350-401 · Question #917
Refer to the exhibit. Which configuration must be applied to ensure that the preferred path for traffic from AS 65010 toward AS 65020 uses the R2 to R4 path?
The correct answer is B. R2(config)# router bgp 65010. To ensure R2 prefers the R2 to R4 path for traffic destined to AS 65020, configuring a higher BGP weight on R2 for its neighbor R4 is the appropriate action.
Question
Refer to the exhibit. Which configuration must be applied to ensure that the preferred path for traffic from AS 65010 toward AS 65020 uses the R2 to R4 path?
Exhibits
Options
- AR4(config)# router bgp 65020
- BR2(config)# router bgp 65010
- CR2(config)# router bgp 65010
- DR4(config)# router bgp 65020
How the community answered
(32 responses)- A3% (1)
- B78% (25)
- C6% (2)
- D13% (4)
Why each option
To ensure R2 prefers the R2 to R4 path for traffic destined to AS 65020, configuring a higher BGP weight on R2 for its neighbor R4 is the appropriate action.
Configuring weight on R4 (in AS 65020) for its neighbor R2 (in AS 65010) would influence R4's outbound path preferences to AS 65010, not AS 65010's outbound preferences to AS 65020.
The BGP weight attribute is Cisco-proprietary and local to the router where it is configured; a higher weight is always preferred. By setting neighbor 10.10.10.4 weight 500 on R2, R2 will locally assign a higher preference to routes learned from R4, thereby choosing the R2 to R4 path for outbound traffic to AS 65020.
While local-preference could also be used to influence outbound traffic for an entire AS, it would typically be configured to be distributed internally; weight takes precedence over local-preference in the BGP best path selection algorithm on R2 itself, making it a local decision.
Configuring local-preference on R4 (in AS 65020) for its neighbor R2 would influence how routers in AS 65020 prefer paths to AS 65010, not how AS 65010 prefers paths to AS 65020.
Concept tested: BGP path attribute manipulation (Weight)
Source: https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13761-4.html
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