Packet structure

+---------------------------+
|             Flag          |
|          (1 Octet)        |
+---------------------------+
|             VPI           |
|          (1 Octet)        |
+---------------------------+
|             VCI           |
|         (2 Octets)        |
+---------------------------+
|           Payload         |
.                           .
.                           .
.                           .

Description

The flag field contains a value that is one of:

• 0, if the payload is raw traffic;
• 1, if the payload is a LANE frame, beginning with a LANE header;
• 2, if the payload is LLC-encapsulated traffic, beginning with an 802.2 LLC header;
• 3, if the payload is MARS traffic;
• 4, if the payload is IFMP traffic;
• 5, if the payload is ILMI traffic;
• 6, if the payload is Q.2931 traffic.

The VPI and VCI fields contain the VPI and VCI values for the payload; the VCI field is in network byte order.