Which port number is used by the Border Gateway Protocol (BGP) for routing updates?

Which port number is used by the Border Gateway Protocol (BGP) for routing updates?

• A. 548
• B. 67
• C. 179
• D. 13

Answer: (C)

BGP relies on TCP for reliable delivery of its routing updates, and it uses a fixed, well-known port for those TCP sessions. That port is 179, assigned specifically for BGP. When two BGP speakers establish a session to exchange updates, they connect to the neighbor’s IP on port 179, then exchange OPEN, UPDATE, KEEPALIVE, and NOTIFICATION messages over that TCP connection. Other port numbers belong to different services (for example, 67/68 for DHCP, 13 for daytime, 548 for Apple Filing Protocol), so they aren’t used for BGP.

BGP relies on TCP for reliable delivery of its routing updates, and it uses a fixed, well-known port for those TCP sessions. That port is 179, assigned specifically for BGP. When two BGP speakers establish a session to exchange updates, they connect to the neighbor’s IP on port 179, then exchange OPEN, UPDATE, KEEPALIVE, and NOTIFICATION messages over that TCP connection. Other port numbers belong to different services (for example, 67/68 for DHCP, 13 for daytime, 548 for Apple Filing Protocol), so they aren’t used for BGP.