350-501 · Question #88
Refer to the exhibit. A network engineer is implementing a BGP protocol. Which effect of the local-as keyword in this configuration is true?
The correct answer is D. It enables peer 192.168.1.2 to establish a BGP relationship with R1 using AS 65112 without. The "local-as 65112 no-prepend replace-as" command on R1 configures R1 to present itself as AS 65112 to its peer 192.168.1.2, without prepending this local AS to outgoing updates, while expecting the peer to be in AS 65012.
Question
Refer to the exhibit. A network engineer is implementing a BGP protocol. Which effect of the local-as keyword in this configuration is true?
Exhibit
Options
- AIt enables peer 192.168.1.2 to establish a BGP relationship with R1 using AS 65012 and the
- BIt enables peer 192.168.1.2 to establish a BGP relationship with R1 using AS 65012 without
- CIt enables peer 192.168.1.2 to establish a BGP relationship with R1 using AS 65112 and the
- DIt enables peer 192.168.1.2 to establish a BGP relationship with R1 using AS 65112 without
How the community answered
(48 responses)- A4% (2)
- B17% (8)
- C8% (4)
- D71% (34)
Why each option
The "local-as 65112 no-prepend replace-as" command on R1 configures R1 to present itself as AS 65112 to its peer 192.168.1.2, without prepending this local AS to outgoing updates, while expecting the peer to be in AS 65012.
The `no-prepend` option explicitly prevents R1's local AS 65112 from being prepended to the AS path.
The local AS is 65112, not 65012. The `remote-as` is 65012.
The `no-prepend` option prevents AS 65112 from being prepended.
The `local-as 65112 no-prepend replace-as` command configures the BGP router (R1) to use AS 65112 for the local-as in its BGP updates to peer 192.168.1.2, but the `no-prepend` option prevents AS 65112 from being prepended to the AS path for outgoing advertisements, and `replace-as` is typically used for AS Path manipulation. The `remote-as 65012` still means R1 expects its peer 192.168.1.2 to belong to AS 65012. Therefore, it enables a BGP relationship with peer 192.168.1.2 (which is in AS 65012) while presenting R1's local AS as 65112 without prepending it.
Concept tested: BGP local-as command options
Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_bgp/configuration/15-mt/irg-15-mt-book/irg-conf-bgp.html
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