acrhitecture of network load balancing solution

[george]

i'm working on a setup that will transition our existing data center setup to a network load balancing solution. i'm far from understanding what components to use and how to approach the problem so any help would be very welcome. here is what we currently have:

1. 3 web servers (serverA, serverB, serverC)

2. 1 sql server

3. 2 layer two unmanaged switches

4. 1 cisco firewall

each one of the web servers runs a dedicated web app. what i would like is to replace serverA with a NLB cluster of 3 servers and replace serverB with another NLB cluster of 3 servers. serverC is not getting that much usage and it can stay as is.

i have looked at possible solution with Windows Server 2008 NLB and it seems that the best way to do it would be using multicasting which requires upgrading out switches. at the same time if would much more prefer to use hardware load balancing than Windows Server. so i looked at Cisco ACE 4710 appliance. however it seems that some of the cisco switches will also do load balancing. now i'm completely confused whether to upgrade the switches and use them for load balancing or use the ACE appliance. i would appreciate any advices and suggestions. also, any recommendations on breaking up the network using VLANs - if it is necessary with either one of the solutions or if there is some benefit. i guess i'm looking for a "best practices" solution...

any links or documents would be very welcomed.

thanks.

[huangedmc]

Docs for the ACE module can be found here:

http://www.cisco.com/en/US/products/ps6906/tsd_products_support_model_home.html

I don't have experience w/ Microsoft NLB, but I personally think Cisco's hardware LB's should perform much better.

You can either have a 6500 w/ ACE module, or an ACE4700 appliance.

The choice depends on your environment.

You need to have a minimum of three VLAN's - Internet, DMZ (web servers), and internal (SQL).

Beyond these points I'm not sure what else I can tell you...you may need to get an external consultant on this one.

[george]

thanks for your response. i think i'm going with ace 4710. now, as far as vlans go why would i need internet, dmz and internal vlan in my datacenter? i understand that this may be a bit off topic but what is really bugging me is this: with the current setup all of the web servers have 2 nics - one with public IP and one with private IP. same goes with the sql server. on web servers nics with private IPs are used for communicating with the database server. they could very well communicate using nics with public IPs but the person that set this up (i recently inherited it) was convincing me that with the existing setup "public" nics are not burdened with communication between web servers and database server. is this "correct" way of doing it?