Skip to main content

 

A Quick Introduction to BGP

BGP, or Border Gateway Protocol, was created in the late 1980s by the Internet Engineering Task Force as a replacement for Interior Gateway Protocol (IGP) and Exterior Gateway Protocol (EGP). Its purpose is to connect different autonomous systems on the Internet. The first version, BGP-1, was defined in 1989 in a document called RFC 1105. The current version, BGP-4, was defined in 1995 in another document called RFC 1771.

BGP and IPv4 & IPv6

BGP, or Border Gateway Protocol, is responsible for distributing routing information for both IPv4 and IPv6 addresses. It is an exterior gateway protocol, which means that it is used to exchange routing information between different Autonomous Systems (ASes) and not within a single AS. BGP has two versions: iBGP (Internal BGP) for routers within the same AS and eBGP (External BGP) for routers in different ASes. eBGP is generally used between network Providers so that they can share or advertise routes between each other.

When to use BGP

BGP, or Border Gateway Protocol, is commonly used by service providers and large businesses to link their networks to the Internet or to establish multiple networks in a Virtual Private Network (VPN). It is also employed in data centers for connecting multiple locations or for ensuring redundancy. When selecting a routing protocol, it is important to evaluate the size and complexity of the network and the specific needs of the environment.

iBGP and eBGP

iBGP (Internal BGP) is utilized when all the routers are in the same Autonomous System. iBGB routers are not obligated to have a direct connection to each other, but they can use any internal IGP to establish communication. iBGP routers typically do not propagate routes learned from other iBGP routers to other iBGP routers, which helps prevent routing loops within an Autonomous System.

On the other hand, eBGP (External BGP) is used when routers are in different Autonomous Systems. eBGP routers must have a direct connection to exchange routing information. eBGP routers usually disseminate routes learned from other eBGP routers to all other eBGP routers.

More Reading 

For a more detailed write up on BGP and other Protocols like IS-IS and OSPF check out the following links on Web Review Star - A Review and Tech Site

An Introduction to BGP, including IPv4 and IPv6, iBGP and eBGP 

An Introduction to IS-IS Routing - Intermediate System to Intermediate System

Understanding the Benefits and Limitations of OSPFv3 Routing Protocol for Enterprise Networks

Understanding CIDR Notation - Address Allocation and Routing for IPv4 and IPv6 

And Lastly a guide to IPv6

The Complete Guide to Understanding IPv6 (Maybe not a "Complete guide" but a good start)


Labels:

Comments

Post a Comment

Popular posts from this blog

Setting up and Installing Rancid on FreeBSD for Cisco Products

Setting up and Installing Rancid on FreeBSD for Cisco Products What is Rancid? Rancid is an application that monitors a devices configuration including software and hardware. The configuration is then stored in a Concurrent Version System or CVS. Most of the time it is used to back up router, switch and firewall configurations, as well as notify you when a configuration has changed, i.e a firewall rule or a routers IP address or access list change. here is an example of the output =================================================================== retrieving revision 1.29 diff -u -4 -r1.29 mpls-jhb-pe1 @@ -288,9 +288,9 @@ ! interface Serial0/0 description Link to Client X bandwidth 2048 - ip address 192.168.1.244 255.255.255.254 + ip address 192.168.1.234 255.255.255.254 ip route-cache flow ip tcp header-compression iphc-format ip tcp compression-connections 256 ! ip ospf message-digest-key 1 md5 the - symbol represents what was removed the + symbol represents what was added The abo
2 comments
Read more

Tacacs+ Install and Config Guide

Tacacs+ Install and Config Guide What is TACACS As per wikipedia Terminal access controller access control system (TACACS) is a remote authentication protocol that is used to communicate with an authentication server commonly used in UNIX networks. TACACS allows a remote access server to communicate with an authentication server in order to determine if the user has access to the network. Installing Tacacs on FreeBSD This guide is intended to be a basic implementation of TACACS+, so although there are may features I am just going to document what I generally use. Please note that tac_plus is also available from Shrubbery Networks if you would like to install and configure on another platform. You may also want to check out my Rancid How-To Once again its in your ports directory. cd to /usr/ports/net/tac_plus4/ run a "make install clean" Once installed vi /usr/local/etc/rc.d/tac_plus.sh Then Change the following line from NO to YES tac_plus_enable=$ Save the file, then vi /e
Post a Comment
Read more

FreeBSD, Postfix, Mailscanner and Mailwatch Installation

Installing postfix, mailscanner and mailwatch on FreeBSD I have setup a number of servers using mailscanner and postfix to do antispam and antivirus checking. This particular example will show you how to set the server up as a mail gateway. i.e. all inbound and outbound mail will go via this server. You can also use the server as a pop3/imap4 server and doing so, does make life a little easier as you don't have to worry about the transport and relay_hosts files. At a later stage I will show that info too..... when I get a chance. This my seem strange but as there is quite a bit involved in installing and configuring I am splitting this into two How-To's this one, The install How-To and the configuration How-To First off its probably best to start on a new install of FreeBSD. Once you have done the initial portsnap fetch and portsnap extract Right here we go. Two things you might want to do is force your NIC to 100MB full duplex and install lsof Type in ifconfig and check if the
1 comment
Read more