Lat Architecture; Virtual Circuit Layer; Slot Layer - Bay Networks 5390 Administering

LAT Architecture

LAT architecture consists of two layers: the virtual circuit layer and the slot layer.

Virtual Circuit Layer

The virtual circuit layer creates and maintains a virtual circuit between communicating LAT
machines. It also provides a data transport service for the slot layer. The virtual circuit translates
host names to Ethernet addresses. The first connection request to a unique host establishes a virtual
circuit.
The circuit_timer parameter determines the time interval between the transmission of LAT packets.
If there is no data to send, the virtual circuit goes into a "balanced" mode: either side can re-initiate
transmission if it has data to send. By default, a keepalive message is sent every 20 seconds.

Slot Layer

The slot layer is built on top of the virtual circuit layer, and has three functions:
• Establishing user sessions.
• Multiplexing sessions over a virtual circuit layer.
• Providing a transparent data transfer access service to LAT users.
The slot layer verifies and accepts a session in reverse LAT. Also, it sends and receives multicast
messages.
893-741-B
Network Protocols
C5-9