[Beowulf] Spanning Tree Protocol and latency: allowing loops in switching networks for minimizing switch hops
Eric W. Biederman
ebiederm at xmission.com
Tue Feb 23 21:03:33 PST 2010
Greg Lindahl <lindahl at pbm.com> writes:
> On Tue, Feb 23, 2010 at 03:15:28PM -0600, Rahul Nabar wrote:
>> On Tue, Feb 23, 2010 at 3:10 PM, Greg Lindahl <lindahl at pbm.com> wrote:
>> > On Tue, Feb 23, 2010 at 01:23:59PM -0600, Rahul Nabar wrote:
>> >> In the interest of latency minimum switch hops make sense and for that
>> >> loops might sometimes provide the best solution.
>> > STP disables all loops. All you gain is a bit of redundancy, but the
>> > price is high.
>> I see! That makes sense. Too bad. I wish there was some non-STP way
>> of dealing with loops then.
> Managed switches often include a non-STP way of finding and
> suppressing broadcast storms -- I know HP and Cisco have that.
> I don't know if it's any better than STP, though.
> In the InfiniBand world loops are encouraged & provide a nice
> performance benefit -- the routes are worked out globally by the
> Subnet Manager. Also, there is ethernet switch silicon that has an
> alternate routing mechanism that's as good as IB -- but I don't
> remember if it's standardized or compatible between different silicon
For the most trivial of loops there is link aggregation.
For more interesting loops you can run many ethernet switches
as wire speed ip routers talking a routing protocol like ospf.
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