Dell Force10 C150 Configuration Manual page 439

Hash algorithm
load-balance
The
If even distribution is not obtained with the load-balance command, the
used to select the hash scheme for LAG, ECMP and NH-ECMP. The 12 bit Lag Hash can be rotated or
shifted till the desired hash is achieved.
nh-ecmp
The 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.
For the E-Series TeraScale and ExaScale, you can select one of 47 possible hash algorithms (16 on
EtherScale).
Command Syntax
hash-algorithm {algorithm-number} |
{ ecmp { checksum|crc|xor }
[number]} lag
{checksum|crc|xor][number]} nh-ec
mp {[checksum|crc|xor] [number]}}|
{ linecard number ip-sa-mask value
ip-da-mask value}
Note: E-Series systems require the
E-Series TeraScale
e
ExaScale
x
microcode.
Figure 20-19 shows a sample configuration for the
Figure 20-19. Command example:
FTOS(conf)#FTOS(conf)#hash-algorithm
FTOS(conf)#
On C-Series and S-Series, the
defaults from the E-Series. The default ECMP hash configuration is
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
command discussed above selects the hash criteria applied to port channels.
Command Mode
CONFIGURATION
lag-hash-align
e
includes this microcode as an option with the Default cam profile. E-Series
t
systems require that a CAM profile be created and specifically include
hash-algorithm
ecmp xor 26 lag crc 26 nh-ecmp checksum 26
hash-algorithm
Purpose
Change the default (0) to another algorithm and apply
it to ECMP, LAG hashing, or a particular line card.
Note: To achieve the functionality of hash-align
on the ExaScale platform, do not use CRC as an
hash-algorithm method. For ExaScale systems,
set the default hash-algorithm method to ensure
CRC is not used for LAG. For example,
hash-algorithm ecmp xor lag checksum nh-ecmp
checksum
For details on the algorithm choices, see the command
details in the IP Routing chapter of the
Command Reference.
microcode be configured in the in the CAM profile.
hash-algorithm
command.
command is specific to ECMP groups and has different
crc-lower
hash-algorithm
command can be
FTOS
lag-hash-align
. This takes the lower 32 bits
Interfaces | 439