How BGP initiate TCP connection to the BGP peer?

[rookie R]

Dear All,

How to initiate a TCP connection to the BGP peer? Is 'listen at port 179 to open it up' is one of it?

Please help. Thank you!

[Giuseppe Larosa]

Hello @rookie R ,

actually both sides both peers can initiate a TCP connection to well known port TCP 179.

However, only one TCP session is needed and the "server" side TCP 179 is taken by the BGP peer with the highest IP address.

So at the same time a BGP router can act as "server" on one eBGP session and as "client" in another one.

see the following article by Ciscopress

https://www.ciscopress.com/articles/article.asp?p=2756480&seqNum=4

Hope to help

Giuseppe

[Georg Pauwen · Accepted solution]

Hello,

have a look at the link below for a detailed explanation.

https://packetpushers.net/demystifying-bgp-session-establishments/