Cisco IOS Wide-Area Networking Configuration Guide - Free Books

Configuring Frame RelayCustomizing Frame Relay for Your NetworkSee the following sections for information about configuring or disabling TCP/IP header compression:• Configuring an Individual IP Map for TCP/IP Header Compression• Configuring an Interface for TCP/IP Header Compression• Disabling TCP/IP Header CompressionNoteIf you configure an interface with Cisco-proprietary encapsulation and TCP/IP header compression,Frame Relay IP maps inherit the compression characteristics of the interface. However, if you configurethe interface with IETF encapsulation, the interface cannot be configured for compression. Frame Relaymaps will have to be configured individually to support TCP/IP header compression.Configuring an Individual IP Map for TCP/IP Header CompressionNoteAn interface configured to support TCP/IP header compression cannot also support priority queueing orcustom queueing.TCP/IP header compression requires Cisco-proprietary encapsulation. If you need to have IETFencapsulation on an interface as a whole, you can still configure a specific IP map to useCisco-proprietary encapsulation and TCP header compression. In addition, even if you configure theinterface to perform TCP/IP header compression, you can still configure a specific IP map not tocompress TCP/IP headers.You can specify whether TCP/IP header compression is active or passive. Active compression subjectsevery outgoing packet to TCP/IP header compression. Passive compression subjects an outgoing TCP/IPpacket to header compression only if a packet had a compressed TCP/IP header when it was received.To configure an IP map to use Cisco-proprietary encapsulation and TCP/IP header compression, use thefollowing command in interface configuration mode:CommandRouter(config-if)# frame-relay map ip ip-address dlci [broadcast]tcp header-compression [active | passive] [connections number]PurposeConfigures an IP map to use TCP/IP headercompression. Cisco-proprietary encapsulationis enabled by default.For an example of how to configure TCP header compression on an IP map, see the section “Using anIP Map to Override TCP/IP Header Compression Example” later in this chapter.Configuring an Interface for TCP/IP Header CompressionYou can configure the interface with active or passive TCP/IP header compression. Active compression,the default, subjects all outgoing TCP/IP packets to header compression. Passive compression subjectsan outgoing packet to header compression only if the packet had a compressed TCP/IP header when itwas received on that interface.To apply TCP/IP header compression to an interface, you must use the following commands in interfaceconfiguration mode:47