An engineer is implementing MPLS OAM to monitor traffic within the MPLS domain. Which action must the engineer perform to prevent packets from being forwarded beyond the service provider domain when the LSP is down?
A.
Configure a private IP address as the destination address of the headend router of Cisco MPLS TE.
B.
Disable IP redirects only on outbound interfaces.
C.
Disable IP redirects on all ingress interfaces.
D.
Implement the destination address for the LSP echo request packet in the 127.x.y.z/8 network.
Actually the engineer needs to do nothing to prevent this because if not mentioned the destionation address is from 127./8 range, so it is prevented by default.
A is not right because:
Router#ping mpls ipv4 2.2.2.2/32 destination 10.0.0.1
% Destination address must be a 127.x.y.z address
10.0.0.1 is an invalid address
Router#
D is correct see below:
"The source address of the LSP echo request is the IP address of the LDP router generating the LSP request.
The destination IP address is a 127.x.y.z/8 address, which prevents the IP packet from being switched to its
destination if the LSP is broken. The 127.0.0.x destination address range prevents the OAM packets from
exiting the egress provider-edge router, which keeps them from leaking from the service-provider network
to the customer network."
https://www.cisco.com/c/en/us/td/docs/wireless/asr_901s/scg/b_scg_for_asr901s/b_scg_for_asr901s_chapter_010001.pdf
The source address of the LSP echo request is the IP address of the LDP router generating the LSP request.
The destination IP address is a 127.x.y.z/8 address, which prevents the IP packet from being switched to its
destination if the LSP is broken. The 127.0.0.x destination address range prevents the OAM packets from
exiting the egress provider-edge router, which keeps them from leaking from the service-provider network
to the customer network.
https://www.cisco.com/c/en/us/td/docs/wireless/asr_901s/scg/b_scg_for_asr901s/b_scg_for_asr901s_chapter_010001.pdf
D is correct
https://www.cisco.com/c/en/us/td/docs/routers/asr9000/software/asr9k-r7-5/mpls/configuration/guide/b-mpls-cg-asr9000-75x/implementing-mpls-oam-74x.html
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