Frame Relay to ATM Service Interworking (FRF.8) on the 7200 Series Router Using Inverse Multiplexing Over ATM (IMA)

Introduction

The Broadband Forum (formerly the Frame Relay Forum) defines the Frame Relay-to-ATM service interworking function in its FRF.8 implementation agreement. A typical configuration of FRF.8 consists of a Frame Relay endpoint, an ATM endpoint, and an interworking (IWF) device. A Cisco 7200 series router with a PA-A3 port adapter can provide the interworking functions as of Cisco IOS^® Software Release 12.1(5)T. Cisco 2600 and 3600 series routers and the MC3810 also can provide the interworking functions as well. The Frame Relay-to-ATM Service Interworking (FRF.8) feature benefits internet service providers that need to link Frame Relay and ATM networks, especially those networks with ATM backbones and Frame Relay end users.

Inverse Multiplexing over ATM (IMA) is a Broadband Forum specification (af-phy-0086.000). It involves inverse multiplexing and de-multiplexing of ATM cells in a cyclical fashion among physical links grouped to form a higher-bandwidth and logical link. The rate of the logical link is approximately the sum of the rate of the physical links in the IMA group. Streams of cells are distributed in a round-robin manner across the multiple T1/E1 links and reassembled at the destination to form the original cell stream. Sequencing is provided using IMA Control Protocol (ICP) cells.

This document presents a sample configuration for FRF.8 on a 7200 series router with a PA-8T1-IMA.

Prerequisites

Requirements

Before attempting this configuration, ensure that you meet these requirements:

• Understand router configurations for both Frame-Relay and ATM / IMA.

• Familiar with encapsulation types, frame, cell formats and layer 1 troubleshooting.

• Understand cabling.

Related topics not covered in this document can be found in the Related Information