Subject: Re: [rrg] [lisp] [Int-area] Please respond: Questions from the IESG as towhether a WG forming BOF is necessary for LISP

From: [email-masked] (Noel Chiappa)
Date: Mon, 26 Jan 2009 17:50:34 -0500 (EST)

> From: Dino Farinacci <[email-masked]>

    > if you are going to claim liveness through a protocol, you have to send
    > control packets all the time from M ITRs to N ETRs.

I find this terminology somewhat non-intuitive, and wonder if it's too late
to change it. To me, "liveness" would imply as to whether something is live
or dead, i.e. up or down. (Such state detection can obviously be performed on
ITR I1's behalf by I2, and the result communicated locally from I2 to I1.)

The issue of whether packets from ITR Im can reach ETR En (which is where you
run into the need for M*N) I would describe as "reachability". (So if there's
a routing problem, or an access control setting, that prevents I1 from
getting to E7 even through I1 can get to E8 and I2 can get to E7, that would
be a reachability problem on the {I1, E7} pairing.) I seem to recall this
term being used in at least one routing protocol, although I can't now recall
which one.

        Noel
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From: Dino Farinacci <[email-masked]>
Date: Mon, 26 Jan 2009 18:05:01 -0800

> ITR I1's behalf by I2, and the result communicated locally from I2  

I think its only documented in the Dave/Darrel draft. But they use the  
term "path liveness" so I think that is a more appropriate term.

> term being used in at least one routing protocol, although I can't  

Right, Dave/Darrel referred to it as "reachable paths", "testing  
reachability", "is there path liveness". Those sorts of terms.

Dino