Installation guide

CHAPTER
5-1
Device Manager Guide, Cisco ACE 4700 Series Application Control Engine Appliance
OL-26645-02
5
Configuring Virtual Servers
This chapter provides an overview of server load balancing and procedures for configuring virtual
servers for load balancing on an ACE appliance.
Note When you use the ACE CLI to configure named objects (such as a real server, virtual server, parameter
map, class map, health probe, and so on), consider that the Device Manager (DM) supports object names
with an alphanumeric string of 1 to 64 characters, which can include the following special characters:
underscore (_), hyphen (-), dot (.), and asterisk (*). Spaces are not allowed.
If you use the ACE CLI to configure a named object with special characters that the DM does not
support, you may not be able to configure the ACE using DM.
This chapter contains the following topics:
• Load Balancing Overview, page 5-1
• Configuring Virtual Servers, page 5-2
• Managing Virtual Servers, page 5-63
Load Balancing Overview
Server load balancing (SLB) is the process of deciding to which server a load-balancing device should
send a client request for service. For example, a client request can consist of an HTTP GET for a Web
page or an FTP GET to download a file. The job of the load balancer is to select the server that can
successfully fulfill the client request and do so in the shortest amount of time without overloading either
the server or the server farm as a whole.
Depending on the load-balancing algorithm or predictor that you configure, the ACE appliance performs
a series of checks and calculations to determine the server that can best service each client request. The
ACE appliance bases server selection on several factors, including the server with the fewest
connections with respect to load, source or destination address, cookies, URLs, or HTTP headers.
The ACE Appliance Device Manager allows you to configure load balancing as described in the
following topics:
• Virtual servers—See Configuring Virtual Servers, page 5-2.
• Real servers—See Configuring Real Servers, page 6-5.
• Server farms—See Configuring Server Farms, page 6-18.