Refer to the exhibit. An engineer is troubleshooting a network routing issue on this IS-IS network situated at the customer's regional hub. Router 2 that runs Cisco IOS XR Software cannot see the…

Question

Exhibit

Options

• AOn router 1, remove the CISCOLIVE keyword after the IP router Isis command under interface
• BUnder the router isis command on router 1. Change is-type level-1 to is-type level-2.
• COn router 1, add the CISCOLIVE keyword after the IP router isis command under interface
• DUnder the router isis command on router 2. Change is-type level-1 to is-type level-2.

• A
  11% (3)
• B
  4% (1)
• C
  79% (22)
• D
  7% (2)

Explanation

In Cisco IOS (and IOS XE), IS-IS processes can be named, and the command to enable IS-IS on an interface is ip router isis [process-tag]. The process-tag (in this case 'CISCOLIVE') must match the tag used in the global router isis CISCOLIVE configuration block. If the interface on Router 1 has the ip router isis command without the CISCOLIVE tag - or is missing the tag - that interface is not associated with the correct IS-IS instance and will not participate in IS-IS adjacency formation on that process. As a result, the network 10.1.1.0/24 reachable via that interface will not be advertised. The fix is to add the CISCOLIVE keyword to the interface-level ip router isis command. Option A (removing the keyword) would make the association worse. Options B and D involve changing the IS-IS level type, which is unrelated to the instance-tagging issue described.

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