BGP Series 6: BGP AS-Path Attribute

BGP AS-Path Attribute:

• This attribute is used to decide the best-path for a certain prefix.

• By default, if a bgp router gets two or more updates for the same prefix, then, it will decide at the best path by simply looking at the AS-path attribute...ie. which of these routes went through the fewest number of AS and whichever route had the lowest number (quantity, not value) of AS-path, that is the best route

BGP Series 5: BGP Neighbor States, Message Types, BGP Table and Verification Commands

BGP Neighbor States:

• Idle: bgp process is not even active. Could be due to bgp being administratively shut (or) no route to neighbor in routing table [most likely]
• Connect: [very rarely seen] bgp is waiting for tcp connection to be completed

BGP Series 4: Intro to BGP, BGP Commands, AS-path, ISP, eBgp Requirements, update-source and multi-hop, iBGP Requirements

BGP Series 4

BGP Intro:

• BGP formed on Port 179.
• BGP rides on top of TCP.
• iBGP or eBGP is automatically decided by bgp based on our asn and the asn mentioned in the neighbor command
• There is a lot of differences between the capabilities and functiona lities offered by both iBGP and eBGP
• RFC 1771 is the RFC for bgp