OSPF is imported into BGP through the import-route command. Which of the following descriptions is correct?

Question

Options

• AThe imported command can only import IGP routes and static routes into BGP
• BBy default, the Origin attribute imported route is IGS
• CWhen the imported routing protocol is IS-IS, the process number must be specified
• DImport-route cannot cooperate with route-policy to filter routes imported into BGP by other routing protocols

• A
  6% (2)
• B
  3% (1)
• C
  77% (24)
• D
  13% (4)

Explanation

Option C is correct because IS-IS supports multiple process instances running simultaneously on a single device, so when using import-route to pull IS-IS routes into BGP, the router cannot assume which IS-IS process to reference - the process number is mandatory to remove that ambiguity. Other protocols like OSPF also use process IDs, but IS-IS is the protocol specifically called out in Huawei documentation as requiring explicit process specification in this context.

Option A is wrong because import-route can also import directly connected routes (direct) into BGP, not just IGP and static routes. Option B is wrong because "IGS" is not a valid BGP Origin attribute value at all - the three valid values are IGP (i), EGP (e), and Incomplete (?), and routes imported via import-route receive the Incomplete (?) origin by default, not IGP. Option D is wrong because import-route absolutely can cooperate with a route-policy; you can append a route-policy clause to the import-route command to filter or modify routes before they enter BGP.

Memory tip: Think of IS-IS as the one IGP that demands you "identify yourself completely" - because multiple IS-IS processes can coexist, you must always name the process number, or the command is rejected.

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