Table of Contents

Server Load Balancing for VPN Clients

The Cisco IOS server load balancing (SLB) feature is an IOS-based solution that provides IP server load balancing. Using the IOS SLB feature, you can define a virtual server that represents a group of real servers in a cluster of network servers known as a server farm. In this environment, the clients connect to the IP address of the virtual server. When a client initiates a connection to the virtual server, the IOS SLB function chooses a real server for the connection based on a configured load-balancing algorithm.

For more information on server load balancing, see http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121limit/121e/121e9/iossl b9e.htm#2711438.

In the Cisco network-based IPSec VPN solution release 1.5, server load balancing is necessary to distribute a large number of IPSec tunnels over multiple IOS devices.

A Cisco NPE-400 with VAM can accommodate up to 1500 clients or layer 2 tunnels. The Cisco network-based IPSec VPN solution release 1.5 can be scaled up using multiple Cisco 7200 routers stacked behind a load-balancer.

Below is a sample configuration for server load balancing that uses a Cisco Catalyst 6500 switch with the SLB feature to distribute the client tunnels. It also provides related configurations for two Cisco 7200 routers used in the configuration.

If any server (7200) fails, purge the connection from database.

This is a reference to probe method defined above.

The real server address.

You can change the weight to divide IPSec tunnels unequally.

This is the maximum connections to this server.

This is the virtual server address.

The sticky group is defined to connect IPSec, IKE, and NAT-transparency together.

This is the uplink to the Internet gateway.

This is the connection to the first Cisco 7200 router.

First Server is Cisco 7200 series router.

Make sure you define TDP ID.

Loopback 1 address is used.

Address is different on both Cisco 7200 routers.

Address is the same as virtual address defined on SLB.

Private or internal address.

Posted: Tue May 20 12:27:39 PDT 2003
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