Comprehensive and Detailed Step-by-Step Explanation:
1. Understanding the AS-Path Filter:
* The as-path-filter command is used in BGP to filter routes based on the AS_PATH attribute.
* In this configuration:
* The filter si is defined with the regular expression _65500$.
* The _65500$ expression specifies that the AS_PATH must end with 65500, meaning that the route's last hop must have passed through AS 65500.
2. Option Analysis:
Option A: It accepts only the routes whose AS_Path contains AS 65500.
* Incorrect.
* The _65500$ filter specifically matches routes where AS 65500 is the last AS in the AS_PATH. A route may contain AS 65500 somewhere in the middle of the AS_PATH but will not match this filter unless it is the last AS.
Option B: It accepts only the routes originated from AS 65500.
* Incorrect.
* Routes that originate from AS 65500 have an AS_PATH that starts with 65500. However, the filter
_65500$ only matches routes where AS 65500 is the last AS, not the first AS.
Option C: It accepts only the routes that last pass through AS 65500.
* Correct.
* The _65500$ filter ensures that the AS_PATH ends with 65500. This means that the route must have last passed through AS 65500 before being received by the local BGP router.
Option D: It accepts only the routes forwarded by AS 65500.
* Incorrect.
* While AS 65500 may forward the route, this is not what the filter _65500$ specifically checks for. It only ensures that AS 65500 is the last AS in the AS_PATH.
3. Summary:
* The as-path-filter with _65500$ accepts only the routes where AS 65500 is the last AS in the AS_PATH.

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 default sending interval for BFD (Bidirectional Forwarding Detection) control packets is 100 milliseconds. This interval ensures rapid detection of link faults, providing fast failover and minimizing downtime in network operations .

Comprehensive and Detailed Step-by-Step Explanation:
1. Overview of PBR (Policy-Based Routing):
Policy-Based Routing (PBR) allows you to override traditional routing decisions by defining user-specific policies.
Interface-Based PBR: Applied to packets arriving at a specific interface and affects traffic being forwarded through the device.
Local PBR: Applied to traffic generated by the local router itself (e.g., locally originated packets such as management traffic).
2. Analysis of Each Statement:
Option A: Interface-based PBR takes effect only for forwarded packets.
Correct (True Statement).
Interface-based PBR applies only to packets arriving at a specific interface and being forwarded through the router. It does not affect locally originated traffic.
Option B: Local PBR takes effect only for locally originated packets.
Correct (True Statement).
Local PBR specifically applies to traffic generated by the router itself, such as pings, SNMP requests, or routing protocol updates.
Option C: Interface-based PBR is configured on an interface and takes effect only for incoming packets on the interface.
Correct (True Statement).
Interface-based PBR is applied directly on the interface using commands like policy-based-route. It only affects traffic entering the specified interface.
Option D: Local PBR is configured in the protocol view.
Incorrect (False Statement).
Local PBR is not configured in the protocol view. It is typically configured using the command local-policy in the system view to handle traffic generated by the router.
3. Summary:
answer:D (Local PBR is NOT configured in the protocol view).
Huawei HCIA-Datacom Study Guide, Chapter "Policy-Based Routing."