Product Documentation

Virtual Inline Mode

Dec 28, 2012
Note: Use virtual inline mode only when both inline mode and WCCP mode are impractical. Do not mix inline and virtual inline modes within the same appliance. However, you can mix virtual inline and WCCP modes within the same appliance. Citrix does not recommend virtual inline mode with routers that do not support health monitoring.

In virtual inline mode, the router uses policy based routing (PBR) rules to redirect incoming and outgoing WAN traffic to the appliance for acceleration, and the appliance forwards the processed packets back to the router. Almost all of the configuration tasks are performed on the router. The only thing to be configured on the appliance is the forwarding method, and the default method is recommended.

Like WCCP, Virtual inline deployment requires no rewiring and no downtime, and it provides a solution for asymmetric routing issues faced in a deployment with two or more WAN links. Unlike WCCP, it contains no built-in status monitoring or health checking, making troubleshooting difficult. WCCP is thus the recommended mode, and virtual inline is recommended only when inline and WCCP modes are both impractical.

Example

The following figure shows a simple network in which all traffic destined for or received from the remote site is redirected to the appliance. In this example, both the local site and remote site use virtual inline mode.

Figure 1. Virtual Inline Example


Following are some configuration details for the network in this example:
  • Endpoint systems have their gateways set to the local router (which is not unique to virtual inline mode).
  • Each router is configured to redirect both incoming and outgoing WAN traffic to the local appliance.
  • Each appliance processes the traffic received from its local router and forwards it back to the router.
  • PBR rules configured on the router prevent routing loops by allowing packets to make only one trip to and from the appliance. The packets that the appliance forwards back to the router are sent to their original (local or remote) destination.
  • Each appliance has its default gateway set to the address of the local router, as usual (on the Configuration: Network Adapters page). The options for forwarding packets back to the router are Return to Ethernet Sender and Send to Gateway.