Dell S6000–ON Configuration Manual page 396

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The nh-ecmp option allows you to change the hash value for recursive ECMP routes independently of

non-recursive ECMP routes. This option provides for better traffic distribution over available equal cost

links that involve a recursive next hop lookup.

To change to another algorithm, use the second command.

Change the default (0) to another algorithm and apply it to ECMP, LAG hashing, or a particular line

CONFIGURATION mode

hash-algorithm {algorithm-number | {ecmp {crc16 | crc16cc | crc32MSB |

crc32LSB | crc-upper | dest-ip | lsb | xor1 | xor2 | xor4 | xor8 | xor16}

[number] hg {crc16 | crc16cc | crc32MSB | crc32LSB | xor1 | xor2 | xor4 |

xor8 | xor16} stack-unit stack-unit-number | port-set port-pipe | hg-seed

seed-value stack-unit | lag {checksum | crc | xor} [number] nh-ecmp {checksum

| crc | xor}[number] stack—unit number ip-sa-mask value ip-da-mask value |

seed seed-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

hash-algorithm [ecmp{crc16|crc16cc|crc32LSB|crc32MSB|crc-upper|dest-ip|lsb|

xor1|xor2|xor4|xor8|xor16}]

Example of the hash-algorithm Command

Dell(conf)#hash-algorithm ecmp xor 26 lag crc 26 nh-ecmp checksum 26

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.

lsb — 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

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