# Cannot distribute traffics evenly by using round robin

**URL:** <https://community.a10networks.com/t/cannot-distribute-traffics-evenly-by-using-round-robin/375>\
**Category:** ADC - Application Delivery\
**Tags:** load-balancing-method, slb-adc\
**Created:** [February 1, 2016, 5:15am UTC](https://community.a10networks.com/t/cannot-distribute-traffics-evenly-by-using-round-robin/375 "2016-02-01T05:15:09Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![escgate](https://avatars.discourse-cdn.com/v4/letter/e/51bf81/32.png) [@escgate](https://community.a10networks.com/u/escgate)\
**Post date:** [February 1, 2016, 5:15am UTC](https://community.a10networks.com/t/cannot-distribute-traffics-evenly-by-using-round-robin/375/1 "2016-02-01T05:15:09Z")

</div>

Hello All,

Customer use the round-robin method without any persist template.  
Total sessions are not load balancing evenly below;  
Surely I checked again after clearing sessions. And the monitor of real servers was normal.  
But sessions still distributed evenly.  
I think this issue is limited to my customer…🙂  
However…I wonder if anyone have this experience.

\*v112\_158\_gr\_80 State: All Up  
r112\_143:14080 20 5947332 52365756 51882310 892  
r112\_144:14080 21 5948479 52238493 51658280 906  
r112\_145:14080 21 5948154 52180299 51569971 946  
r112\_146:14080 23 5948650 52240530 49853274 1194

FrontB-L4-1-Active#sh slb server | be r112\_14  
r112\_143:14080/tcp 22 136903414 936764409 1203320848 1148 Up  
r112\_143: Total 22 136903414 936764409 1203320848 1148 Up  
r112\_144:14080/tcp 17 136903086 933975503 1193917435 1167 Up  
r112\_144: Total 17 136903086 933975503 1193917435 1167 Up  
r112\_145:14080/tcp 21 137015956 934610406 1194983543 948 Up  
r112\_145: Total 21 137015956 934610406 1194983543 948 Up  
r112\_146:14080/tcp 24 137013613 934139889 1184469441 1207 Up  
r112\_146: Total 24 137013613 934139889 1184469441 1207 Up

Thanks,  
CB.

---

<div class="post-metadata">

**Author:** ![dshin](https://avatars.discourse-cdn.com/v4/letter/d/f05b48/32.png) [@dshin](https://community.a10networks.com/u/dshin)\
**Post date:** [February 1, 2016, 9:52pm UTC](https://community.a10networks.com/t/cannot-distribute-traffics-evenly-by-using-round-robin/375/2 "2016-02-01T21:52:02Z")

</div>

What ACOS build have you installed? I would like to replicate on our lab? Also what application? Microsoft, standard IIS…please provide details.

Genard

---

<div class="post-metadata">

**Author:** ![escgate](https://avatars.discourse-cdn.com/v4/letter/e/51bf81/32.png) [@escgate](https://community.a10networks.com/u/escgate)\
**Post date:** [February 3, 2016, 12:03am UTC](https://community.a10networks.com/t/cannot-distribute-traffics-evenly-by-using-round-robin/375/3 "2016-02-03T00:03:22Z")

</div>

Genard,  
Thank you for replying.

First, I think I need testing with some verions and IIS web severs.  
I will update the results.

Thanks,  
CB

---

<div class="post-metadata">

**Author:** ![dshin](https://avatars.discourse-cdn.com/v4/letter/d/f05b48/32.png) [@dshin](https://community.a10networks.com/u/dshin)\
**Post date:** [February 3, 2016, 7:05pm UTC](https://community.a10networks.com/t/cannot-distribute-traffics-evenly-by-using-round-robin/375/4 "2016-02-03T19:05:17Z")

</div>

So for round robin algorithm the CPU is monitored during server selection. If a request landed on a CPU that has a heavy load, the request may have to be redirected to another CPU causing the round robin algorithm to not distribute evenly. The A10 round robin has a proprietary selection algorithm based on CPU load. If you want an evenly distributed selection across servers, I would suggest that you try the “round robin strict”. The “round robin strict” will offer an equal distribution of request across servers with no consideration of CPU threshold.