HP Traffic Director Server Appliances sa7200/sa7220 and 8200/sa8220 - User Guide

C H A P T E R 2 Routing with Dual Interfaces
27
Routing with
Dual Interfaces
Because the SA8220 has two network interfaces, it can act as a router
in some contexts. This means that it can route between two subnets.
To do this, you must designate the SA8220 as the default gateway for
your fulfillment servers. Routes to the inside subnet are not
advertised to the outside router, but host routes are advertised to the
VIPs. Packets destined for defined VIPs are always routed through
the SA8220 to the server-side subnet. Other packets are forwarded
through the SA8220 only when the security mode is set to OPEN or
when set to CUSTOM and IP Forwarding is turned on. The SA8220’s
routing capabilities vary depending on which routing and failover
methods are used. For more details about these variations and their
relationships to routing and failover configurations, please see
“Failover Method Dependencies” in Appendix C.
NOTE: The SA8220
cannot route multiple
subnets on one interface.
Terms pertinent to SA8220 routing are listed below.
The figure below shows an example of the SA8220 routing topology.
SA8220 Routing Topology
Term Description
Network-side
subnet
The SA8220 interface attached to the side of the
physical network on which client requests arrive.
Server-side
subnet
The SA8220 interface attached to the side of the
physical network that includes the fulfillment
servers.
“Outside”
device
The router or switch one hop from the SA8220 on
the brokered subnet
“Inside”
device
The router or switch one hop from the SA8220 on
the server-side subnet
SA8220
Server
Server
Server
Hub or
Switch
Router
B r oker ed
Subnet
Server-side
Subnet
“O u t s i de ”
Router
“I ns i de” H ub
or S witch
SA8220SA8220
ServerServer
ServerServer
ServerServer
Hub or
Switch
Hub or
Switch
RouterRouter
B r oker ed
Subnet
Server-side
Subnet
“O u t s i de ”
Router
“I ns i de” H ub
or S witch