Administrator Guide

• Change the default (0) to another algorithm and apply it to ECMP, LAG hashing, or a particular line card.
CONFIGURATION mode
hash-algorithm {ecmp {crc16 | crc16cc | crc32MSB | crc32LSB | crc-upper | dest-
ip | flow-based-hashing {crc16|crc16cc|crc32MSB|crc32LSB|xor1|xor2|xor4|xor8|
xor16}|lsb | xor1 | xor2 | xor4 | xor8 | xor16}[[hg {crc16 | crc16cc | crc32MSB
| crc32LSB | xor1 | xor2 | xor4 | xor8 | xor16}]| [lag {crc16 | crc16cc |
crc32MSB | crc32LSB | xor1 | xor2 | xor4 | xor8 | xor16 }][stack-unit|linecard
number | port-set number | [hg—seed seed-value | seedseed-value
For more information about algorithm choices, refer to the command details in the IP Routing chapter of
the Dell Networking OS Command Reference Guide.
• Change the Hash algorithm seed value to get better hash value
Hash seed is used to compute the hash value. By default hash seed is chassis MAC 32 bits. we can also
change the hash seed by the following command.
CONFIGURATION mode
hash-algorithm seed {seed value}
• Change to another algorithm.
CONFIGURATION mode
Example of the hash-algorithm Command
Dell(conf)#hash-algorithm ecmp xor1 lag crc16
Dell(conf)#
The hash-algorithm command is specific to ECMP group. The default ECMP hash configuration is crc-
lower
. This command takes the lower 32 bits of the hash key to compute the egress port. Other options for
ECMP hash-algorithms are:
• crc16 — uses 16 bit CRC16-bisync polynomial
• crc16cc — uses 16 bit CRC16 using CRC16-CCITT polynomial
• crc32LSB — uses LSB 16 bits of computed CRC32
• crc32MSB — uses MSB 16 bits of computed CRC32(default)
• crc-upper — uses the upper 32 bits of the hash key to compute the egress port.
• dest-ip — uses destination IP address as part of the hash key.
• flow-based-hashing — uses flow-based-hashing followed by the algorithm crc16 |crc16cc |
crc32MSB |crc32LSB |xor1 |xor2 |xor4 |xor8 | xor16.
• lsb —always uses the least significant bit of the hash key to compute the egress port.
• xor1 — uses Upper 8 bits of CRC16-BISYNC and lower 8 bits of xor1
• xor2 — Upper 8 bits of CRC16-BISYNC and lower 8 bits of xor2
• xor4 —Upper 8 bits of CRC16-BISYNC and lower 8 bits of xor4
• xor8 — Upper 8 bits of CRC16-BISYNC and lower 8 bits of xor8
• xor16 — uses 16 bit XOR.
Interfaces 426