Re: [pilc] RE: AD request / L2 Triggers Chapter Statement

From: Lloyd Wood (l.wood@eim.surrey.ac.uk)
Date: Tue Jul 09 2002 - 18:07:01 EDT

  • Next message: Vernon Schryver: "Re: [pilc] RE: AD request / L2 Triggers Chapter Statement"

    On Tue, 9 Jul 2002, Joe Touch wrote:

    > >>>(Fortunately, routers that know about links and know about routing
    > >>>tables can use the information regardless if it's useful.)
    > >>
    > >>Routers know out-of-band info about links, communicated as data already.
    > >
    > >
    > > and not as a MIB. My question is: why are endhost implementations so
    > > STUPID compared to routers in this respect, in not even knowing what
    > > they're immediately connected to and whether it's there or not?
    >
    > Hosts that run routing software aren't.

    They are, because the routing software doesn't talk to the endhost
    applications. No real integration or communication between the two.

    > If you have a multihomed host,
    > run routing on that host. Embed the functionality of a router in the
    > endpoint, and call it a day - we did 5 years ago:
    >
    > "Dynamic Host Routing for Production Use of Developmental Networks"
    > J. Touch and T. Faber, Proc. ICNP '97, Atlanta, Oct. 1997, pp. 285-292.
    > (www.isi.edu/touch/pubs/)

    As for calling it a day - I see you couldn't maintain a TCP connection
    with it since you didn't have control of the source address the SunOS
    stack set - p5 - and you end with a plea for static loopback
    addresses, as found in all good router software for years, to fix
    this. No real integration.

    If you simply run routing software on the host the host's applications
    still can't know about local link connectivity, and they won't know
    about the routing software either.

    > > 1) MIBs aren't realtime. Not so sure they're desirable, either.
    >
    > IP isn't realtime either.

    Why not?

    > > 2) local implementations don't use MIBs to talk to themselves.
    > > An endhost using a MIB to tell itself about its own link
    > > interfaces? I don't think so.
    >
    > How do routers do it?

    A simple function call to find out would suffice. No MIB. Minimal
    running code. But routers are integrated beasts, while typical
    endhosts aren't.

    > Why is this new?

    That endhost stacks lack functionality is hardly a novel observation.

    L.

    <http://www.ee.surrey.ac.uk/Personal/L.Wood/><L.Wood@surrey.ac.uk>

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