BGP Overview

Sumanta Das Gajendra Mahapatra

Content

1. Introduction

2. Session Establishment

3. Route processing

4. Basic Configuration

5. BGP Police

Introduction to BGP

- BGP : Broader Gateway Protocol

- Why Need BGP

Introduction to BGP

Introduction to BGP

Introduction to BGP

Introduction to BGP

BGP Characteristics :1. BGP is distance vector protocol with

enhancement - reliable update - Triggered updates only - Rich metrics (called path attributes)Designed to scale to huge internetworks

Introduction to BGP

IBGPEBGP

BGP Session Establishment

-Neighbor discovery - Hold Times-Keepalive

BGP Session Establishment

BGP Session Establishment

BGP Session Establishment

BGP Route Processing

BGP Route Processing

BGP Route Processing

Routing Loop:

IBGP: Split Horizon

EBGP: AS path info

Basic BGP Configuration

-Configuration command -Monitoring Command-Debug Command

Basic BGP Configuration

BGP Routing process :Router(config)#router bgp as-number

Configuring External Neighbors :Router(config-router)#neighbor ip-address remote-as as-number

To temporarily disable a BGP neighbor:Router(config-router)#neighbor ip-address shutdown

Configuring BGP Timers:Router(config-router)#timers bgp keepalive holdtime

Per Specific neighbor:Router(config-router)#neighbor [ ip address | peer group name ] timers keepalive holdtime

Basic BGP Configuration

Configuring MD5 Authentication:Router(config-router)#neighbor ip-address password string

Router(config-router)#no auto-summary

Aggregating BGP networksRouter(config-router)#aggregate-address address-prefix mask Router(config-router)#aggregate-address address-prefix mask

summary-only

Basic BGP Configuration

Basic BGP Configuration

BGP command for monitoring:

Monitorior neighber info:Router>show ip bgp summary

Monitor BGP neighbors on details:Router>show ip bgp neighbor ip-address

Monitor bgp table:Router > show ip bgp

Basic BGP Configuration

Debugging BGP :

Display all tcp transaction :

Router#debug ip tcp transactions

Display significant BGP event

Router#Debug ip bgp events

Debug BGp keepalive packets :

Router#debug ip bgp keepaklives

Display all incoming and outgoing BGp updates :

Router#debug ip bgp updates

BGP Policies

Needs of BGP policy

BGP Police

BGP Filters :

BGP Police

BGP Filters:

BGP Police

BGP Police

BGP Filters :

- As-Path Filters

- Prefix-List Filters

- Outbound Filters

- Route-Maps

BGP Police

BGP Filters :

- As-Path Filters

BGP Police

BGP Filters :

- As-Path Filters

Configuring BGP AS-Path Filters

Router(Config)#ip as-path access-list number permit | deny regexp

Router(Config-router)#neighbor ip-address filter-list as-path-filter in|out

BGP Police

BGP Filters :

- prefix-Based Filters

BGP Police

BGP Filters :

- prefix-Based Filters

Configuration:

router(config-router)#neighbor {ip address| peer-group-name } prefix-list list {in| out}

Router(config-routeer)#distribution-list prefix-list prefix-list out routing-process

BGP Police

BGP Filters :

- Outbound Router Filter

BGP Police

Outbound Router Filter ORF format

ORF message consist of the following fields

-AFI/SAFI

-ORF type

-When to refresh

-List of ORF entries

ORF entries depends on the ORF type

ORF capability needs to be negotiated for every supported ORF type

BGP Police

BGP Filters :

- Route-map BGP Filters :

BGP Police

BGP Filters :

- Route-map BGP Filters :

BGP Police

BGP Filters :

- Route-map BGP Filters :