Server Load Balancing is an advanced feature supported by Cisco Switches in the 45XX and 65XX Line of Multi-Layer Switches.
The Feature allows a Virtual IP address to be configured on the switch. This Virtual Ip Address or VIP will be used to represent a cluster of servers on a given network.Most persons will never require a 65XX or even a 45XX series switch in their Lans but we all would like have highly available systems. While they are Hardware and Software Load Balancing solutions it would be great to leverage your existing investment in your cisco switches so here is an idea may be able to support Server Load Balancing on a Cisco 35XX series switch.
Let say We need to load balance two MS Exchange 2010 front end servers. First Configure a loopback adaptor on each Server. The IP address of the loopback adaptors will be our chosen Virtual IP address. so lets say our VIP is 172.16.1.1 both loop back adaptors will be assigned this address.
On Your 3560 create two Static Routes pointing to our VIP via the Physical Addresses of the Servers.
# Locate VIP
ip route 172.16.1.1 255.255.0.0 172.16.1.2 with 172.16.1.2 being the address of one of the exchange servers
ip route 172.16.1.1 255.255.0.0 172.16.1.3 with 172.16.1.3 being the address of the second exchange front End
Configure CEF Destination Load Sharing by issuing the command IP load-sharing per-destinantion. This command shares traffic based on source/destination address pairs. We can use IP SLA to track the
reachability of the physical hosts and assign a tracking object to the static route above.
Note I have yet to use the technique above but it should work in theory.