Re: Multiple TCP/IP servers on one host


kwe@bu-it.bu.edu (kwe@bu-cs.bu.edu)
8 Sep 88 18:17:51 GMT


In article <957@helios.ee.lbl.gov> dagg@lbl.gov (Darren Griffiths) writes:
>
>I have missed some of the recent discussions on this list, so I haven't seen
>any of the previous messages you are referring to, but it sounds like you are
>talking about something similar to one of my pet nags about routing (I know
>there are a lot of different nags about routing, but this is my favorite). In
>many cases there are different paths to the same host, either via backup
>redundant links or because of longer hops through the network. Usually the
>gateways know about these different paths and take the fastest (determined by
>the metric) and leave the other path untouched. This other path may be idle
>and quite useful, there are two ways of making use of this path.
>
        When you say "different paths" do you mean alternate routes to
the same address or alternate addresses to the same host (which is the
subject of the thread)? In the first case, you as a user don't care
what paths your datagrams take so long as they get there quickly.
However, load sharing is done by ciscoIGRP and is proposed in Moy's
Open SPF IGP protocol draft for equal-cost routes.

        Presumably, the untouched routes are being used by other
datagram streams.

        If you mean alternate addresses to the same host, that won't
work for a telnet stream, will it? How would a router know anything
about relationships between IP addresses?

> 2) The second thing that can be done is a little nicer. The gateways could
> look in to the tcp packets and send some of the stuff through one route
> and some through another. For example, SMTP connections do not always
> need to be taking up bandwidth on a high speed link when they could be
> using a slower backup link leaving the high speed connections for
> interactive users. Real people tend to be a lot more impatient than
> computers (although real people are also a lot slower at many things.)
>

        One set of warnings: "stateful routers" and "router crash".
But what you are suggesting could be a Type of Service kind of thing.
Better than having the router decide, the application can tell the
router about what it wants in the way of security, delay, bandwidth,
etc.

        Kent England, BU



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