Layer 2 forwarding policy feature of the access network

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Layer 2 forwarding policies include VLAN+MAC address, S-VLAN+C-VLAN, VLAN+MAC address+CoS, and S-VLAN+C-VLAN+CoS.

Other related questions:
How to check whether forwarding is looped on a Layer 2 network
The following events indicate that forwarding is looped on a Layer 2 network: Massive congestion and full-bandwidth storm. Run the display interface ethernet brief | include up command to check whether the incoming and outgoing traffic of a port reaches the maximum. Massive MAC address flapping is found during MAC flapping detection. Run the display trap logbuffer command to check whether MAC address flapping alarms are generated.

Query MAC address flapping records on S series switch
When loops occur on S series switches (except S1700), MAC address flapping often occurs. You can check whether MAC address flapping occurs on a switch to determine whether a loop occurs on the switch. Methods to check MAC address flapping vary depending on the system version. 1. In versions earlier than V200R001 on S series switches: Run the display trapbuffer command. If the command output displays MAC move detected, MAC address flapping occurred on the switch. 2. E series switches and S series switches running V200R001 and later versions: - Run the display trapbuffer command. If the command output displays MAC move detected, MAC address flapping occurred on the switch. - Run the display mac-address flapping record command. If information is displayed, MAC address flapping occurred on the switch.

Are packets in a bridge group forwarded at Layer 2 or Layer 3
Packets in a bridge group are forwarded at Layer 2. Only interfaces supporting Layer 3 functions can be added to a bridge. Data in a bridge, however, is forwarded at Layer 2.

Whether the firewall supports Layer 2 or Layer 3 forwarding
The USG2000&5000&6000 support implementing the Layer 2 forwarding function in transparent mode. When the firewall implements route-based forwarding, the Layer 3 forwarding function is used.

Default Layer 2 multicast forwarding mode on an S series switch
For S series switches excluding the S1700, after Layer 2 multicast is enabled, the S1720, S2710SI, S2700SI, S2700EI, S2720EI, S2750EI, S5700LI, and S5700S-LI (S5700S-28X-LI-AC and S5700S-52X-LI-AC) forward multicast data based on MAC addresses, and other models forward multicast data based on IP addresses by default.

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