[Cerowrt-devel] Recording RF management info _and_ associated traffic?

David Lang david at lang.hm
Sun Jan 25 21:43:03 EST 2015

On Sun, 25 Jan 2015, Dave Taht wrote:

> To your roaming point, yes this is certainly one place where migrating
> bridged vms across machines breaks down, and yet more and more vm
> layers are doing it. I would certainly prefer routing in this case.

What's the difference between "roaming" and moving a VM from one place in the 
network to another?

As far as layer 2 vs layer 3 goes. If you try to operate at layer 3, you are 
going to have quite a bit of smarts in the endpoint. Even if it's only connected 
vi a single link. If you think about it, even if your network routing tables 
list every machine in our environment individually, you still have a problem of 
what gateway the endpoint uses. It would have to change every time it moved. 
Since DHCP doesn't update frequently enough to be transparent, you would need to 
have each endpoint running a routing protocol.

This can work for individual hobbiests, but not when you need to support random 
devices (how would you configure an iPhone to support this?)

Letting the layer 2 equipment deal with the traffic within the building and 
invoking layer 3 to go outside the building (or to a different security domain) 
makes a lot of sense. Even if that means that layer 2 within a building looks 
very similar to what layer 3 used to look like around a city.

back to the topic of wifi, I'm not aware of any APs that participate in the 
switch protocols at this level. I also don't know of any reasonably priced 
switches that can do anything smarter than plain spanning tree when connected 
through multiple paths (I'd love to learn otherwise)

David Lang

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