Dell Force10 TeraScale C Series, Reference Manual

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476 | Equal Cost Multi-Path
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hash-algorithm ecmp
c s
Change the hash algorithm used to distribute traffic flows across an ECMP (equal-cost multipath
routing) group.
Syntax hash-algorithm ecmp
{
crc-upper
} | {
dest-ip
} | {
lsb
}
To return to the default hash algorithm, use the
no hash-algorithm ecmp
command.
Parameters
Defaults crc-lower, dest-ip enabled
Command Modes CONFIGURATION
Command
History
Usage
Information
The hash value calculated with the hash-algorithm command is unique to the entire chassis. The
default ECMP hash configuration is
crc-lower
. This takes the lower 32 bits of the hash key to compute
the egress port and is the “fall-back” configuration if the user hasn’t configured anything else.
The different hash algorithms are based on the number of ECMP group members and packet values.
The default hash algorithm yields the most balanced results in various test scenarios, but if the default
algorithm does not provide satisfactory distribution of traffic, then use this command to designate
another algorithm.
When a member leaves or is added to the ECMP group, the hash algorithm is recalculated to balance
traffic across the members.
Related
Commands
hash-algorithm seed
e
Select the seed value for the ECMP, LAG, and NH hashing algorithm.
Syntax hash-algorithm seed value [ linecard slot ] [ port-set number ]
Parameters
Defaults
None
crc-upper
Uses the upper 32 bits of the key for the hash computation
Default:
crc-lower
dest-ip
Uses the destination IP for ECMP hashing
Default:
enabled
lsb
Returns the LSB of the key as the hash
Default:
crc-lower
Version 7.6.1.0 Introduced on S-Series
Version 7.5.1.0 Introduced on C-Series
load-balance (C-Series and
S-Series)
seed value Enter the keyword followed by the seed value.
Range: 0 - 4095
linecard slot Enter the keyword followed by the line card slot number.
port-set number Enter the keyword followed by the line card port-pipe number.