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Interior Gateway Routing Protocol
IGRP Features and Operation
IGRP has several features included in the algorithm--these features and a
brief description can be found below in Table 6.1. Most of these features
were added to make IGRP more stable, and a few were created to deal with
routing updates and make network convergence happen faster.
IGRP is a classful protocol, which means it doesn't include any subnet
information about the network with route information.
Classful protocols are discussed in Chapter 2.
IGRP recognizes three types of routes:
Networks directly connected to a router interface.
T A B L E 6 . 1
IGRP Features
Configurable metrics
The user can configure metrics involved
in the algorithm responsible for
calculating route information.
Flash update
Updates are sent out prior to the default
time setting. This occurs when the
metrics for a route change.
Poison reverse updates
Implemented to prevent routing loops,
these updates place a route in
Hold-down means that the router
won't accept any new route information
on a given route for a certain period
of time.
Unequal-cost load balancing
Allows packets to be shared or
distributed across multiple paths.
Copyright ©2001 SYBEX , Inc., Alameda, CA