December 2001
Intermediate to advanced
608 pages
25h 14m
English
Content preview from CISCO IOS in a NutshellBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Chapter 10. Border Gateway Protocol
Fortunately, this is a Nutshell book, so I don’t have to do anything more than give a brief introduction to the Border Gateway Protocol (BGP), one of the most complex topics in network routing. Covering BGP in any detail could easily require hundreds of pages. Unlike the other routing protocols we’ve discussed, BGP is an exterior routing protocol, which means it routes traffic between different autonomous systems. Its primary use is on the Internet backbone; it shouldn’t be used on most networks that are connected to the Internet. However, if you have more than one Internet service provider or your network is multihomed, you must use BGP.
BGP is a successor to EGP, which had many limitations. BGP’s main new feature was Classless Interdomain Routing (CIDR), which rescued the almost-exhausted Internet IP address space. The current version of BGP is BGP4; it’s unlikely that you’ll need to know about earlier versions.
Introduction to BGP
We can run two types of BGP routing on our network:
- Internal BGP (iBGP)
iBGP exchanges BGP information within an autonomous system. Internal BGP sounds counterintuitive, since BGP is supposed to be an “external” routing protocol. The point of internal BGP is to distribute your BGP information between your external BGP routers. Your external routers are usually not close together; iBGP allows them to communicate across your internal network.
iBGP is necessary in networks that have multiple paths to the Internet. It provides ...
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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.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
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.