HP Traffic Director sa7220 - Manual (Page 25)

C H A P T E R 2 Services
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Layer 4 (HOT) Services
HOT services provide very fast brokering performance. HOT
services are defined in full by their VIP and port number.
In HOT or “Brokered” mode, the SA8220 performs Network Address
Translation (NAT) on all incoming packets passing through the
connection. NAT changes the destination IP address and port of
incoming packets to those of the selected fulfillment server. The
source IP address is modified to be that of the SA8220.
Fulfillment servers can be addressable by IP address, and thus can be
on either local or wide area networks.
By default in HOT mode, the fulfillment server sees all requests as
coming from the SA8220 rather than from the actual client. In some
environments, it may be desirable to have the fulfillment server see
the requests as if they were coming directly from the client. The
Source Address Preservation (SAP) mode of the SA8220 allows this
to happen (see “Source Address Preservation” for more detailed
information).
Layer 7 (RICH) Services (all models except the
SA7200)
The SA8220 allows more flexible service fulfillment for RICH (Real-
time Intelligent Content Handling) services. The service type
“RICH_HTTP” is available on the SA8220 and enables it to make
fulfillment decisions based on the content of the URL of each client
HTTP request. RICH services also include advanced error detection,
and automatic resubmission of HTTP requests under most error
conditions.
As with HOT services above, fulfillment servers can be addressable
by IP address, and thus can be on either local or wide area networks.