Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!uwm.edu!spool.mu.edu!munnari.oz.au!mundamutti.cs.mu.OZ.AU!kre From: kre@cs.mu.OZ.AU (Robert Elz) Newsgroups: comp.protocols.appletalk Subject: Re: Picking node ID for CAP server Message-ID: Date: 17 Apr 91 10:01:26 GMT References: <1991Apr15.183923.27012@phri.nyu.edu> Sender: news@cs.mu.oz.au Lines: 26 roy@alanine.phri.nyu.edu (Roy Smith) writes: >Why can't >CAP engage in the dynamic node ID assignment (LLAP Enquiry/Acknowledge) >like every other AppleTalk object? The IPtalk protocol (that CAP uses in the way you're using it) requires a 1:1 mapping between IP address and appletalk address, so it knows to which IP address to send packets addressed to any particular appletalk address (things could have been done other ways, but they weren't). The IPtalk node number is the low 8 bits of your IP address (subnet masks are irrelevant here). No choice, no options, that's just how it is. What's not quite so clear is just why CAP requires you to configure it, instead of just configuring it ... I think that derives from very ancient history before the 1:1 mapping was created, and instead gateways had tables of addresses compiled in - and the direct relationship wasn't required. Needless to say this couldn't survive beyond the times when everyone built their own gateways with their own soldering iron... kre