Specifications

16 Barracuda Load Balancer Administrator’s Guide
Barracuda Load Balancer Terminology
The following is a list of some of the terms used by the Barracuda Load Balancer.
Table 2.1: Barracuda Load Balancer terminology
Term Description
Service A combination of a Virtual IP (VIP) and one or more TCP/UDP ports that the
Service is to listen on. Traffic arriving over the designated port(s) to the
specified Virtual IP is directed to one of the Real Servers that are associated
with a particular Service.
Service Monitor The Service Monitor monitors the availability of the Real Servers. It can be
configured either on a per-Service or per-Real Server basis to use one of
several different methods to establish the availability of a Real Server. If the
Service Monitor finds that no Real Servers are available, you can specify an IP
address to which all traffic for the Service will be routed.
Virtual IP (VIP) The IP address assigned to a specific Service. A client uses the Virtual IP
address to connect to the load-balanced Service. The Virtual IP address must
be different than the WAN or management IP address, and it must be on the
subnet as the WAN IP address.
Real Server One of the systems that perform the actual work of the load-balanced Service.
The Barracuda Load Balancer assigns new connections to it as determined by
the scheduling policy in effect for the Service.
Server Farm A collection of Real Servers.
Client The entity requesting connection to a load-balanced Service. It can be an
external Web browser accessing your load-balanced Web site, or an internal
user connecting to a load-balanced mail server.
Persistence A returning connection is routed to the same Real Server that handled a
previous request from the same client within a specified time. Examples of
Servces that may need persistence settings are Web sites that have shopping
carts or require some sort of login. See Enabling Persistence on page 46 for
more information.
Scheduling policy Specifies how the Barracuda Load Balancer determines which Real Server is
to receive the next connection request. Each Service can be configured with a
different policy.
More information can be found in Selecting a Scheduling Policy on page 47.
Route-Path
Bridge-Path
Deployment modes for the Barracuda Load Balancer. They differ in how the
Real Servers are connected. Details and benefits of each mode can be found
in the sections Route-Path (Recommended) on page 19 and Bridge-Path on
page 21.
Direct Server Return
Option that is enabled on individual Real Servers. However, because it can
affect how a deployment is designed, it is often treated as a mode of its own.
More details on this can be found in the section on
Direct Server Return on
page 22.
Logical Network A collection of systems on an isolatable subnet. In Route-Path mode, for
example, all systems associated with the LAN interface would be in one (or
more) logical network(s) 10.1.1.x, and all systems connected to the WAN
interface would be in another logical network of 192.168.1.x. See Figure 2.1: A
logical network layout using Route-Path on page 17 for an example.