[c-nsp] OTT: layer-2 IX Q

[Niels Bakker]

* nick at arc.net.my (Nick Kraal) [Fri 27 Oct 2006, 12:39 CEST]:
>Just a quick OTT question.
>
>What are the caveats/booby-traps to look out for when implementing a 
>triangular WAN layer-2 IX network design? For one, one port (and thus 
>one link) will be blocked due to STP. Chatty design?
>
>        RouteServer
>            |
>         SwitchA
>          /   \
>         /     \
>   SwitchB ----SwitchC
>
>Links between the switches are WAN 1G/Ethernet links on single-mode dark 
>fiber.

You'll either be talking STP to devices connected to those switches, or 
you'll be vulnerable to possible loops behind each port on them.

Running normal STP you'll have pretty high convergence times with lots 
of unknown unicast flooding during link flaps, which will have an impact 
on the switches' CPUs.  Also, one link will remain completely unused 
during normal operations, which is a waste of fiber and interfaces.


	-- Niels.

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