>Hi All,
>
>LLC Type 1 = Unacknowledged Connectionless = TCP/IP, IPX, OSI, NetBIOS
>over IP/IPX etc....
>LLC Type 2 = Connection Oriented = SNA, NetBIOS over NetBEUI
>
>LLC Type 3 = Acknowledged Connectionless = ???
>
>I can't find a specific example of a service using the Type 3 LLC.......
>
>Anyone help with an example where Type 3's are used?
LLC Type 3 documentation is hard to find, because it was developed in
a standards-oriented context beyond the IEEE. In fact, I don't think
it ever actually became part of 802.2.
LLC 3 was developed by the Manufacturing Automation Protocol industry
group, of which the lead company was General Motors. It was designed
for real-time process control of factory robots, using the
Manufacturing Message Protocol at layer 7, null OSI layers 6 through
3, LLC3 at the upper part of layer 2, and IEEE 802.4 token bus at MAC
on down.
The typical configuration would be:
Cell controller ---|
loaded with MMS
command files via FTAM
file transfer
OSI FTAM -------->MMS-------->MMS-controlled robot
OSI ASN.1 BER -
OSI Session -
OSI TP4 -
OSI CLNP - -
LLC 1 LLC3 LLC3
Factory network----802.4 ----802.4---
(local to cell)
The stack with null layer 3-6 was called the MAP Enhanced Performance
Architecture stack, and had sufficiently tight timing requirements
that no form of relaying -- routing, bridging, etc., would be used
inside the manufacturing cell. The factory network that connected
the cell controllers, however, had full stacks (note that they ran
LLC1 and relied on TP4 for reliable transfer). The factory network
could contain routers and bridges.
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