A quick post about one of the key pieces of information that any potential CCIE has to know in-depth; how does BGP select a path?
I have put together a large but informative flow chart that details what happens:
Click here to download a larger version of the image
I had come across this link on the internet but needed something with a bit more detail on it so I decided to ‘make my own’
The flow chart is based on information within Jeff Doyle’s ‘Routing TCP/IP, Volume 2’ and this link:
BGP Best Path Selection Algorithm
Creating the document has really helped to etch the order in my mind J
BGP won’t consider any of the above unless the next-hop is considered reachable
By: Fred Bloggs on February 27, 2008
at 6:23 pm
A valid point, I have made a presumption that the next hop is always available but I will amend the flow chart to represent your comment.
Many thanks
By: Richard @ Configureterminal.com on February 27, 2008
at 6:35 pm
Very helpful, thanks!
I’ve downloaded a copy to use for my SP exam.
By: bitbucket on February 27, 2008
at 9:52 pm
[...] found this great link from Richard Bannister’s CCIE Blog. Richard has put together a great BGP Best Path Selection flow chart that details the order in which a path is chosen. Great [...]
By: BGP Best Path Selection Algorithm | ardenpackeer.com on June 24, 2008
at 10:40 am
Hi Richard,
Just to inform you that chaeplin link is broken in the end of your article.
Nice chart, well done!
By: pello on August 22, 2008
at 9:50 am
Hi Pello,
Thanks for letting me know, luckily I had a copy saved locally on my laptop so I have uploaded it to http://rbcciequest.wordpress.com/files/2008/08/bgp_pathselection.jpg
Nice OSPF MD5-Auth hack by the way.
Thanks again
Richard
By: Richard @ Configureterminal.com on August 22, 2008
at 12:22 pm
really a awesome post.
regards
shivlu jain
By: shivlu jain on February 2, 2009
at 10:37 am
Cool. Thank you very much, very useful. Added a reference in my blog to this post
By: Nicolas on May 20, 2009
at 10:03 pm
[...] A nice chart illustrating the BGP bestpath selection process. [...]
By: 111 Articles to Help You Pass the CCIE Routing and Switching Lab Exam on October 21, 2009
at 3:00 pm