Free H12-821_V1.0 Questions Attempt

In the topology, SWB ' s GE0/0/2 is the Root Port because it has the least cost path to the Root Bridge (SWA). SWC ' s GE0/0/1 is the Designated Port because it forwards traffic to SWA while maintaining the shortest path to the Root Bridge. This setup ensures efficient traffic flow in the spanning tree topology ​.

Routing Entries in PIM

(S, G) entries : Represent the shortest path tree (SPT) from a specific source ( S ) to a specific multicast group ( G ). These entries are created after data packets are transmitted directly from the source to the receivers.

(S, G) entries are used in both PIM-DM and PIM-SM modes.

PIM-DM and PIM-SM Modes

In PIM-DM , multicast traffic is initially flooded throughout the network and pruned where no receivers exist. (S, G) entries represent source-specific paths created after the flooding stage.

In PIM-SM , multicast traffic initially flows through a shared tree, but (S, G) entries are created when the network switches to the SPT for more efficient forwarding.

HCIP-Datacom-Core Reference

The functionality and application of (S, G) routing entries are detailed in multicast and PIM configuration chapters​​.

Comprehensive and Detailed In-Depth Explanation:

Source-Specific Multicast (SSM) uses (S, G) addressing instead of the traditional (*, G) used in Any-Source Multicast (ASM) .

IGMP SSM Mapping is used to enable IGMPv1 and IGMPv2 hosts (which do not support explicit source selection) to work in an SSM environment by mapping (*, G) to (S, G) .

A. TRUE → The mapping allows IGMPv1/v2 to function in an SSM network .

B. TRUE → IGMPv3 natively supports SSM , so SSM mapping is not needed for IGMPv3 .

C. FALSE → The SSM address range is 232.0.0.0/8 in IPv4 , but this is not the only range used for SSM globally .

D. TRUE → If IGMP SSM mapping is disabled, IGMPv1/v2 cannot work in an SSM network because they do not support explicit source selection .

???? Reference: Huawei HCIA-Datacom Study Guide, IGMP Versions and SSM Mapping.