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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 22 Configuring IP Unicast Routing
Configuring EIGRP
feasible successors, but there are neighbors advertising the destination, a recomputation must occur.
This is the process whereby a new successor is determined. The amount of time it takes to recompute
the route affects the convergence time. Recomputation is processor-intensive; it is advantageous to
avoid recomputation if it is not necessary. When a topology change occurs, DUAL tests for feasible
successors. If there are feasible successors, it uses any it finds to avoid unnecessary recomputation.
• The protocol-dependent modules are responsible for network layer protocol-specific tasks. An
example is the IP EIGRP module, which is responsible for sending and receiving EIGRP packets
that are encapsulated in IP. It is also responsible for parsing EIGRP packets and informing DUAL
of the new information received. EIGRP asks DUAL to make routing decisions, but the results are
stored in the IP routing table. EIGRP is also responsible for redistributing routes learned by other
IP routing protocols.
Table 22-9 shows the default EIGRP configuration.
Table 22-9 Default EIGRP Configuration
Feature Default Setting
Auto summary Enabled. Subprefixes are summarized to the classful network
boundary when crossing classful network boundaries.
Default-information Exterior routes are accepted and default information is passed
between IGRP or EIGRP processes when doing redistribution.
Default metric Only connected routes and interface static routes can be redistributed
without a default metric. The metric includes:
• Bandwidth: 0 or greater kbps.
• Delay (tens of microseconds): 0 or any positive number that is a
multiple of 39.1 nanoseconds.
• Reliability: any number between 0 and 255 (255 means
100 percent reliability).
• Loading: effective bandwidth as a number between 0 and 255
(255 is 100 percent loading).
• MTU: maximum transmission unit size of the route in bytes. 0 or
any positive integer.
Distance Internal distance: 90.
External distance: 170.
EIGRP log-neighbor changes Disabled. No adjacency changes logged.
IP authentication key-chain No authentication provided.
IP authentication mode No authentication provided.
IP bandwidth-percent 50 percent.
IP hello interval For low-speed nonbroadcast multiaccess (NBMA) networks:
60 seconds; all other networks: 5 seconds.
IP hold-time For low-speed NBMA networks: 180 seconds; all other networks:
15 seconds.
IP split-horizon Enabled.
IP summary address No summary aggregate addresses are predefined.
Metric weights tos: 0; k1 and k3: 1; k2, k4, and k5: 0
