Interfaces |
439
Hash algorithm
The
load-balance
command discussed above selects the hash criteria applied to port channels.
If even distribution is not obtained with the load-balance command, the
hash-algorithm
command can be
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.
The
nh-ecmp
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).
Figure 20-19
shows a sample configuration for the
hash-algorithm
command.
Figure 20-19. Command example:
hash-algorithm
On C-Series and S-Series, the
hash-algorithm
command is specific to ECMP groups and has different
defaults from the E-Series. The default ECMP hash configuration is
crc-lower
. This 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
Command Syntax
Command Mode
Purpose
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
}
CONFIGURATION
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
FTOS
Command Reference
.
Note:
E-Series systems require the
lag-hash-align
microcode be configured in the in the CAM profile.
E-Series TeraScale
e
t
includes this microcode as an option with the Default cam profile. E-Series
ExaScale
e
x
systems require that a CAM profile be created and specifically include
lag-hash-align
microcode.
FTOS(conf)#FTOS(conf)#
hash-algorithm
ecmp xor 26 lag crc 26 nh-ecmp checksum 26
FTOS(conf)#
Summary of Contents for Force10 E300
Page 1: ...FTOS Configuration Guide FTOS 8 4 2 7 E Series TeraScale C Series S Series S50 S25 ...
Page 32: ...32 w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 132: ...132 802 1X w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 310: ...310 Configuration Replace and Rollback w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 330: ...330 Dynamic Host Configuration Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 402: ...402 High Availability w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 462: ...462 Interfaces w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 482: ...482 IPv4 Addressing w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 506: ...506 IPv6 Addressing w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 582: ...582 Layer 2 w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 642: ...642 Multicast Source Discovery Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 662: ...662 Multiple Spanning Tree Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 690: ...690 Object Tracking w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 754: ...754 PIM Dense Mode w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 784: ...784 PIM Source Specific Mode w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 800: ...800 Power over Ethernet w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 876: ...876 Quality of Service w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 892: ...892 Routing Information Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1006: ...1006 Simple Network Management Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1018: ...1018 SONET SDH w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1048: ...1048 Broadcast Storm Control w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1096: ...1096 Uplink Failure Detection UFD w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1098: ...1098 Upgrade Procedures w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1196: ...1196 C Series Debugging and Diagnostics w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1252: ...1252 Standards Compliance w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1262: ...1262 Index w w w d e l l c o m s u p p o r t d e l l c o m ...