300-410 Question 139
Select 2A network engineer is configuring a BGP session between two routers that are not directly connected. The routers belong to two different Autonomous Systems (AS), and the engineer must ensure that the BGP session is established successfully. Which of the following configurations are required to meet this objective?
- A
Enable BGP multihop on both routers
- B
Configure a 4-byte AS number on both routers
- C
Use the 'next-hop-self' command on both routers
- D
Ensure proper BGP neighbor authentication using a password
- E
Disable synchronization on both routers
Show answer and explanation
Correct answers: A, D
Explanation
To establish a BGP session between non-directly connected routers, enabling multihop is critical to accommodate the TTL value across intermediate hops. Additionally, securing the session with proper neighbor authentication ensures the integrity of the BGP connection. Other options, such as 4-byte AS configuration, next-hop-self, and synchronization, are not directly required for establishing a basic multihop BGP session.
- A. Correct.
Enabling BGP multihop is necessary for establishing a BGP session between routers that are not directly connected, as it allows the TTL value to be incremented.
- B. Incorrect.
Using a 4-byte AS number is only required if the AS numbers exceed the 16-bit space. It is not mandatory for establishing a multihop BGP session.
- C. Incorrect.
The 'next-hop-self' command is used to modify the next-hop attribute for routes advertised to a neighbor. It is not required for establishing a BGP session.
- D. Correct.
BGP neighbor authentication ensures that the connection is secure and prevents unauthorized BGP sessions.
- E. Incorrect.
Disabling synchronization is related to BGP route propagation in older configurations and is not a requirement for establishing a neighbor relationship.