Concept Guide

For more information about algorithm choices, refer to the command details in the IP Routing chapter of the Dell EMC 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
DellEMC(conf)#hash-algorithm ecmp xor 26 lag crc 26 nh-ecmp checksum 26
DellEMC(conf)#
The hash-algorithm command is specic to ECMP group. The default ECMP hash conguration 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 signicant 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.
Bulk Conguration
Bulk conguration allows you to determine if interfaces are present for physical interfaces or congured for logical interfaces.
Interface Range
An interface range is a set of interfaces to which other commands may be applied and may be created if there is at least one valid interface
within the range.
Bulk conguration excludes from conguration any non-existing interfaces from an interface range. A default VLAN may be congured only
if the interface range being congured consists of only VLAN ports.
The interface range command allows you to create an interface range allowing other commands to be applied to that range of
interfaces.
The interface range prompt oers the interface (with slot and port information) for valid interfaces. The maximum size of an interface
range prompt is 32. If the prompt size exceeds this maximum, it displays (...) at the end of the output.
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Interfaces