[ofa-general] opensm: Routing on non-pure Fat-Tree

[Nicolas Morey Chaisemartin]

Yevgeny Kliteynik a écrit :
> Hi Nicolas,
>
> Nicolas Morey Chaisemartin wrote:
>> Hello,
>>
>> I am conducting some tests on routing non-pure fat-tree network using 
>> the fat tree algorithm of OpenSM.
>> The network I am experimenting on is a 3 level fat tree, with a 
>> pruned 3rd layer.
>> By providing the root_guid_file, the algorithm works great !
>>
>> The problem is, we would like to add some service nodes directly on 
>> the 3rd level switches.
>> I have added the cn_guid_file so the network is still recognize as a 
>> fat tree.
>> OpenSM once more manage to create the routing for the network. It 
>> provides full connectivity,
>> except there are no routes between non computes nodes.
>> I understand that the point of setting these node as not compute node 
>> should intend they won't talk to each other, but we still need a bit 
>> of connectivity between them to exchange few datas (pings and such).
>> A simple min-hop or such should be enough to generate those routes.
>> It will probably desequilibrate the number of routes going through 
>> the top links, but those additional link makes virtually no traffic 
>> at all, so in practical it shouldn't be a problem.
>
> Fat-tree should create full connectivity as long as there is an up/down
> route between ports. Do you get connectivity between these nodes with
> up/down routing algorithm?
> Try running it with the same root_guid_file.
>
> -- Yevgeny

Well the route would be more down/up compared to the rest of the transfer.
(Im not sure I was clear, but when i talk of 3rd level, I mean top 
level. 1st level begin the switches just above the compute nodes)
I'll try this tomorrow

Thanks

Nicolas
>
>> Is there any reasons such a behaviour wasn't implemented yet? Should 
>> there be one?
>>
>> Regards
>>
>> Nicolas Morey-Chaisemartin
>>
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