Michael K. Smith - Adhost mksmith at adhost.com
Mon Apr 20 16:32:58 CDT 2009

Hello Deepak:

-----Original Message-----

So here is an idea that I hope someone shoots down.

We've been talking about pseudo-wires, and the high level of expertise a
shared-fabric IXP needs
to diagnose weird switch oddities, etc.

As far as I can tell, the principal reason to use a shared fabric is to
allow multiple connections to networks
that may not justify their own dedicated ($$$$) router port. Once they
do, they can move over to a PNI. However, an IXP is (at the hardware
level at least) trying to achieve any-to-any connectivity without
concern for capacity up to the port size of each port on every flow.
Scaling this to multiple pieces of hardware has posed interesting
challenges when the connection speed to participants is of the same
order as the interconnection between IXP switches.

So here is a hybrid idea, I'm not sure if It has been tried or seriously
considered before.

Since the primary justification for a shared fabric is cost savings....

What if everyone who participated at an IXP brought their own switch.
For argument's sake, a Nexus 5xxx. It has 20+ ports of L2, wire speed

[Michael K. Smith - Adhost] 

This sounds like fertile ground for unintended consequences.  Unmanaged
spanning tree topological changes as three people, previously connected
to their own switch and to others, now decide to connect to each other
as well, using those inexpensive L2 ports.



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