Cisco IOS Wide-Area Networking Configuration Guide - Free Books

Configuring Frame RelayCustomizing Frame Relay for Your Network• Verifying Payload CompressionConfiguring Packet-by-Packet Payload CompressionYou can configure payload compression on point-to-point or multipoint interfaces or subinterfaces.Payload compression uses the Stacker method to predict what the next character in the frame will be.Because the prediction is done packet by packet, the dictionary is not conserved across packetboundaries.Payload compression on each VC consumes approximately 40 kilobytes for dictionary memory.To configure payload compression on a specified multipoint interface or subinterface, use the followingcommand in interface configuration mode:CommandRouter(config-if)# frame-relay map protocol protocol-address dlcipayload-compression packet-by-packetPurposeEnables payload compression on amultipoint interface.To configure payload compression on a specified point-to-point interface or subinterface, use thefollowing command in interface configuration mode:CommandRouter(config-if)# frame-relay payload-compression packet-by-packetPurposeEnables payload compression on apoint-to-point interface.Configuring Standard-Based FRF.9 CompressionSelecting FRF.9 Compression MethodFrame Relay compression can now occur on the VIP board, on the Compression Service Adapter (CSA),or on the main CPU of the router. FRF.9 is standard-based and therefore provides multivendorcompatibility. FRF.9 compression uses relatively higher compression ratios, allowing more data to becompressed for faster transmission. FRF.9 compression provides the ability to maintain multipledecompression/compression histories on a per-DLCI basis.The CSA hardware has been in use on the Cisco 7200 series and Cisco 7500 series platforms, but it hashad no support for Frame Relay compression. The CSA can be used in the Cisco 7200 series or in thesecond-generation Versatile Interface Processor (VIP2) in all Cisco 7500 series routers. The specificVIP2 model required for the CSA is VIP2-40, which has 2 MB of SRAM and 32 MB of DRAM.See the following sections for further information on FRF.9 compression:• Selecting FRF.9 Compression Method• Configuring FRF.9 Compression Using Map Statements• Configuring FRF.9 Compression on the SubinterfaceThe router enables compression in the following order:1. If the router contains a compression service adapter, compression is performed in the CSA hardware(hardware compression).43