[crossbow-discuss] Re: [clearview-discuss] IPMP and Crossbow

[James Carlson]

Peter Memishian writes:
> 
>  > > That's why IPMP uses ICMP probes -- to discern path failures.
>  > 
>  > That's always an option as well, and the way it works today in the code. 
>  > I.e. probe-based detection failure would be required when using IPMP on 
>  > top of VNICs. If that's an acceptable requirement I'm fine leaving the 
>  > code as-is :-)
> 
> I think it would only be OK if in.mpathd can figure out whether a given IP
> interface supports link-based falure detection, and require the customer
> to configure test addresses if it does not.

Yes.  The point is that VNICs that allow "local" communication while
the remote link is down can't claim to have link-based failure
detection.

>  (This is a problem today as
> well, but since most links currently support link-based failure detection,
> it's not as pressing a problem.  If there isn't one already, I'll log a
> bug on this.)

It sounds like the sort of thing that's somewhat in the NWAM court.

> I suspect there will also be a fair number of customers who will be
> disappointed in not having link-based failure detection over VNICs, since
> it's become a very popular configuration choice.

Yes.  But as long as the VNIC is emulating an internal connection to a
bridge or repeater of some sort, I think the answer makes a fair bit
of sense.

Now, if someone were to update the 802 protocols to allow a switch to
notify other ports when one port fails ...

-- 
James Carlson, Solaris Networking              <james.d.carlson at sun.com>
Sun Microsystems / 1 Network Drive         71.232W   Vox +1 781 442 2084
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