Frame relay quick notes
This page is quick notes for people wanting a run down on Frame Relay.
Frame Relay is a high performance Wan protocol that operates at the physical and data layers of the OSI model.
Devices attached to frame relay fall in to 2 categories
1, DTE, Data terminal equiptment, DTE equiptment are routers, bridges, PC'S,terminals
2, DCE, Data circuit terminating equiptment, The purpose of this is to provide clocking and switching.
When a router is connected to Frame Relay it sends an LMI inquiry to the network. The network then replies with an LMI status message containing details of every "VC" on the access list. VC is the connection of 2 DTE's
When Frame Relay receives a packet from ("IP" Internet protocol) it encapsulates it then passes it to the physical layer for delivery on the wire.
Cisco Frame Relay encapsulation uses a 4 byte headwith 2 bytes to identify the data link. It uses 2 bytes to identify the packet type. Frame Relay is used to connect Lans together.