[ofa-general] Default multicast group rate

[Sasha Khapyorsky]

On 07:44 Fri 13 Apr     , Hal Rosenstock wrote:
> Hi,
> 
> There has been a lot of discussion over the last week on failed
> multicast joins.
> 
> The current default rate for multicast groups is 10 Gbps. This means
> that slower nodes (whether due to 1x SDR equipment or a degraded link)
> will fail the join.
> 
> The current default was chosen in the belief that most installations
> would be 4x SDR equipment or better (the most common use case) rather
> than the lowest common denominator use case. Also, choosing a lower
> default affects preformance of all multicast groups (which includes the
> IPv4 broadcast group as well as any other derived groups (not just IPoIB
> multicast groups)). So when certain performance tests are run, this will
> be a factor which needs to be investigated. The thinking was that those
> subtle things are harder (but perhaps less frequent) to find than the
> "harder" join error which forces the admin to decide one way or the
> other so there is no masking this.
> 
> So the question is whether the best default is 2.5 Gbps which would
> allow any nodes to join or whether the current default is appropriate ?
> I know certain people's opinions who have been vocal on this list up to
> now. I'm looking for other opinions. Thanks.

This value is configurable, and 10Gs/s as default looks reasonable
for me.

Sasha