Configuring MAD
Guidelines
You are advised to configure MAD to minimize the impact of a stack split on services.
Configure MAD in direct mode when member switches in a stack have idle ports. Use ordinary cables to connect these ports and use the ports for MAD only.
Configure MAD in relay mode when stack Eth-Trunk is configured in a stack. In relay mode, MAD relay detection is configured on Eth-Trunk ports of the stack, and the MAD relay function is enabled on a relay agent. In contrast with the direct mode, the relay mode does not occupy additional ports.
The relay mode can be implemented in two ways: configuring a single switch as the MAD relay agent or configuring two stack systems as MAD relay agents for each other.
MAD in direct mode can only be configured on Layer 2 Ethernet ports in Up state.
You can configure a maximum of eight direct detection links for each member switch and configure the relay mode on a maximum of four Eth-Trunks in a stack to improve detection reliability. Ensure that one direct detection link on each member switch and one Eth-Trunk in each stack works normally when multiple master switches coexist.
MAD is a Huawei proprietary protocol, and Huawei S series switches support the MAD relay function.
- When configuring MAD in relay mode, ensure that member switches in a stack use different MAC addresses. If they use the same MAC address, the proxy device cannot forward MAD packets.
Procedure
- Configure MAD in direct or relay mode.
- Configure MAD in direct mode.
- Run the system-view command to enter the system view.
- Run the interface interface-type interface-number command to enter the interface view.
- Run the mad detect mode direct command to configure MAD in direct mode.
- MAD packets are bridge protocol data units (BPDUs). If MAD is performed through dedicated direct links between member switches and an intermediate device, configure port-based Layer 2 protocol tunneling on the intermediate device. For details, see Configuring Interface-based Layer 2 Protocol Tunneling in "Layer 2 Protocol Transparent Transmission Configuration" in the S2720, S5700, and S6700 V200R019C10 Configuration Guide - Ethernet Switching.
After MAD in direct mode is configured on an interface, the STP status of the interface becomes Discarding, affecting the transmission of data packets and some protocol packets. Therefore, do not configure other services on this interface.
- Configure MAD in relay mode.
- Switch functioning as the relay agent
- In the stack
- Run the system-view command to enter the system view.
- Run the interface eth-trunk trunk-id command to enter the Eth-Trunk interface view.
- Run the mad detect mode relay command to configure MAD in relay mode on the Eth-Trunk.
- On the specified relay agent
- Run the system-view command to enter the system view.
- Run the interface eth-trunk trunk-id command to enter the Eth-Trunk interface view.
- Run the mad relay command to enable the relay function on the Eth-Trunk.
- In the stack
Two stack systems functioning as the relay agent of each other
In each stack
- Run the system-view command to enter the system view.
- Run the mad domain domain-id command to specify the MAD domain ID for a stack.
By default, the MAD domain ID of a stack is 0.
Two stack systems can function as the relay agent of each other to implement MAD. The two stack systems must be configured with different MAD domain IDs.
- Run the interface eth-trunk trunk-id command to enter the Eth-Trunk interface view.
- Run the mad relay command to enable the relay function on the Eth-Trunk.
- Run the mad detect mode relay command to configure MAD in relay mode on the Eth-Trunk.
- Switch functioning as the relay agent
- Configure MAD in direct mode.
- Run the quit command to return to the system view.
- (Optional) Run the mad exclude interface { interface-type interface-number1 [ to interface-type interface-number2 ] } &<1-10> command to configure specified ports in a stack as reserved ports.
When MAD detects a stack split, multiple stacks compete with each other. You must shut down all service ports on member switches that fail the competition, to avoid MAC address or IP address conflict. If some ports only transparently transmit packets, they do not affect network operations when a stack splits. You can configure these ports as reserved ports to ensure normal packet transmission on them. MAD does not shut down service transmission on these ports when it detects a stack split.
By default, only stack member ports of a stack are reserved ports, and all service ports are non-reserved ports.
After a stack splits, the port used for MAD will also be shut down.
- (Optional) Run the mad restore command to restore shutdown ports to the Up state.
When MAD detects a stack split, multiple stacks compete with each other. The stack that wins the competition remains in the Detect state (normal working state) and the stacks that fail the competition enter the Recovery state (disabled state). In the Recovery state, all the service ports except reserved ports on member switches are shut down, so the stacks do not forward service packets. You can restore shutdown ports to the Up state so that the stacks in Recovery state can work again. For example, if the stack in Detect state fails or is removed from the network before the stack fault is rectified, restore the shutdown ports in a stack in the Recovery state to the Up state, so that the stack in the Recovery state can take over services from the previous active stack. This minimizes the impact of a stack fault on services.
Do not run this command when the stack in the Detect state is working normally. Otherwise, there will be multiple master switches on the network after the stack in the Recovery state is enabled.
If the stack in the Detect state is merged with the stack in the Recovery state, the new stack remains in Recovery state. You need to run the mad restore command to restore shutdown ports to the Up state.