Want to know about ACE module in 6509 : load-balancing concept

Question

Hi,
I am quite new in this field , where i need to configure and understand the concept of load-balancing through ACE.
In my existing network set-up , i have some application servers as well as some other servers where i am looking for load-balancing.
I have gone through some of the site and cisco site as well and i came across ACE module which can be installed in 6509 switch.
I have 6509 switch as well but before going for installing the ACE module I am keen to understand below things:
1) what is difference between CSM or any other product load-balancer and ACE module :
Gone through site as well , but not getting proper answer or comparison.
1) I have some of the server configured with clustering and getting one virtual IP, In this case , will ACE work ?
2) If suppose i go for configuring different IP address with all server IP :
How do i achieve it ?
3) what is Virtual IP concept in ACE because i do not have and other ACE module then why do i need virtual IP ?
4) will the load-balancing happens based on destination based or session based ?
Please share the knowledge. It would be great help for me to go ahead with ACE and configure it and understand all the application ?

Answer 1

Hello,
1) what is  difference between CSM or any other product load-balancer and ACE  module :
There are several differences but to say simply, you get higher performance and more features with ACE module/appliance comparing others.
One big difference is that with ACE seriese, you can configure multiple contexts on one box (virtual load-balancers on one box) that makes us possible to provide a virtual load-balancer to a customer. In that way, the customer can access and makes changes on only the virtual box. You can split management domain for each customers. Also using contexts, you can assign certain resources available on the hardware for each contexts according to their service contract.
ACE serise has specific hardware chip for supporting SSL termination but some others do not.
For instance, you need a CSM-S, or a CSM and a SSL module to terminate SSL.
The other thing I should mention is that our most recent product is ACE serise that means it has longer product roadmap.
Let me try clarifying your other questions.
3)  what is Virtual IP concept in ACE because i do not have and other ACE  module then why do i need virtual IP ?
4) will the load-balancing happens  based on destination based or session based ?
I think I'd better to put 3) and 4) first.
Virtual ip  address (VIP) is the address to which client accesses.
VIP is tied with a  serverfarm or serverfarms, in a serverfarm one or multiple rservers can  be configured.
"serverfarm" is a group of "rservers".
"rserver" means  real-server that has an ip address and processes transactions.
When a client  accesses to the VIP, ACE picks up a rserver according to algorithm.
If you configure a  VIP that is tied with a serverfarm where only one rsever is  configured, client accesses to the virtual ip address are
all forwarded to  the rserver.
If you configure a  VIP that is tied with a serverfarm where multiple rsevers are  configured,  client accesses to the virtual ip address are
balanced among  those rservers.
If you configure  multiple VIPs, client accesses to those VIPs are forwareded to  corresponding rservers according to configuration.
1)  I have some of the server configured with clustering and getting one  virtual IP, In this case , will ACE work ?
ACE load-balances connections to configured rservers.
If the clustered servers are sharing one virtual ip address and you configure the virtual ip address as a rserver, all connections are
sent to the virtual ip address. That is not "load-balancing" on ACE... You need multiple rservers to which ACE load-balances connections.
2) If suppose i go for  configuring different IP address with all server IP :
How do i  achieve it ?
You can configure those ip addresses as rserver ip address.
Multiple rservers are tied into a group, "serverfarm".
I'm not certain about your culstered servers but I guess you can configure each ip addresses in the culster as rservers.
Then put those rservers in a serverfarm.Client accesses to a virtual ip address configured on ACE for the serverfarm.
This way connections are load-balanced among those rservers depending on load-balancing algorithm you choose.
Above is just an overveiw. ACE gives you granular control not mentioned above.
I can provide more specific information if you tell me details of what you are trying to archive with ACE.
Regards,
Kimihito.