H12-821_V1.0 Exam Dumps - Huawei HCIP-Datacom Questions and Answers

 GRE Characteristics

GRE does not inherently support encryption or authentication. It is a tunneling protocol for encapsulating packets, and data security features must be implemented using other protocols such as IPsec.

Other correct attributes of GRE include:

B. Supports multicast transmission.

C. Acts as a Layer 3 VPN encapsulation technology.

D. Can work with VPN protocols like IPsec for better security.

 HCIP-Datacom-Core Reference

GRE features and limitations are discussed in VPN encapsulation technology chapters​​.

The LS age field in OSPF LSAs (Link State Advertisements) is measured in seconds and increments over time in the Link State Database (LSDB). If the LS age reaches the LSRefreshTime (30 minutes), the router that originated the LSA must regenerate it to keep the LSA valid in the network. Options C and B are incorrect since LS age does not decrease, and only the originator regenerates LSAs ​.

High-availability Stateful Backup (HSB) ensures synchronization between active and standby devices. If the HSB channel fails to establish, the following causes are possible:

TCP channel not established : The HSB channel relies on a TCP connection. If the TCP session cannot be established, the backup process cannot start.

Mismatched retransmission settings : If the retransmission count and interval for HSB service packets are inconsistent between the two devices, the synchronization process fails.

Incorrect source and destination configurations : If the source IP address and port number on one device do not match the destination IP address and port number on the other, the channel cannot be established.

Option C is incorrect because the priority of the two ACs affects active/standby roles but does not directly impact HSB channel establishment ​.

Inter-area route calculation in OSPF involves Summary LSAs (Type 3) for summarizing routes across areas and ASBR Summary LSAs (Type 4) for locating ASBRs. While Router LSAs and Network LSAs describe the internal structure of an area, they do not directly participate in inter-area route calculation. Thus, the statement that only Router, Network, and Summary LSAs are involved is false ​.

When configuring VRRP, the virtual router priority and virtual IP address are mandatory because they define the VRRP instance and its role within the group. Preemption mode and preemption delay are optional configurations that influence how routers take over the master role when priorities change. These are not mandatory for the VRRP protocol to function ​.

Option A is false . When advertising a route to an IBGP peer, the BGP speaker does not modify the AS_Path. It simply advertises the route as-is , preserving the AS_Path learned from EBGP.

Clarification of the options:

B is correct: When a route is sent to an EBGP peer, the local AS is prepended to the AS_Path.

C is correct: The AS_Path begins with the local AS when a new route is advertised to an EBGP neighbor.

D is correct: IBGP does not modify AS_Path when passing routes within the same AS.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“BGP speakers prepend their AS number to the AS_Path only when advertising to EBGP peers. IBGP peers do not alter the AS_Path.”

(Chapter: BGP Path Attributes – Section: AS_Path)