RESOLVED: Connection timed out

Matthew Pope mpope at teksavvy.com
Wed Feb 14 21:18:44 UTC 2007


Greg,
Your email was very helpful. I isolated the freebsd box, and the win2K 
box on a LAN without connection to the upstream Cisco device, and all 
the connectivity problems went away. I'll be implementing the 'turn off 
STP' on those Cisco ports shortly.
Many thanks,
Matthew
Greg Barniskis wrote:

> Matthew Pope wrote:
>
>> I find that during the blocking behaviour, when I try and ping the 
>> windows box, a tcpdump shows that each second ping attempt is 
>> followed by a response (it appears) from an IPv6 address...
>
>
>> 13:30:51.066625 802.1d config 8000.00:30:19:53:05:00.8011 root 
>> 8000.00:30:19:53:05:00 pathcost 0 age 0 max 20 hello 2 fdelay 15
>> 13:30:53.069431 802.1d config 8000.00:30:19:53:05:00.8011 root 
>> 8000.00:30:19:53:05:00 pathcost 0 age 0 max 20 hello 2 fdelay 15
>
>
> If you're referring to the above samples as "appears from IPV6", those 
> are Spanning Tree Protocol packets originating from the Cisco switch, 
> and are unrelated to your ping test. You will see them on the wire 
> frequently even in the absence of any normal IP traffic.
>
> You probably want the following Cisco configuration directive added to 
> those switch ports that do not connect the 2900 to other switches:
>
> spanning-tree portfast
>
> The presence of the STP packets may or may not be related to your 
> performance issues. They shouldn't be, but some buggy NICs/drivers do 
> seem to get freaked out by STP.
>
> When STP is enabled on a switch port, it definitely will delay your 
> initial link establishment by 30 seconds or so, when the attached 
> computer is first powered up. That alone can confuse things when the 
> NIC is trying to negotiate a link speed and the switch is still 
> thinking about STP. It's even possible that you're getting a link 
> speed/duplex mismatch out of it, and of course that will play holy 
> hell with your response time.
>
>


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