Configuring a MAC Hash Algorithm
Context
A device usually uses a hash algorithm to learn MAC address entries to improve MAC address forwarding performance. When multiple MAC addresses map the same key value, a MAC address hash conflict may occur. When a MAC address hash conflict occurs, the device may fail to learn many MAC addresses and can only broadcast traffic destined for these MAC addresses. The heavy broadcast traffic increases the load on the device. In this case, use an appropriate hash algorithm to mitigate the hash conflict.
- Only the CE12800E that has the FD-X series cards installed supports the configuration of a Hash Algorithm.
MAC addresses are distributed on a network randomly, so the best hash algorithm cannot be determined. Generally, the default hash algorithm is the best one, so do not change the hash algorithm unless you have special requirements.
An appropriate hash algorithm can reduce hash conflicts, but cannot prevent them.
After the hash algorithm is changed, restart the to make the configuration take effect.
Procedure
- Run system-view
The system view is displayed.
- Run mac-address hash-mode { crc16-lower | crc16-upper | crc32-lower | crc32-upper | lsb }
A hash algorithm is configured.
The default hash algorithm is crc32-lower.
- Run commit
The configuration is committed.
Verifying the Configuration
Run the display mac-address hash-mode command to check the running and configured hash algorithms.
Run the display mac-address hash-conflict [ mac-address { vlan vlan-id | bridge-domain bd-id } ] [ slot slot-id ] command to check the MAC address that cannot be added to the chip due to the hash conflict.
