When routes are imported into BGP using the import-route command, the origin attribute is set to incomplete by default. This indicates that the route ' s origin is not known or is from an external source, as opposed to being explicitly learned through an IGP ( IGP ) or EGP ( EGP ) protocol ​.

 Additional Port Roles in MSTP

Master Port : Indicates the port on the shortest path to the root bridge in a region.

Regional Edge Port : Identifies a port at the boundary of the MST region.

Backup and edge ports exist in RSTP and are not newly introduced by MSTP.

 HCIP-Datacom-Core Reference

MSTP port roles are elaborated in the MSTP configuration sections​​.

A stateful inspection firewall tracks the state of network connections and only matches the initial packet against its rule set. Subsequent packets in the same connection are matched in the state table. Contrary to this, UDP packets can be inspected by correlating them with connection states, and packets in a single connection are always correlated ​.

The filter-policy command in IS-IS is used to control the advertisement and filtering of routing information. However, it does not directly filter LSPs (Link State Packets); instead, it controls route advertisements. The false statement here is that it filters LSPs ​.

Comprehensive and Detailed In-Depth Explanation:

Stub areas do not allow external routes (Type 5 LSAs).

Since ASBRs are responsible for redistributing external routes into OSPF, they cannot exist in a stub area .

If an ASBR were placed in a stub area, it would attempt to inject external routes into the OSPF domain, which contradicts the stub area rules.

To allow external routes, Not-So-Stubby Areas (NSSAs) are used instead, which allow ASBRs and use Type 7 LSAs to carry external routes.

???? Reference: Huawei HCIA-Datacom Study Guide, OSPF Area Types and ASBR Restrictions.

In an OSPF broadcast or NBMA network with at least two routers, one router must act as the DR (Designated Router), and another as the BDR (Backup Designated Router) to ensure efficient communication and reduce the number of adjacencies. This is a requirement for OSPF operation in such network types ​.

A is false – The correct formula is: Skew_Time = (256 - Priority)/256 × Advertisement_Interval.

B is false – By default, the preemption delay is typically 0s , not 1s, meaning a higher-priority backup router can preempt immediately unless configured otherwise.

C is true – The default Advertisement interval in VRRP is 2 seconds .

D is true – The formula Master_Down_Interval = 3 × Advertisement_Interval + Skew_Time is correct.

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

“The VRRP Skew_Time is calculated as (256 - Priority)/256 × Adver_Interval. The Master_Down interval includes this Skew_Time to stagger failover.”

(Chapter: High Availability – Section: VRRP Timer Mechanism)

 Transitive vs. Non-Transitive Attributes

The Community attribute is a transitive optional attribute , meaning that if a router receives a route with this attribute and does not understand its purpose, the router retains and propagates it to other peers.

Other options, such as AS_Path and MED, are well-defined mandatory or optional attributes with specific purposes.

 HCIP-Datacom-Core Reference

The behavior of optional transitive attributes is detailed in the BGP protocol and attribute chapters​​.

The forwarding plane of a switch consists of data forwarding hardware, such as line cards or forwarding engines, and is responsible for tasks like encapsulating/decapsulating packets, providing high-speed data channels, and collecting packet statistics. However, main control boards are part of the control plane, not the forwarding plane. This distinction ensures a separation of data forwarding and control functionalities ​.