🚀 go-pugleaf

In article <1e605dINN44o@roche.csl.sri.com> David Stine, dstine@cisco.com
writes:
>It is also possible that collisions can take out RTMP update packets
after
>they have been sent by the router. This is somewhat less likely.

AppleTalk was designed to run on LocalTalk, which has no collision
detection. Losing RTMP packets on LocalTalk is not a terribly rare
occurance. So any good implementation should have no problems with
lost RTMP packets.

>
>>My question comes up because if I sit at the console of the Novell print
>>server and watch the RTMP table, the next hop route to any given IP
site is
>>doing a 'musical chair routine' among the 30 some FastPaths.  Every 10
>>seconds or some the next hop changes nodes on the ethertalk segment!

You probably don't mean IP here. Or maybe you don't mean RTMP. What do you
mean?

>Well, this is something of an open area in the AppleTalk end-node design.
>Implementors who follow "Inside AppleTalk" to the letter will have their
>designated router possibly switch with every incoming RTMP packet. Please
>refer to pp. 5-18 and 5-19 in "Inside AppleTalk", 2nd. Ed.
>
>Some would say that this is a nuisance in AppleTalk, that it confuses the
>issue of trying to figure out where your traffic is going and why. These
folks
>tend to come from the IP world, where you either tell a Unix host to
>(statically) designate a default route to a router for all traffic or
you are
>running a routing protocol which tends to "lock on" to a path.
>
>So there are some AppleTalk end-node implementations which tend to stick
with
>the first router they hear as the value for A-ROUTER until they quit
hearing
>said router, at which time they pick another router on the cable.
>
>Then there is the flip side of the coin: by switching the value for
A-ROUTER
>with every update, you effect a sort of "load sharing" between the
routers
>present on a cable.
>
>Which is better? I'm sure we can find arguments in favor of both.

Actually, it doesn't really matter much which you do, as long as you
implement
the "Optional best-router cache" described on Inside AppleTalk (V2) p
4-20.
All but the most rudimentary of network devices should be able to
implement
this cache. If you do this, then the only thing A-Router does for you is
tell you where to send your NBP requests.

-Steve