[ofa-general] Re: openSM: Different IB MTUs

[Hal Rosenstock]

Shirley,

On 7/25/07, Shirley Ma <xma at us.ibm.com> wrote:
>
>  Hal,
>
> Thanks for your prompt reply. I am asking for how openSM handle different
> link MTUs in SA MCMemberRecord MTU. For example, if we have some links MTU
> as 2K, some links MTU as 1K. Then when enabling IPoIB, how does SM decide
> IPoIB broadcast group MCMemberRecord MTU size? When creating an IB multicast
> group from a 2K MTU node first, which PMTU value is attaching to this IB
> multicast group MCMemberRecord MTU?
>

MCMemberRecord MTU gets the group MTU (when created). This is either this
first joiner with sufficient components or preconfigured (and MTU can be set
in the config). If a joiner has insufficient MTU for the group, it is
denied.

-- Hal


 Thanks
> Shirley Ma
>
> [image: Inactive hide details for "Hal Rosenstock"
> <hal.rosenstock at gmail.com>]"Hal Rosenstock" <hal.rosenstock at gmail.com>
>
>
>
>     *"Hal Rosenstock" <hal.rosenstock at gmail.com>*
>
>             07/25/07 10:57 AM
>
>
> To
>
> Shirley Ma/Beaverton/IBM at IBMUS
> cc
>
> general at lists.openfabrics.org
> Subject
>
> Re: openSM: Different IB MTUs
> Shirley,
>
> On 7/25/07, *Shirley Ma* <*xma at us.ibm.com* <xma at us.ibm.com>> wrote:
>
>    Hello Hal,
>
>    How does openSM handle CAs with different MTUs in the same subnet?
>    For example, IPoIB broadcast group MTU, IB multicast group PMTU? Does openSM
>    pick up the smallest MTU in the subnet?
>
>
>
> Are you asking about link MTU, SA PathRecord/MultiPathRecord MTU, SA
> MCMemberRecord MTU, or all of these ?
>
> -- Hal
>
>    Thanks
>    Shirley Ma
>
>
>
>
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