[openib-general] [PATCH 2/3] SA: add call to initializeib_ah_attr from a path record

[Suresh Shelvapille]

Jason:

This might work in this case. 
But, if you look at RFC4391(section 4.1 Broadcast GID params, item 4. other
parameters) :
    "The broadcast-GID's scope bits need to be set based on whether
    the IPoIB link is confined within an IB subnet or the IPoIB
    link spans multiple IB subnets.  A default of local-subnet
    scope (i.e., 0x2) is RECOMMENDED.  A node might determine the
    scope bits to use by interactively searching for a broadcast-
    GID of ever greater scope by first starting with the local-
    scope.  Or, an implementation might include the scope bits as
    a configuration parameter"


How can a node determine the scope param in Roland's crazy setup(when the
scope bits are not a config param)?

Thanks,
Suri

> -----Original Message-----
> From: openib-general-bounces at openib.org [mailto:openib-general-
> bounces at openib.org] On Behalf Of Jason Gunthorpe
> Sent: Thursday, May 18, 2006 11:10 PM
> To: Sean Hefty
> Cc: 'Roland Dreier'; openib-general at openib.org
> Subject: Re: [openib-general] [PATCH 2/3] SA: add call to
> initializeib_ah_attr from a path record
> 
> On Thu, May 18, 2006 at 04:24:16PM -0700, Sean Hefty wrote:
> 
> > I should note that I compared the subnet prefixes to determine if the
> GRH
> > should be used.  Reading back over the 'GRH flag in ib_ah_attr' thread,
> it
> > looks like there's consensus that hop_limit > 1 is the check that we
> want.
> > I will update the code accordingly.
> 
> I think it is also prudent to not use a GRH if the DGID's prefix is
> fe80::/64 (link local scope).
> 
> Jason
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