Cisco Cisco IOS Software Release 12.2(14)ZA

IOS SLB allows you to configure maximum connections for server and firewall load balancing.

For server load balancing, you can configure a limit on the number of active connections that a real 
server is assigned. If the maximum number of connections is reached for a real server, IOS SLB 
automatically switches all further connection requests to other servers until the connection number 
drops below the specified limit.

For firewall load balancing, you can configure a limit on the number of active TCP or UDP 
connections that a firewall farm is assigned. If the maximum number of connections is reached for 
the firewall farm, new connections are dropped until the connection number drops below the 
specified limit.

You can configure more than one firewall farm in each load-balancing device.

Cisco IOS NAT, RFC 1631, allows unregistered “private” IP addresses to connect to the Internet by 
translating them into globally registered IP addresses. As part of this functionality, Cisco IOS NAT can 
be configured to advertise only one address for the entire network to the outside world. This 
configuration provides additional security and network privacy, effectively hiding the entire internal 
network from the world behind that address. NAT has the dual functionality of security and address 
conservation, and is typically implemented in remote access environments.

This section includes information about the following topics:

Session redirection involves redirecting packets to real servers. IOS SLB can operate in one of two 
session redirection modes, dispatched mode or directed mode.

In both dispatched and directed modes, IOS SLB must track connections. Therefore, you must design 
your network so that there is no alternate network path from the real servers to the client that bypasses 
the load-balancing device.