Subject: [karp] BFD Authentication costs

From: "Joel M. Halpern" <[email-masked]>
Date: Wed, 31 Jul 2013 07:31:02 -0400

The presentation on the cost of BFD authentication was interesting.  And 
the suggestion from the crypto folks that there are far more efficient 
mechanisms is clearly worth looking at.

But a related question occurred to me.

In practice, on most devices, when BFD is run at low intervals it is 
done directly on the line card.  Doesn't this mean that in most 
topologies the number of sessions is roughly the same as the number of 
physical ports on the device?

Yours,
Joel

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From: "Bhatia, Manav (Manav)" <[email-masked]>
Date: Wed, 31 Jul 2013 11:36:38 +0000

Hi Joel,
 
> In practice, on most devices, when BFD is run at low 
> intervals it is done directly on the line card.  Doesn't this 
> mean that in most topologies the number of sessions is 
> roughly the same as the number of physical ports on the device?

Not necessarily. Our customers use vlan tagged IP Interfaces where the # of sessions on a physical port can be greater than 1 (and it usually is).

Cheers, Manav

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From: "Russ White" <[email-masked]>
Date: Wed, 31 Jul 2013 08:38:23 -0400

> Not necessarily. Our customers use vlan tagged IP Interfaces where the #
of
> sessions on a physical port can be greater than 1 (and it usually is).

I would say this is pretty normal --ie, customers running multiple logical
interfaces is more common than the one-to-one situation, in my experience.

Russ

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From: Joel Halpern Direct <[email-masked]>
Date: Wed, 31 Jul 2013 08:39:38 -0400

After I sent my note, I thought of some cases on my own.  But I do think 
it is important that we think about the scale at which we want to make 
this work.

Yours,
Joel

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From: "Joel M. Halpern" <[email-masked]>
Date: Wed, 31 Jul 2013 08:40:22 -0400

Yours,
Joel