11-19-2019 09:03 AM
Hello
I would like some information regarding port-channels.
I have heard colleagues in the area of networks say that it is not indicated to build a port-channel with odd number of interfaces, ie the ideal is always to have port-channels with even numbers of interfaces.
Is there any sense in this information? If so, is there any documentation to support such information?
I thank the attention.
Solved! Go to Solution.
11-20-2019 12:56 AM
The Cisco-proprietary hash algorithm computes a value in the range 0 to 7. With this value as a basis, a particular port in the EtherChannel is chosen. The port setup includes a mask which indicates which values the port accepts for transmission. With the maximum number of ports in a single EtherChannel, which is eight ports, each port accepts only one value. If you have four ports in the EtherChannel, each port accepts two values, and so forth. This table lists the ratios of the values that each port accepts, which depends on the number of ports in the EtherChannel:
Number of Ports in the EtherChannel |
Load Balancing |
8 |
1:1:1:1:1:1:1:1 |
7 |
2:1:1:1:1:1:1 |
6 |
2:2:1:1:1:1 |
5 |
2:2:2:1:1 |
4 |
2:2:2:2 |
3 |
3:3:2 |
2 |
4:4 |
Note: This table only lists the number of values, which the hash algorithm calculates, that a particular port accepts. You cannot control the port that a particular flow uses. You can only influence the load balance with a frame distribution method that results in the greatest variety.
Note: The hash algorithm cannot be configured or changed to load balance the traffic among the ports in an EtherChannel.
It is not for the device port number but it is a number of the ports in the port-channel.
11-19-2019 10:52 AM
It does not influence the PortChannel if the number of interfaces is even or odd.
All the manuals and guides I have seen on PortChannel only indicate the maximum number of interfaces per channel.
I attached one of these guides:
Regards
11-20-2019 12:56 AM
The Cisco-proprietary hash algorithm computes a value in the range 0 to 7. With this value as a basis, a particular port in the EtherChannel is chosen. The port setup includes a mask which indicates which values the port accepts for transmission. With the maximum number of ports in a single EtherChannel, which is eight ports, each port accepts only one value. If you have four ports in the EtherChannel, each port accepts two values, and so forth. This table lists the ratios of the values that each port accepts, which depends on the number of ports in the EtherChannel:
Number of Ports in the EtherChannel |
Load Balancing |
8 |
1:1:1:1:1:1:1:1 |
7 |
2:1:1:1:1:1:1 |
6 |
2:2:1:1:1:1 |
5 |
2:2:2:1:1 |
4 |
2:2:2:2 |
3 |
3:3:2 |
2 |
4:4 |
Note: This table only lists the number of values, which the hash algorithm calculates, that a particular port accepts. You cannot control the port that a particular flow uses. You can only influence the load balance with a frame distribution method that results in the greatest variety.
Note: The hash algorithm cannot be configured or changed to load balance the traffic among the ports in an EtherChannel.
It is not for the device port number but it is a number of the ports in the port-channel.
11-21-2019 04:05 PM
Excellent information. Thank you!
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