JUNOS Enterprise Routing

Chapter Review Answers

1. Answer: B. Only Anycast-RP allows multiple RPs to be active at the same time for the same group.

2. Answer: C. The BSR mechanism automatically balances, on a group-range basis, among a set of C-RPs using a distributed hash function.

3. Answer: B. PIM bootstrap policy can be used to filter BSR messages being sent or received. Using PIMv1 also blocks BSR, as it is not supported in that version.

4. Answer: C. Sparse-dense operation defaults to sparse mode, except for groups explicitly designated as dense.

5. Answer: A. PIM register policy allows filtering of registers at the first hop, or at the RP, which controls the number of sessions on the RP.

6. Answer: B. The last hop router is in charge of making the switch from RPT to SPT, and in JUNOS software this occurs upon receipt of the first packet.

7. Answer: B. The show multicast route command displays dynamic data plane state that results from multicast traffic. Join-related commands show control plane state.

8. Answer: D. All of the operations described are based on an RPF check.

9. Answer: D. Anycast-RP requires a shared, and unique, lo0 address; the unique address is used for RP-RP communication.

10. Answer: E. This is a multicast route, in the data plane, which is created when allowed by join state and when data activity occurs. This is an (S,G) entry, and therefore it is not on the RPT.

11. Answer: B. IGMPv3 supports v2’s group leave as well as SSM.

12. Answer: D. A group query is sent to the multicast address of the group itself.