After Layer 3 roaming, the STA's traffic is forwarded from the Foreign AP (FAP) to the Foreign AC (FAC), and then to the Home AC (HAC) before reaching the upper-layer network. This ensures that the STA remains on the same subnet without breaking existing sessions .

In Layer 3 roaming scenarios, STAs (stations) remain on different subnets before and after roaming. To ensure that user traffic reaches the original subnet, it must be tunneled back over a CAPWAP tunnel. This technique prevents disruptions in communication and enables seamless roaming. Huawei's Layer 3 roaming design guidelines emphasize the use of CAPWAP tunnels for user traffic forwarding .

* Understanding DHCPv6:
* DHCPv6 (Dynamic Host Configuration Protocol for IPv6) is used to assign configuration parameters to IPv6 clients.
* It supports both stateful and stateless modes:
* Stateful: Assigns IPv6 addresses and other configuration parameters.
* Stateless: Assigns only configuration parameters (e.g., DNS server) without providing IPv6 addresses.

Explanation:
Network Types and Corresponding Link Layer Protocols
* Broadcast: Ethernet
* Point-to-Point (P2P): PPP, HDLC
* Point-to-Multipoint (P2MP): PPP
* Non-Broadcast Multi-Access (NBMA): Frame Relay
OSPF Network Types:OSPF classifies networks based on link layer protocols into the following types:
* Broadcast: This type assumes that all routers on the network can communicate directly with one another using multicast or broadcast frames. Ethernet networks are typical examples.
* Point-to-Point (P2P): This type is used for links that connect two routers directly. Common protocols include PPP (Point-to-Point Protocol) and HDLC.
* Point-to-Multipoint (P2MP): This type simulates multiple point-to-point connections over a single physical network, often used in WAN scenarios where PPP is employed.
* Non-Broadcast Multi-Access (NBMA): These networks connect multiple devices but lack native broadcast capability, such as Frame Relay.

* Mandatory BGP Attributes
* Next_Hop: Specifies the next hop to reach the destination.
* AS_Path: Lists the autonomous systems traversed, crucial for loop prevention and route selection.
* Optional Attributes
* MED (Multi-Exit Discriminator) and Local_Preference are optional attributes that aid in route preference but are not mandatory.
* HCIP-Datacom-Core Reference
* BGP attribute behavior and classifications are detailed in BGP path selection principles.