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<strong>the</strong> different IP address spaces in<strong>to</strong> a working policy is also an<br />

alternative.<br />

Route Redistribution<br />

It is not uncommon <strong>to</strong> have more than one routing pro<strong>to</strong>col operating<br />

in a large inter<strong>network</strong>/intra<strong>network</strong>. Not all IP routing pro<strong>to</strong>cols are<br />

supported by <strong>network</strong> hardware vendors. Some vendors even have<br />

<strong>the</strong>ir own proprietary pro<strong>to</strong>cols (for example, Cisco's IGRP and EIGRP).<br />

Having multiple routing domains enables you <strong>to</strong> overcome<br />

discontinuous subnet issues. Whatever <strong>the</strong> reason, route<br />

redistribution is <strong>the</strong> process of having a routing pro<strong>to</strong>col distribute <strong>to</strong><br />

o<strong>the</strong>r members of its routing process domain routes that were learned<br />

from a source outside of <strong>the</strong> domain. Setting up route redistribution<br />

will be covered in Chapter 10, "Configuring IP Routing Pro<strong>to</strong>cols on<br />

Cisco Routers."<br />

TCP/IP Static Routing<br />

The battles over "Which is better, static or dynamically built routing<br />

tables?" will continue as long as <strong>the</strong>re is a choice. The decision is up <strong>to</strong><br />

<strong>the</strong> administra<strong>to</strong>r, because he or she has <strong>to</strong> live with whatever<br />

process is used <strong>to</strong> manage route collection. The idea of static routing<br />

is a very "IP-centric" concept. Most popular <strong>network</strong>ing pro<strong>to</strong>cols<br />

provide routing information dynamically and offer little or no manual<br />

manipulation of <strong>network</strong> routes. Static routing has strong benefits and,<br />

unfortunately, some strong weaknesses. The intent here is <strong>to</strong><br />

illustrate <strong>the</strong>m both so you have something <strong>to</strong> compare when you look<br />

at <strong>the</strong> dynamic routing pro<strong>to</strong>cols.<br />

Strengths of Static Routing<br />

Using static routes <strong>to</strong> manage a routing domain is a very popular thing<br />

<strong>to</strong> do. Dynamic routing pro<strong>to</strong>cols represent advanced TCP/IP<br />

knowledge <strong>to</strong> most people, so administra<strong>to</strong>rs who are new <strong>to</strong><br />

<strong>network</strong>ing tend <strong>to</strong> steer clear of <strong>the</strong>m. Most people who use TCP/IP<br />

have at least some experience with static routing in setting a default<br />

gateway. Lack of experience has perpetuated <strong>the</strong> use of static routing<br />

even in situations where it is not <strong>the</strong> best solution.<br />

There are five commonly acknowledged strengths of static routing:

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