API Guide

Load Balancing Through Port Channels
Dell Networking OS uses hash algorithms for distributing traffic evenly over channel members in a port channel (LAG).
The hash algorithm distributes traffic among Equal Cost Multi-path (ECMP) paths and LAG members. The distribution is based on a flow,
except for packet-based hashing. A flow is identified by the hash and is assigned to one link. In packet-based hashing, a single flow can be
distributed on the LAG and uses one link.
Packet based hashing is used to load balance traffic across a port-channel based on the IP Identifier field within the packet. Load
balancing uses source and destination packet information to get the greatest advantage of resources by distributing traffic over multiple
paths when transferring data to a destination.
Dell Networking OS allows you to modify the hashing algorithms used for flows and for fragments. The load-balance and hash-algorithm
commands are available for modifying the distribution algorithms.
NOTE: Hash-based load-balancing on multi-protocol label switching (MPLS) does not work when you enable packet-
based hashing (load-balance ip-selection packet-based).
Changing the Hash Algorithm
The load-balance command selects the hash criteria applied to port channels.
If you do not obtain even distribution with the load-balance command, you can use the hash-algorithm command to select the
hash scheme for LAG, ECMP and NH-ECMP. You can rotate or shift the 12–bit Lag Hash until the desired hash is achieved.
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 card.
CONFIGURATION mode
hash-algorithm {ecmp {crc16 | crc16cc | crc32MSB | crc32LSB | crc–upper | dest-ip | lsb |
xor1 | xor2 | xor4 | xor8 | xor16} | hg {crc16 | crc16cc | crc32MSB | crc32LSB | xor1 |
xor2 | xor4 | xor8 | xor16} | hg-seed seed-value | lag {crc16 | crc16cc | crc32MSB |
crc32LSB | xor1 | xor2 | xor4 | xor8 | xor16} | seed seed-value } [linecard
slot-id [port-
set port-pipe]]
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 to another algorithm.
CONFIGURATION mode
hash-algorithm ecmp {crc-upper} | {dest-ip} | {lsb}
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:
• 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 — always uses the least significant bit of the hash key to compute the egress port.
Bulk Configuration
Bulk configuration allows you to determine if interfaces are present for physical interfaces or configured 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 configuration excludes from configuration any non-existing interfaces from an interface range. A default VLAN may be configured
only if the interface range being configured consists of only VLAN ports.
Interfaces
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