nerdexam
Cisco

300-510 · Question #48

Refer to the exhibit. A network operator is getting the route for 10.11.11 0/24 from two upstream providers on #XR3. The network operator must configure #XR3 to force the 10.11.11.0/24 prefix to…

The correct answer is A. weight of 0 on the prefix coming from 192.168.0.2. In BGP, weight is a Cisco-proprietary attribute that is locally significant and used to prefer one path over another - higher weight wins. The operator wants to prefer the path via next-hop 10.0.0.9, which is learned from one provider. To deprioritize the competing path from…

Routing Policy and Manipulation

Question

Refer to the exhibit. A network operator is getting the route for 10.11.11 0/24 from two upstream providers on #XR3. The network operator must configure #XR3 to force the 10.11.11.0/24 prefix to route via next hop of 10.0.0.9 as primary when available. Which of these can the operator use the routing policy language for, to enforce this traffic forwarding path?

Exhibit

300-510 question #48 exhibit

Options

  • Aweight of 0 on the prefix coming from 192.168.0.2
  • Blower local preference on the prefix coming from 192.168.0.2
  • Chigher local preference on the prefix coming from 192.168.0.1
  • Dweight of 100 on the prefix coming from 192.168.0.1

How the community answered

(38 responses)
  • A
    82% (31)
  • B
    11% (4)
  • C
    5% (2)
  • D
    3% (1)

Explanation

In BGP, weight is a Cisco-proprietary attribute that is locally significant and used to prefer one path over another - higher weight wins. The operator wants to prefer the path via next-hop 10.0.0.9, which is learned from one provider. To deprioritize the competing path from neighbor 192.168.0.2, the operator sets a weight of 0 on that prefix in the routing policy applied to 192.168.0.2. This ensures the path from the other provider (leading to 10.0.0.9) wins the BGP path selection due to a higher weight. Setting a higher local preference on 192.168.0.1's path (C) would also work logically, but local preference is an iBGP attribute sent within the AS - it is less precise than weight for controlling a single router's preference. Weight of 100 on 192.168.0.1 (D) could work, but A is the minimal correct action given the answer key, ensuring the 192.168.0.2 path is deprioritized.

Topics

#BGP#Routing Policy#Path Attributes#Traffic Engineering

Community Discussion

No community discussion yet for this question.

Full 300-510 Practice