Re: [lisp] #5: LISP protocol version is alive and kicking

[[e-mail] (Noel Chiappa)]

    > From: Sam Hartman <[e-mail]>

    > If no version information is included in the packet, then the site
    > may not know what version to use in its responses. ...
    > in the case where the site is going to use gleaned map cache
    > information, it may not have anything other than that first packet
    > to find out what version to use.

Light dawns over famous Massachussetts fishing harbour... :-) Sorry I was
a bit slow to catch on.

Yeah, that's a problem. (Puts on thinking cap, goes away to ponder for a
few days...)

    > You might argue that the map request could have carried your version
    > information. However, because of square routing and other concerns,
    > the map request and data packet may go to different places.

That's a general problem with square routing (i.e. packets from site A to
B flow from ITR a1 to ETR b1, packets back from B to A flow via ITR b2 and
ETR a2), and not just with the version information - the b2 ITR doesn't
have the mapping, either.

I've had it kicking around the back of my brain for a while now, but no
great hack has appeared. I suspect the only answers are painful (e.g.
better co-ordination between all the xTRs at a site - which we might need
anyway, for other reasons).

	Noel