10-09-2014 06:04 AM - edited 03-07-2019 09:03 PM
Hello all,
I have 3 port-channels configured for LACP on our Nexus1000V. The uplinks end on a 2960S stack switch, where LACP is also configured.
By running "show port-channel traffic" I get the following.
sh port-channel traffic
ChanId Port Rx-Ucst Tx-Ucst Rx-Mcst Tx-Mcst Rx-Bcst Tx-Bcst
------ --------- ------- ------- ------- ------- ------- -------
1 Eth5/3 37.83% 0.00% 48.05% 50.32% 16.97% 27.52%
1 Eth5/4 62.16% 99.99% 51.94% 49.67% 83.02% 72.47%
------ --------- ------- ------- ------- ------- ------- -------
2 Eth3/2 19.66% 85.56% 47.82% 58.93% 14.60% 94.64%
2 Eth3/4 80.33% 14.43% 52.17% 41.06% 85.39% 5.35%
------ --------- ------- ------- ------- ------- ------- -------
4 Eth4/2 3.54% 97.92% 39.71% 51.32% 27.00% 59.91%
4 Eth4/4 96.45% 2.07% 60.28% 48.67% 72.99% 40.08%
My question is, why isn't traffic evenly distributed between ethernet interfaces, belonging to the same port-channel.
Load balancing is configured as follows:
sh port-channel load-balance
Port Channel Load-Balancing Configuration:
System: source-mac
Port Channel Load-Balancing Addresses Used Per-Protocol:
Non-IP: source-mac
IP: source-mac
Thank you in advance,
Katerina
10-09-2014 07:25 AM
Hello Katerina
This is pretty much expected result when you have one server send out more traffic. If you could change the load sharing method to src-dst-ip or src-dst-mac ( based on your traffic flow) you should be able to see better results
Hope this helps
Harish.
10-09-2014 07:42 AM
Please see this link:
https://supportforums.cisco.com/blog/150511/how-do-etherchannel-hash-algorithm-works-and-load-distribution-happen
10-20-2014 06:33 AM
Thanks for the link and the great information.
I will try to change the algorithm and see what happens.
Thanks
10-09-2014 07:44 AM
This is expected result.
AS said if you want to see some different or close match between the interfaces you need to try changing the load balancng algorithm on the device.
HTH
05-29-2019 02:53 PM
Because how the load balancing hash works on Cisco devices.
Ports 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
From this we should expect to have even load balancing traffic on interfaces? Not necessarily:
On this scenario it depends on both, the individual flows traversing the port channel and the load balancing method. PO1 is sending 60% of traffic to (1) destination mac address on E5/4 due to the source-mac load balancing method whereas it is receiving at least (2) even flows of traffic load balancing it among E5/4 and E5/3. For multicast traffic it is sending all of the traffic to (1) destination mac, having 100% of utilization on E5/4.
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