Note: This documentation is valid only for appliances that were provisioned from a factory-reset state with the release 7.1 Configuration Wizard. For appliances that have been updated to release 7.1, but not reprovisioned from a factory-reset state, see the release 7.0 documentation.
When you deploy a SD-WAN 4000/5000 appliance in inline mode, pairs of Ethernet ports on the appliance function as accelerated bridges. Traffic flows into one bridge port and out the other. When two sites with appliances communicate, TCP connections between the sites can be accelerated. Traffic that cannot be accelerated is passed through transparently, as if the appliance were not there.
For maximum reliability, the bridge pairs are equipped with a bypass feature that causes the two ports to be connected to each other should the appliance fail or lose power, allowing traffic to continue flowing even during such an outage.
Starting in release 7.1, inline mode depends on the NetScaler “add interfacePair” command to isolate bridge traffic, ensuring that traffic from one bridge pair stays on that pair. In previous releases, this was done with VLAN definitions. Appliances that were provisioned with release 7.1 have this feature enabled by default. Appliances that were upgraded to release 7.1 without reprovisioning retain their old configuration.
Inline mode is currently recommended only for sites where WCCP is not practical, and which have a single WAN link, or have fully independent WAN links that do not use dynamic routing, load-balancing, or fail-over.