch).
> 
> Before running the test through the switch I did a "clear counters" to reset
> the error counters.  After running the test (~15 seconds total), I see this:
> SW001#sh int fas 0/23
> ...
>   Output queue 0/40, 0 drops; input queue 0/75, 0 drops
>   5 minute input rate 153000 bits/sec, 43 packets/sec
>   5 minute output rate 97000 bits/sec, 27 packets/sec
>      4775 packets input, 4929578 bytes
>      Received 226 broadcasts, 0 runts, 0 giants, 0 throttles
> *     99 input errors, 41 CRC, 58 frame, 0 overrun, 0 ignored*
>      0 watchdog, 1 multicast
>      0 input packets with dribble condition detected
>      4661 packets output, 3039483 bytes, 0 underruns
> *     0 output errors, 0 collisions, 0 interface resets*
>      0 babbles, 0 late collision, 0 deferred
>      0 lost carrier, 0 no carrier
>      0 output buffer failures, 0 output buffers swapped out
> 
> If I plug the cablemodem straight into my Linux firwall, or into my laptop
> running Linux, both see the input errors (from the modem) on the ethernet
> port so I doubt it's a bad NIC or switch port.
> 
> My next steps:
>  * Replace the cables
>  * Move to new switch ports just in case.
>  * Replace the firewall NIC
>  * Test using my old cablemodem (Surfboard SB5101) on my @Home service.
>  ** Move my old cablemodem to the SOHO service and see if speed changes.
>  * Use a sniffer and setup port spanning on the cablemodem side.
>  * Research how to get better diagnostics out of the Surfboards.
> 
> Any other suggestions?
> I'm pulling my hair out on this one...and I don't have that much left!
> 
> Dan
> 

-- 

Phil Brutsche
phil at brutsche.us