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From: Tappan@G.BBN.COM (Dan Tappan)
Newsgroups: mod.protocols.appletalk
Subject: Re: InterBridge + FastPath = ?
Message-ID: <8609221909.AA07088@ucbvax.Berkeley.EDU>
Date: Mon, 22-Sep-86 13:25:30 EDT
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Posted: Mon Sep 22 13:25:30 1986
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    Date: Sun, 21 Sep 86 20:25:13 edt
    From: brad%gcc-milo.UUCP@harvard.HARVARD.EDU (Brad Parker)
    Newsgroups: mod.protocols.appletalk
    Subject: InterBridge + FastPath = ?

    Has anyone used the CAP 2.01 gateway code with a Hayes interbridge?
    Everything works fine until I turn on the interbridge:

    .....

I don't have an interbridge to play with, but I can make some guesses:

1) The RTMP doc. in inside mac "suggests" sending RTMP updates every
5 seconds (with a "gateway down" timeout of 10 seconds). The Seagate/Kinetics
UDP gateway code sends an RTMP packet every 30 seconds. 30 seconds seems
like a much better number as far as not wasting appletalk bandwidth, but
likely the Interbridge close 5 seconds. This means two things
  i) It probably is declaring the Kinetics down.
  ii) Since it sends so many more packets than the Kinetics the Mac always
     choses it as "a_bridge".

2) Even assuming the RTMP stuff was in sync, the UDP gateway code does
not do a full RTMP. It wouldn't be hard to make it forward to the Interbridge
properly, but there are a few things that might be alittle painful:
  o  The spec says gateways "cooperate in forwarding BrRq nbp packets to
     all nets" It doesn't say how. Specificly it's not clear whether
     the InterBridge will forward the BrRq packet to the Kinetics box, and
     in what form.
  o  The appletalk routing protocol is fairly simplistic, more or less like
     the old Arpanet GGP which broke down under alot of networks. The CAP
     code uses a routing server. The interface to the routing server needs
     to be extended alittle so the Kinetics box can generate a RTMP packet
     that will tell the InterBridge all the nets that it (the Kinetics box)
     can reach.

I suppose someone needs to sit down with an Interbridge and resolve 
these issues. Probably the biggest one is the "send-RTNP" interval,
I don't think I would want several bridges broadcasting every 5 seconds
on my appletalk net.

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