cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
557
Views
0
Helpful
5
Replies
Highlighted
Beginner

ACE - Round Robin appears to be doing slow-start

Hi All,

We have a pair of ACE4710s and I am seeing some odd behaviour when adding a new server to a server farm. What appears to be happening is that when a new server is added to a farm set with Round Robin as it's predictor, it appears to be operating a slow-start type service to the new server. What I mean is that the new server gets less connections served to it than the existing servers in the farm.

When I run a show server farm command after clearing the stats the total connections grow incremental as I would expect, the current connections on the new server slowly grows. However, when inspecting the actual hits on the real servers both new to the farm and the servers that were in the farm originally, It shows that the original servers are getting hit more frequently than the new server. I would have expected the all the servers to be hit fairly spread across the farm.

So it appears that the load balancer is operating a slow-start on new servers being added in a Round Robin farm.

If I place all servers both new and existing in the farm out of service and then bring them all back in togather, then everything is fine and the servers show that the load is being distributed evenenly across them.

Any ideas?

Thanks for your help

Ryan

5 REPLIES 5
Highlighted
Cisco Employee

ACE - Round Robin appears to be doing slow-start

Hi Ryan,

In round-robin the connections should be balanced evenly across all servers or according to weight. If there is no weight configured, new connections should be evenly balanced across all servers including the one which you have just put in "inservice". The slow-start is for least connections predictor.

Regards,

Kanwal

Highlighted
Beginner

ACE - Round Robin appears to be doing slow-start

Hi Kanwal,

Thanks for the reply. All the servers are configureed with the default weight of 8. I realise that the slow-start option is only available for the least connections predictor. What I meant was that even though all the server weights are the same, when a new server is added to the farm, the behaviour I see in that the new server gets less connections than the existing servers is that the load balancer appears to be doing a slow-start on it.

Regards

Ryan

Highlighted
Beginner

ACE - Round Robin appears to be doing slow-start

Ryan,

Are you using sticky for this traffic? If so that would explain why the newly added server is getting less connections than the ones that are already inservice.

Regards

Jim

Highlighted
Enthusiast

ACE - Round Robin appears to be doing slow-start

Hi Ryan,

can you send the configuration you are using for this?  It looks that stickiness is causing this behavior

---------------------
Cesar R
ANS Team

--------------------- Cesar R ANS Team
Highlighted
Cisco Employee

ACE - Round Robin appears to be doing slow-start

Hi Ryan,

Well that could be due to stickyness as told by other gentlemen but one thing is for sure that round-robin doesn't care about the connections and sends the new connection to next server in the list so server slow-starting is ruled out in round robin.

Regards,

Kanwal