set multicast-hash-mode
Function
The set multicast-hash-mode command specifies a hash algorithm for multicast forwarding.
The undo multicast-hash-mode command restores the default hash algorithm for multicast forwarding.
By default, the crc-32-lower algorithm is used.
Only the S5720-EI, S6720-EI, and S6720S-EI support this command.
Format
set multicast-hash-mode { crc-32-upper | crc-32-lower | lsb | crc-16-upper | crc-16-lower }
undo set multicast-hash-mode { crc-32-upper | crc-32-lower | lsb | crc-16-upper | crc-16-lower }
Parameters
| Parameter | Description |
|---|---|
| crc-32-upper | Indicates the hash algorithm based on high-order bits of CRC32. |
| crc-32-lower | Indicates the hash algorithm based on low-order bits of CRC32. |
| lsb | Indicates the hash algorithm based on the least significant bit of multicast IP addresses. |
| crc-16-upper | Indicates the hash algorithm based on high-order bits of CRC16. |
| crc-16-lower | Indicates the hash algorithm based on low-order bits of CRC16. |
Usage Guidelines
Usage Scenario
To improve multicast forwarding performance, the switch uses a hash algorithm to learn multicast addresses. If multiple addresses match a key value, a hash conflict occurs. A large number of hash conflicts will cause failures to learn some multicast addresses. When such a problem occurs, use an appropriate hash algorithm to reduce hash conflicts.
Precautions
An appropriate hash algorithm can reduce but not eliminate hash conflicts.
MAC addresses are distributed on a network randomly, so the system cannot determine the best hash algorithm. The default hash algorithm is the best algorithm in most cases, so changing the hash algorithm is not recommended.
After changing the hash algorithm, restart the switch for the configuration to take effect.