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From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2006-12-06 07:55:59

On Dec 6, 2006, at 2:05 AM, Gleb Natapov wrote:

>> Actually I was wondering why there is a facility for having
>> multiple
>> LIDs for the same port. This led me to the entire series of
>> questions.
>> It is still not very clear to, as to what is the advantage of
>> assigning multiple LIDs to the same port. Does it give some
>> performance advantages?
> Each LID has its own path through the fabric (ideally), this is the
> way to
> lower a congestion.

More specifically, multi-LID support is best for networks where there
are multiple paths between the same pair of peers (e.g., a fat tree
network with multiple core switches). If you don't have a multi-
route topology on your IB network, multi-LID support from the same
port is not likely to be useful.

To answer your specific question: multi-LID support from a single
port is not a bandwidth multiplier because you're still sending and
receiving from a single port on the host (which has a fixed bandwidth

Jeff Squyres
Server Virtualization Business Unit
Cisco Systems