Discuss Juniper JN0-281 Exam Topic 4 Question 9

You are troubleshooting a downed BGP session.

Referring to the exhibit, what is the cause of the problem?

AThe UDP session between the peers has not been established.

BThe local peer has sent an Open message but not received one from the remote peer.

CThe TCP session between the peers has not been established.

DThe local peer has sent an Update message but not received one from the remote peer.

Suggested Answer: C

The BGP session in the exhibit shows the state as Connect, which indicates that the TCP session between the BGP peers has not been fully established.

Step-by-Step Breakdown:

BGP State 'Connect':

The Connect state is the second stage in the BGP finite state machine (FSM). At this stage, BGP is trying to establish a TCP session with the peer, but the session has not yet been successfully established.

A successful TCP three-way handshake (SYN, SYN-ACK, ACK) is required before BGP can progress to the OpenSent state, where the peers exchange BGP Open messages.

Possible Causes:

A firewall blocking TCP port 179.

Incorrect IP addresses or network connectivity issues between the BGP peers.

Juniper Reference:

BGP Troubleshooting: In Junos, if a BGP session is stuck in the Connect state, the issue is likely due to a failure in establishing the underlying TCP connection.

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26 comments · newest first

Elmira 10 months ago

C makes the most sense to me.

Mel 10 months ago

Definitely B, the Open message issue is common.

Emerson 11 months ago

I thought it was A at first, but now I'm not so sure.

Ciara 11 months ago

Wait, how can we be sure it's not D?

Carma 11 months ago

Looks like the TCP session isn't up.

Sylvie 11 months ago

I thought the Update message was sent after the session was established, so option D seems unlikely to me. I guess it’s probably about the Open message or the TCP session.

Olen 11 months ago

I feel like the UDP session isn't really relevant for BGP, so I doubt it's option A. But I could be wrong about that.

Pura 12 months ago

I practiced a similar question where the local peer didn't receive an Open message. That makes me lean towards option B, but I could be mixing it up.

Amber 12 months ago

I remember something about BGP sessions needing a TCP connection, so I think it might be option C, but I'm not entirely sure.

Willie 1 year ago

Okay, I think I've got it. The session is in the "Idle" state, which means the TCP connection hasn't been established. So the correct answer must be option C.

Antonette 1 year ago

The question is asking about the cause of the problem, and the options mention things like UDP, Open messages, and Update messages. I'm a bit confused - I'll need to think this through step-by-step.

Nina 1 year ago

Hmm, the exhibit shows a BGP session in the "Idle" state, so I'm guessing the TCP session between the peers hasn't been established. I'll go with option C.

Demetra 1 year ago

This looks like a tricky BGP troubleshooting question. I'll need to carefully review the exhibit and options to determine the root cause.

Loren 1 year ago

Hah, UDP session? What is this, a joke? Nah, it's gotta be the TCP session. Can't have a BGP party without the proper handshake, am I right?

Lauran 1 year ago

Hmm, I'm going with C. The exhibit clearly shows the connection status as 'Idle', which means the TCP session hasn't been established. Simple stuff, really.

Louis 1 year ago

↳ replying to Lauran

C) The TCP session between the peers has not been established.

Gretchen 1 year ago

↳ replying to Lauran

B) The local peer has sent an Open message but not received one from the remote peer.

Lavera 1 year ago

↳ replying to Lauran

A) The UDP session between the peers has not been established.

Marlon 1 year ago

I disagree with Emilio, the TCP session between the peers has not been established.

Emilio 1 year ago

I believe option C is the cause of the problem.

Genevive 1 year ago

I agree with Leana, the local peer has sent an Open message but not received one from the remote peer.

Sherrell 1 year ago

The TCP session between the peers has not been established. That's gotta be it. I mean, how else are they gonna talk if they can't even connect in the first place?

Louisa 1 year ago

↳ replying to Sherrell

C) The TCP session between the peers has not been established.

Aja 1 year ago

↳ replying to Sherrell

B) The local peer has sent an Open message but not received one from the remote peer.

Maryann 1 year ago

↳ replying to Sherrell

A) The UDP session between the peers has not been established.

Leana 1 year ago

I think the cause of the problem is option B.

Juniper JN0-281 Exam - Topic 4 Question 9 Discussion