[c-nsp] EtherSwitch HWIC Question

[Seth Mattinen]

Adrian Chadd wrote:
> On Mon, Jan 14, 2008, Seth Mattinen wrote:
>> I have a HWIC-4ESW module with POE. I'm pretty new to this module, so 
>> forgive my ignorance if I'm missing something totally obvious. =)
>>
>> Let's say I have ports Fa0/1/0, Fa0/1/1, and a subint on onboard Fa0/0.3 
>> that's a dot1q VLAN to an external switch. (Fa0/0 has two tagged 
>> subinterfaces.) Is it possible to join the etherswitch ports to the VLAN 
>> on Fa0/0.3? Fallback bridging complains because it's a subint on Fa0/0. 
>> My goal is to use the module to drive some wireless access points.
>>
>> I have been using an SVI for the etherswitch ports and routing all the 
>> wireless traffic in from their own network, but I was wondering if 
>> there's a way to keep it all layer 2 instead.
> 
> Nope. Well, short from connecting the onboard L3 port into a port on the
> HWIC; which is probably not what you desire.
> 
> I'd also benchmark the HWIC throughput and make sure you can drive the
> WAP's across the HWIC interconnect. I forget what the throughput is like
> for each integrated switch module, but you may find yourself thoroughly
> disappointed. Their L2 performance is fine, but when you start wanting
> to talk router -> hwic ports the interconnect becomes a problem.
> (This is why people loop an onboard l3 router port into a port on the
> HWIC in some circumstances.)
> 
> 

Ah, I figured as much. I *did* try connecting a port from the switch to 
a port on the HWIC, (Fa0/0 <-trunk-> switch <-untagged-> Fa0/1/0) but it 
  had problems; a wifi client could ping other devices on the switch, 
but not any IP on the router itself or anything that needed to be routed 
through the router (i.e. Fa0/1 to the world or a t1 to a branch office). 
I'm guessing it was an arp problem, but as I said, my experience with 
these things are quite limited.

SVI it is, then. Luckily I have the luxury of telling the wireless users 
in this case that if they want performance, they need to go find a wall 
jack and the wireless is for convenience only.

~Seth