Users Guide

• Disable a port channel.
shutdown
When you disable a port channel, all interfaces within the port channel are operationally down also.
Load Balancing Through Port Channels
The system uses hash algorithms for distributing traffic evenly over channel members in a port channel (LAG).
The hash algorithm distributes traffic among electronic commerce messaging protocol (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.
The system 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.
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}
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:
• 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.
Interfaces 435