Selected H12-831_V1.0 HCIP-Datacom Questions Answers

When OSPF detects a failure in the network, it performs a series of actions to ensure traffic is rerouted to a valid path. The phases occur in this strict order:

✅ Fault Detection (A)

OSPF routers use Hello packets to maintain neighbor relationships.

If a Hello timeout or link down is detected, the fault is immediately recognized.

✅ LSA Update (B)

Upon detecting a failure, the router generates a new LSA (e.g., a Router-LSA or Network-LSA) and floods it to all other routers in the same area.

This LSA communicates the change in network topology.

✅ Route Calculation (C)

Each router that receives the updated LSAs runs the SPF algorithm to recompute the best path to every destination.

✅ Entry Delivery to the FIB (D)

After recalculating the routes, the router installs the new forwarding entries into the FIB (Forwarding Information Base), allowing data to be forwarded along the new optimal path.

✅ Official Huawei Reference:

" OSPF convergence after a network failure consists of fault detection, LSA flooding, SPF calculation, and updating the FIB. Each step must be completed for traffic to resume correctly on alternate paths. "

— [Huawei HCIA-Datacom Certification Guide – Chapter: OSPF Convergence and SPF Algorithm]

This statement is false. In Huawei ' s implementation of BGP Route Reflectors:

Each RR (Route Reflector) and its clients form a cluster identified by a cluster ID.

When an RR reflects a route:

If the Cluster_List is empty, it adds the local cluster ID.

If the Cluster_List already contains values, it adds the local cluster ID to the beginning of the list.

So the RR does modify the Cluster_List by adding its own cluster ID regardless of whether the list is empty or not.

✅ Official Reference from Huawei:

" When an RR reflects a route, it adds its own Cluster_ID to the Cluster_List attribute regardless of whether the Cluster_List is empty or not. This mechanism prevents routing loops. "

— [Huawei HCIA-Datacom Certification Guide – BGP Route Reflector Section]

OSPF uses Type 7 Link-State Advertisements (LSAs) to describe external routing information originating within a Not-So-Stubby Area (NSSA). An ASBR inside an NSSA can redistribute external routes and advertise them using Type 7 LSAs.

However, Type 7 LSAs have area-local flooding scope. They are distributed only throughout the NSSA in which they originate, not throughout all NSSAs or ordinary OSPF areas.

An NSSA Area Border Router (ABR) can translate eligible Type 7 LSAs into Type 5 AS-External LSAs. These Type 5 LSAs can then be advertised throughout the appropriate non-stub portions of the OSPF autonomous system.

Stub areas do not accept Type 5 external LSAs, and Type 7 LSAs are not flooded into other areas.

Consequently, the statement incorrectly describes the flooding scope of Type 7 LSAs and is FALSE.

HCIP-Datacom-Advanced Routing & Switching Technology V1.0 Training Material.pdf

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