Direct Server Return (Triangulation); Application Redirection (Ar); Ar Overview - Avaya P330 User Manual

Direct Server Return (Triangulation)

Application Redirection (AR)

AR Overview

Avaya P330 Load Balancing Manager User Guide
Direct server return, or triangulation, is an additional implementation of
SLB. In standard SLB, the load balancer intercepts traffic between the
servers and clients in both directions. In triangulation, load balancing is
performed only on traffic from the clients to the server. Traffic from the
servers is returned to the client directly through a router without any
need for load balancing intervention.
For triangulation, the Real Servers must be specially configured. The
Real Servers must also be capable of receiving packets with the Virtual IP
address as the destination IP address, and of sending packets with the
Virtual IP address as the source IP address. The Virtual IP address should
be configured in the Real Servers as a "loopback" IP address, and the
router (not the load balancer) should be configured as the servers'
default gateway.
When the load balancer detects that a Real Server supports triangulation
and is configured properly, it does not change the destination IP address
of the packet. The Virtual IP address is left as the destination IP address,
and the packet does not undergo NAT.
This section provides information about Application Redirection,
including a general overview, and detailed information about Cache
Redirection.
With the growing importance of the Internet as a source of information,
an organization's LAN may suffer from a degradation of performance
due to congestion of the router connecting the network to the Internet.
Since much information retrieved from the Web is either repeatedly
requested by a user or requested by multiple users, many organizations
implement a local caching mechanism to prevent unnecessary Internet
traffic. The local caches must be on the traffic path between the client
and the Internet router. As a result, all traffic, even traffic not intended
for the cache, passes through the cache.
Load balancing solves this problem by redirecting packets from their
original destination to an alternative server based on the Application
Redirection configuration. Cache Redirection is the most common
implementation of Application Redirection.
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