Which TCP port does BGP use to establish a BGP session?
- 441
- 21
- 179
- 81
Explanation: Border Gateway Protocol (BGP) uses TCP port 179 as its transport mechanism. By using TCP, BGP ensures reliable connection-oriented delivery, which means the protocol does not need to implement its own error recovery or retransmission mechanisms.
A BGP speaker must establish a TCP session with its neighbor before any routing updates can be exchanged. Once this TCP relationship is formed, the neighbors can begin sending open messages and eventually exchange their routing tables via update messages. This reliance on TCP also allows BGP to scale effectively, as it can leverage the TCP sliding window mechanism to stream large amounts of routing data without waiting for an individual acknowledgment for every packet.
Related exam: Modules 8 – 13: Checkpoint Exam: Network Routing Answers (CCNP ENCOR v9)
