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

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 IBGP EBGP

BGP Session Establishment -Neighbor discovery - Hold Times -Keepalive

BGP Session Establishment

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 networks Router(config-router)#aggregate-address address-prefix mask Router(config-router)#aggregate-address address-prefix mask summary-only

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 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 :