What is a valid BGP neighbor state?
Click on the arrows to vote for the correct answer
A. B. C. D.C
BGP (Border Gateway Protocol) is a routing protocol used to exchange routing information between different autonomous systems (AS) on the Internet. In BGP, a neighbor is a router with which BGP is configured to exchange routing information. BGP neighbor state refers to the state of the connection between two BGP routers.
The BGP neighbor state machine is defined in the RFC 4271. It consists of six different states, which are as follows:
Idle: This is the initial state of a BGP neighbor. In this state, the BGP router is waiting for a TCP connection to be established with its neighbor.
Connect: In this state, the BGP router is attempting to establish a TCP connection with its neighbor.
Active: In this state, the BGP router is actively trying to establish a TCP connection with its neighbor.
OpenSent: In this state, the BGP router has sent an OPEN message to its neighbor and is waiting for a response.
OpenConfirm: In this state, the BGP router has received an OPEN message from its neighbor and is waiting for a KEEPALIVE or NOTIFICATION message.
Established: In this state, the BGP router has successfully established a TCP connection with its neighbor, exchanged OPEN messages, and is exchanging routing information.
Now, let's look at the options given in the question:
A. OpenEstablished: This is not a valid BGP neighbor state. It seems to be a combination of two different BGP states, OpenSent and Established.
B. OpenConnect: This is not a valid BGP neighbor state. There is no state in the BGP neighbor state machine called "Connect" or "OpenConnect".
C. OpenConfirm: This is a valid BGP neighbor state. In this state, the BGP router has received an OPEN message from its neighbor and is waiting for a KEEPALIVE or NOTIFICATION message.
D. OpenActive: This is a valid BGP neighbor state. In this state, the BGP router is actively trying to establish a TCP connection with its neighbor.
Therefore, the correct answer is either C or D, depending on the context of the question.