[Beowulf] building Infiniband 4x cluster questions

Hearns, John john.hearns at mclaren.com
Mon Nov 7 07:45:39 PST 2011

> hi John,
> I had read already about subnet manager but i don't really understand
> this, except when it's only configuration tool.
> I assume it's not something that's critical in terms of bandwidth, it
> doesn't need nonstop bandwidth from the machine & switch is it?

It is critical.

I perhaps am not explaining this correctly.
In an Ethernet network you have a MAC address and the process of ARPing
ie if you want to open a connection to another host on the Ethernet,
you broadcast its IP address and you get returned a MAC address.
Hey, that's why its called an ETHERnet (geddit? Oh, the drollery of
those Xerox engineers)

Anyway, on an Infiniband network the Subnet Manager assigns new hosts a
LID (local identifier)
and keeps track of routing tables between them.
No SM, no new hosts join the network.

An Infiniband expert will be along in a minute and explain that you can
operate a fabric without an SM
and I shall stand corrected.

The contents of this email are confidential and for the exclusive use of the intended recipient.  If you receive this email in error you should not copy it, retransmit it, use it or disclose its contents but should return it to the sender immediately and delete your copy.

More information about the Beowulf mailing list