Description

Virtual circuits are established and cleared by sending messages on a separate control circuit. There is one control circuit for each network interface. Control circuits are permanently configured, rather than established using the circuit control protocol.

The control circuit operates in MSNL promiscuous mode: there can be multiple senders and multiple receivers. As cells from different senders may be interleaved on a promiscuous circuit, all messages sent must fit into a single cell.

Connections are requested or acknowledged based on the MSNL address and MSNL port.

Control messages typically contain or convey the following information not all of which is appropriate for each command.

• Command. Sometimes known as ``arptype''
• Originator's VCI
• Responder's VCI
• Originator's MSNL Address and Port
• Responder's MSNL Address and Port
• Argument

The following commands are defined.

0

Connection request

1

Connection reply

2

Connection close

3

Wait

4

Redirect

7

Rarp request based on 6 bit MDL value

8

Rarp reply for all request types

10

Rarp request based on 48 bit 802.2 Mac address value

11

Rarp request based on 16 bit Port Controller serial number

12

Topology beacon

13

Trivial topology response

14

Rarp request based on ORL allocated identifier

15

Allocated to ORL for experimentation.

16

Allocated to ORL for experimentation.

Commands 5, 6 and 9 are obsolete.