3com S7906E Installation Instruction

 

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Besides, if the IRF ports are not connected correctly (that is, IRF-port1 of a device is connected to 

IRF-port2 of another device), the slaves will reboot and try to join the IRF again. 

Therefore, to make the IRF system operate normally, you need to make sure that the link state is normal 

and connect the IRF ports of two devices correctly before configuring an IRF; after the establishment of 

the IRF, configure necessary anti-attack policies to ensure device safety. 

IRF link failures may cause an integral IRF system to split in to two or more IRFs operating with the 

same global configuration. Because these IRFs look the same to other devices in the network, network 

failure probably occurs. To offset the risk, the multi-active detection (MAD) mechanism is introduced. 

The MAD mechanism detects the presence of multiple identical IRFs split from an IRF system and 

handles the problem to make the network operate normally. The MAD mechanism provides the 

following functions: 

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Detection: Enabled in an IRF system, the MAD mechanism periodically detects the IRF system for 

multiple active IRFs with the same global configuration. This is done with the Link Aggregation 

Control Protocol (LACP), and the Bidirectional Forwarding Detection (BFD) protocol. 

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Collision handling: If multiple identical active IRFs are detected, the MAD mechanism keeps only 

the one with the lowest master ID (the active ID) to operate normally. The state of all the other IRFs 

will be set to recovery and all the ports in them will be shut down except for the IRF ports and ports 

manually specified not to shut down. 

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Failure recovery: The MAD mechanism prompts the user for multi-active collision, and the device 

then tries to repair the failed IRF links automatically. If the reparation fails, you need to repair the 

failed links manually. After the links are repaired successfully, the split IRF will merge again, and 

the IRF in the recovery state will restore to the active state, all disabled ports come up to forward 

traffic. 

 

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For information about LACP, refer to Link Aggregation Configuration in the Access Volume; for 

information about BFD, refer to BFD Configuration in the High Availability Volume. 

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After an IRF split, the system disables all service ports on the member devices from the loser side 

(that is equal to executing the shutdown command on these ports). However, some ports are not 

disabled and are called reserved ports. By default, only the physical IRF ports are reserved ports. 

To set other ports (such as the port for telnetting) to reserved ports, you need to configure them 

through command lines. 

 

Before configuring an IRF, you need to define the roles and functions of all the members for better 

planning. Because the configuration of some parameters takes effect after device reboot, to make the 

devices for an IRF, you are recommended to first configure parameters and then connect devices 

physically. After a device is added into an IRF, you can only perform service configurations on the