July 2003
Intermediate to advanced
908 pages
25h 3m
English
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Chapter 19. Access Lists
19.0. Introduction
An Access Control List (ACL) is generically a method for doing pattern matching based on protocol information. There are many reasons for doing this type of pattern matching, such as restricting access for security reasons or restricting routing tables for performance reasons.
Cisco has several different general kinds of access lists. The most common are the numbered ACLs, which are summarized in Table 19-1. But there are also named access lists, reflexive access lists, context-based access lists, and rate-limit access lists. There are even timed access lists that can have different effects at different times of day, although we will not cover them in this book. Within each of these general categories, there are many different types of ACLs that match on different protocol information. When working with route filtering, it is often easiest to work with prefix lists, which are another type of ACL discussed in more detail in Chapters Chapter 6, Chapter 7, Chapter 8, and Chapter 9.
You can apply an ACL in many different ways. Applied to an interface, you can use it to accept or reject incoming or outgoing packets based on protocol information such as source or destination address, port number, protocol number, and so forth. Applied to a routing protocol, this same ACL might prevent the router from sharing information about a particular route. And, applied to a route map, the ACL could just identify packets that need to be tagged or treated differently. ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.