HP Traffic Director sa7220 - Manual (Page 26)

C H A P T E R 2 HP Traffic Director Server Appliances User Guide
14
Out-of-Path Return (OPR)
Ordinarily, the SA8220 processes all traffic in both directions
between clients and the server farm. Viewing the server return traffic
helps the SA8220 accurately determine server response times and
handle HTTP errors. Often, the volume of data sent from the server
to the client is much larger than the traffic from client to server, and
checking for HTTP errors is not required. In such situations, you can
use OPR mode to increase performance. OPR is enabled by typing the
following command:
config policygroup service server
port mode [opr]
NOTE: OPR is not
applicable to Layer 7
services. Each server for which OPR is enabled must have its loopback
interface configured to identify itself as the VIP of the brokered
service. This allows the server to respond directly to the client. The
server’s loopback interface, or an equivalent interface that will not
respond to ARP requests, must be configured before setting up the
SA8220 for OPR. For more information, please see “Configuring
Out-of-Path Return in Appendix D.
FTP
Limitations The table below lists those limitations of FTP on the SA8200.
HOT with SAP does not change the server's IP address during Passive
FTP because the server is making the connection directly to the client,
using its real IP address. If the server’s IP address is not a "real" IP
address, this mode will not work.
Mode Active FTP Passive FTP
HOT No Yes
HOT with SAP Yes Yes (see below)
OPR No No