Frame Relay
Networking - Wide Area Network

Frame Relay works with several protocols:

IP DECnet AppleTalk XBS Novell IPX CLNS ISO Banyan Vines Transparent Bridging

Most WAN services provide communications interface between DCE and DTE devices, Frame Relay is no exception. Just like X.25 Frame Relay is a connection-oriented program that communicates across packet switched networks. The difference is that Frame Relay is must faster and more efficient that X.25.

Network congestion is big problem with Frame Relay. When the data that creates the congestion becomes too much the data must be either delayed or discarded. There are two types of mechanisms that are used to reduce network congestion, DE (Discard Eligibility) and ECN (Explicit Congestion Notification). There are two different types of ECN, FECN (Forward) and BECN (Backward). DE is the mechanism that decides which frames to throw out, it is better that the sending device decides which packets to through out instead of the router which will just throw out packets at random.

Frame Relay

Operates at the Physical and Data Link layers using speeds from 64Kbps to 1.544Mbps. It allows voice, video, and data over a WAN connection.

Terms and Definitions:

VC (virtual circuit) –path used between terminals

PVC (permanent virtual circuit)- permanent VC connection

SVC (switched virtual circuit)- dynamically enabled

DTE (data terminal equipment)

DCE (data communications equipment) frame relay switches

DLCI (Data-Link Connection Identifier) Frame relay device that identifies the routers or destination device that is to receive the frame.

LMI (Local Management Interface)- enhancements to the frame relay protocol, and a signaling standard between a frame switch and a router. Three types of LMI, Cisco, ANSI, q933a.

CIR (Committed Information Rate) The dedicated bandwidth on frame relay for you.

When configuring a router for Frame Relay you must specify an encapsulation type. Either CISCO or IETF. Config Router for Frame Relay- Enabling

RouterHome(config)#int s0 RouterHome(config)#encapsulation frame-relay ietf (or Cisco)