BGP CHAPTER 1- CONCEPT

Introduction

• Biggest Routing Protocol
• Most Complex Routing Protocol 
• Need to have lot of Patience 
• Can’t compare with IGPs – RIP ,EIGRP,OSPF etc.
• BGP – FLOW CONTROL 
• Route Manipulation 
• Can Handle Huge Routing Table
• A.K.A ROUTING PROTOCOL OF INTERNET 
• Exterior Gateway Protocol (EGP) – Runs between Autonomous System
• Uses TCP Port 179

Internet 

Network of Networks
Global Routing Table –HUGE SIZE

GRT

GRT

Types of Service Provider

Tier 1 – Major SP
Tier 2 and 3 Service Provider
Transit
Peering and Uplink

ISP TIER ARCHITECTURE

Autonomous System (AS)

An Autonomous System (AS) is a group of networks under a single administrative control.
An AS can be Internet Service Provider (ISP) or a large Enterprise Organization.
IGP operates (handles routing) within AS.  IGPs include RIP, IGRP, EIGRP, and OSPF.
EGP operates (handles routing) between AS .BGP is the only EGP

Autonomous System Number (ASN) - 16 bit binary number & we can represent (2 16) numbers, which is equal to 65536 in decimals.
Range of ASN – 0 to 65535
0 , 65535 - Reserved
1 – 64511 - Internet Routing – ISP AS
64512 – 65534 Private Use - Private AS

List of Autonomous System (AS)

http://www.bgplookingglass.com/list-of-autonomous-system-numbers

Where BGP IS USED  ?

ISP's –Internet Service Providers
 Large enterprises

BGP AD VALUES

EBGP = 20
IBGP = 200
IBGP can run on Indirectly connected Routers
IBGP DEPENDS UPON OTHER IGP
EGBP directly connected neighbors                                                                                                                                   

BGP IS SLOWEST !!!!!

Convergence is Very Slow

Timers – Hello – 60 Secs and Dead – 180 Secs

Thanks for Reading !!!!