Re: Ethernet card?

[derek@slab.cisco.com (Derek Taubert)]

In <madsci-0810961235550001@ppp-71.ts-5.nyc.idt.net> Erick Dietrich wrote:
> In article <mvgfrDyyH9J.CF3@netcom.com>, mvgfr@netcom.com (Marc Farnum
> Rendino) wrote:
> 
> 
> > Has anyone used any of those LocalTalk-to-Ethernet bridges?  (Commonly
> > used for LocalTalk-only printers.) I think I'll do a little
> > 'spearmint...
> 
> 
> I've got my IIgs onto several Ethernets with the help of Farallon's
> LocalPath.  Its a software router that runs on the macintosh.  Install the
> software on an ethernetted mac, plug in a localtalk box on the printer
> port,  and connect up to 8 nodes to your segment.  Performance was very
> good, even on a Mac II.  File transfers seem faster from ethernet - to -
> the IIgs than they are from other Localtalk nodes to the IIgs.
> 
> One thing I'm not sure of is wether LocalPath routes anything other than
> AppleTalk.  It prolly won't do TCP/IP.

TCP/IP over Localtalk uses a special kind of encapsulation called MacIP.  The 
IP packets are buried inside of Appletalk DDP packets.  Since LocalPath 
routes Appletalk packets, the data will make it from the Localtalk media to 
the Ethernet media as Appletalk packets without any problem.  The question to 
ask is this: does LocalPath supports MacIP de-encapsulation to convert MacIP 
packets into Ethernet IP packets and vice-versa.

Once the packet ends up on the Ethernet side, it will have the following 
encapsulations:

	1) Ethernet
	2) Appletalk (1 and 2 together make EtherTalk)
	3) DDP
	4) IP

You basically have to strip off #1-#3 and then create a new #1 to shove the 
remaining #4 into.

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