show port-channel traffic

katerina.dardoufa · ‎10-09-2014

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

Harish Balakrishnan · ‎10-09-2014

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.

vishal vyas · ‎10-09-2014

Please see this link:

https://supportforums.cisco.com/blog/150511/how-do-etherchannel-hash-algorithm-works-and-load-distribution-happen

katerina.dardoufa · ‎10-20-2014

Thanks for the link and the great information.

I will try to change the algorithm and see what happens.

Thanks

InayathUlla Sharieff · ‎10-09-2014

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

tachavez · ‎05-29-2019

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.