Motorola V3229 - 14.4 Kbps Modem Specifications download pdf (Page 87)

Configuring Asynchronous Lines and Interfaces

How to Configure Other Asynchronous Line and Interface Features

DC-33

Cisco IOS Dial Technologies Configuration Guide

Assigning asynchronous addresses dynamically is useful when you want to assign set addresses to users.

For example, an application on a personal computer that automatically dials in using Serial Line Internet

Protocol (SLIP) and polls for electronic mail messages can be set up to dial in periodically and enter the

required IP address and password.

To assign asynchronous addresses dynamically, use the following command in interface configuration

mode:

The dynamic addressing features of the internetwork allow packets to get to their destination and back

regardless of the access server, router, or network they are sent from. For example, if a host such as a

laptop computer moves from place to place, it can keep the same address no matter where it is dialing in

from.

Logical host names are first converted to uppercase and then sent to the TACACS server for

authentication.

See the following sections for examples of configurations that allow asynchronous addresses to be

assigned dynamically:

• Access Restriction on the Asynchronous Interface Example

• Asynchronous Routing and Dynamic Addressing Configuration Example

• Network Address Conservation Using the ip unnumbered Command Example

Optimizing Available Bandwidth

Asynchronous lines have relatively low bandwidth and can easily be overloaded, resulting in slow traffic

across these lines.

To optimize available bandwidth, perform either of the following optional tasks:

• Configuring Header Compression

• Forcing Header Compression at the EXEC Level

Configuring Header Compression

One way to optimize available bandwidth is by using TCP header compression. Van Jacobson TCP

header compression (defined by RFC 1144) can increase bandwidth availability two- to five-fold when

compared to lines not using header compression. Theoretically, it can improve bandwidth availability by

a ratio of seven to one.

To configure header compression, use the following command in interface configuration mode:

Command Purpose

Router(config-if)# async dynamic address

Allows the IP address to be assigned when the protocol is

initiated.

Command Purpose

Router(config-if)# ip tcp header-compression

[on | off | passive]

Configures Van Jacobson TCP header compression on the

asynchronous link.

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Motorola V3229 - 14.4 Kbps Modem Specifications Page 87