MultiPort/LT User Reference
Page 23
Inside MultiPort/LT and Monitor Commands
2.1.6.2. Uses for IPTalk
There are two applications for IPTalk, both of which allow AppleTalk packets to
go where EtherTalk packets usually can't. Firstly, IPTalk allows delivery over
established IP networks that don't transport other AppleTalk protocols. For an
example of this see Figure 2-2 in the example presented later in this section.
Secondly, IPTalk allows communication between AppleTalk-based devices and
those that can only communicate using IP, such as most Unix-based computers.
IPTalk allows a pathway for delivery of AppleTalk packets to applications
running in these computers, notably the CAP-library-based applications aufs
and lwsrv.
As as example of IPTalk being used for AppleTalk packet delivery over
established IP networks, consider the Macintosh below printing a document on
the LaserWriter shown.
Normally one would not expect to print on such a remote LaserWriter - this is
just a simple example to show how the MultiPort/LT and IPTalk are involved.
IP Router
MultiPort/LT 1
MultiPort/LT 2
Figure 2-2.
IPTalk Operation
1. Macintosh sends AppleTalk packet to MultiPort/LT 1.
2. MultiPort/LT knows from atalkad that to reach destination it must
send packet to MultiPort/LT 2, and to get there it must go through the
IP router.
3. MultiPort/LT 1 encapsulates AppleTalk packet within an IP packet,
and sends it to IP Router.
4. IP Router forwards the IP packet to second MultiPort/LT.
5. MultiPort/LT 2 strips off IP packet to reveal AppleTalk packet.
6. MultiPort/LT 2 forwards AppleTalk packet to the LaserWriter.
