Border Gateway Protocol (BGP4)

6/12/03


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Table of Contents

Border Gateway Protocol (BGP4)

Border Gateway Protocol (BGP4)

BGP Part 1

Routing versus Forwarding

IP Routing

IP Routing

IP routing

IP route lookup

IP route lookup: Longest match routing

IP route lookup: Longest match routing

IP route lookup: Longest match routing

IP route lookup: Longest match routing

IP route lookup: Longest match routing

Dynamic Routing

Forwarding Table/FIB

Routing Tables Feed the Forwarding Table

Building Blocks

Autonomous System (AS)

Autonomous System (AS)...

Routing flow and packet flow

Egress Traffic

Ingress Traffic

Types of Routes

What is Policy?

Interior vs. Exterior Routing Protocols

Hierarchy of Routing Protocols

DeMarcation Zone (DMZ)

Addressing – ISP

BGP Part 2

BGP Basics

Protocol Basics

Protocol Basics

Terminology

Terminology

BGP Basics …

BGP Peers

BGP Peers

BGP Peers

Configuring BGP Peers

Configuring BGP peers

Configuring BGP peers

Configuring BGP peers

Configuring BGP peers

Configuring BGP peers

Configuring BGP peers

BGP Update Messages

BGP Updates — NLRI

BGP Updates — Attributes

AS-Path Attribute

Next Hop Attribute

Next Hop Attribute

Next Hop Attribute

Next Hop Attribute (more)

BGP Updates – Withdrawn Routes

BGP Updates – Withdrawn Routes

BGP Routing Information Base

BGP Routing Information Base

BGP Routing Information Base

BGP Routing Information Base

BGP Routing Information Base

BGP Routing Information Base

An Example…

BGP Part 3

Basic BGP commands

Inserting prefixes into BGP

“redistribute static”

“redistribute static”

“network” command

Aggregates and Null0

Stable iBGP peering

BGP Part 4

BGP Path Attributes: Why ?

BGP Path Attributes...

AS-PATH

AS-Path

Next-Hop

Third Party Next Hop

Next Hop...

Local Preference

Local Preference

Multi-Exit Discriminator

Multi-Exit Discriminator (MED)

Origin

Communities

Communities

Weight

Administrative Distance

Synchronization

Synchronization

BGP route selection (bestpath)

BGP route selection (bestpath)

BGP route selection (bestpath)

BGP Route Selection...

BGP Part 5

PPT Slide

Filter list rules Regular Expressions

Filter list – using as-path access list

Policy Control – Prefix Lists

Prefix Lists – Examples

Prefix Lists – More Examples

Policy Control Using Prefix Lists

Policy Control – Route Maps

Route-map match & set clauses

Route Map: Example One

Route Map: Example Two

BGP Part 6

PPT Slide

Stub AS

PPT Slide

Multi-homed AS

Service Provider Network

Common Service Provider Network

Load-sharing – single path

Load-sharing – multiple paths from the same AS

Redundancy – Multi-homing

Default from all providers

Default from all providers

Customer prefixes plus default from all providers

Customer routes from all providers

Full routes from all providers

Full routes from all providers

Best Practices IGP in Backbone

Best Practices... Connecting to a customer

Best Practices... Connecting to other ISPs

Best Practices... The Internet Exchange

Summary

Author: Philip Smith, Abha Ahuja

Home Page: http://www.ws.afnog.org

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