[c-nsp] intra-chassis stacking

[Joe Abley]

Hi all,

I am puzzling over a cisco 2851 which has both a HWIC-D-9ESW 9-port  
switch module and a NM-16ESW-1GIG 16+1 port switch module.

The switch modules do not seem to be behaving as I would expect. ARPs  
are succeeding and failing apparently at random, OSPF adjacencies are  
not forming, and general layer-2 badness abounds.

The small amounts of cisco docs available about this configuration  
suggest that "intra-chassis stacking" must be configured, but details  
on exactly what that means are a little light. The best indication I  
have seen suggests that I need to insert a crossover cable between  
the optional gigabit modules on each of the cards; however, it  
doesn't seem like gigabit ports are an option on the 9-port HWIC, and  
the gig port on the 16+1-port NM is already in use.

I have no requirement for VLANs to span the two modules -- I can  
easily keep all the ports on the 9-port HWIC in a single VLAN, and  
not expect any ports in the 16+1-port NM to join those VLANs.

Any suggestions as to whether this configuration can be made to work  
in a sane way?


Joe