[geeks] Switch incompatibilities

[David Passmore]

On Thu, Nov 29, 2001 at 10:34:06AM -0800, Fogg, James wrote:
> 
> My Christhall Bhall shows me you have macintosh's or dhcp'ing older
> windblows machines. One fluke of the Cisco switch is that spanning-tree
> portfast is disabled by default. This means that the port, though up/up, is
> NOT forwarding for up to 45 seconds when the attached host brings the link
> up. Also, you can do sh int f0/x and check that your link stats are what you
> think they are, then do sh span int f0/x and make sure its forwarding.

No Macs, no Windows, no DHCP. I had already turned portfast on; whether or
not it was turned on, the port would eventually show as FORWARDING in a show
spanning-tree, which is correct. 

> Another possiblity is that you HAVE loops, in which case you will surely
> have a broadcast storm going on and you won't pass traffic.

It's not possible to have loops on this network; the switches are connected
in series.

Either the Cisco or SMC switch is simply not passing IP packets (they are
passing broadcast ethernet packets, as evidenced by the fact that I can see
ARP requests). I can see MAC addresses of machines on the other side of the
link. It is a protocol level thing, not a physical thing, which is what
really has me stumped.

The SMC configuration is unmanaged. It's a cheap switch, but it talks to
other switches (Netgear) okay. The Cisco conf is vanilla (I reset it to
factory defaults).

David