300-510 · Question #267
Refer to the exhibit. The network is situated at different locations on the customer site. The customer runs a mission-critical application behind CE2, which is connected over a 10 GB link to the…
The correct answer is B. Change the subnet mask on the PE2 loopback interface from /24 to /32. The PE2 loopback address (33.33.33.1) is being used as the LDP (Label Distribution Protocol) router ID. The subnet mask for the loopback interface is /24, causing issues with label allocation and distribution. MPLS LDP requires loopback interfaces to be configured with a /32…
Question
Refer to the exhibit. The network is situated at different locations on the customer site. The customer runs a mission-critical application behind CE2, which is connected over a 10 GB link to the local network of the customer. After recent configuration changes to the P and PE routers, an LSP failure has occurred, causing connectivity issues. CE1 is unable to reach the CE2 internal IP address. Which action resolves this issue?
Exhibit
Options
- AConfigure the ip ospf network point-to-point command on PE2.
- BChange the subnet mask on the PE2 loopback interface from /24 to /32.
- CConfigure the ip ospf network point-to-multipoint command on PE2.
- DImplement BGP in the core and configure an MPLS TE tunnel between PE1 and PE2.
How the community answered
(23 responses)- A9% (2)
- B74% (17)
- C13% (3)
- D4% (1)
Explanation
The PE2 loopback address (33.33.33.1) is being used as the LDP (Label Distribution Protocol) router ID. The subnet mask for the loopback interface is /24, causing issues with label allocation and distribution. MPLS LDP requires loopback interfaces to be configured with a /32 mask to uniquely identify routers and ensure proper label distribution. Changing the PE2 loopback address mask to /32 ensures it is uniquely advertised and reachable throughout the MPLS core. This allows the correct label (33.33.33.1/32) to be bound and distributed, fixing the LSP issue and restoring end-to-end connectivity.
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