Selecting a Deployment Mode
The SD-WAN 4100/5100 appliance can be deployed inline or in a one-arm mode. Inline deployments do not require router reconfiguration; one-arm modes do. SD-WAN 4100/5100 offers internal port bypassing (fail-to-wire) to allow traffic to continue flowing in inline mode if the appliance fails.
Only the one-arm WCCP mode (with a single router) is documented currently. Inline mode is not yet documented. Citrix recommends WCCP mode currently.
Different SD-WAN 4100/5100 models offer different numbers of accelerated bridges. Models with multiple accelerated bridges can accelerate multiple inline WAN links. See the specifications sheet for more details, http://www.citrix.com/content/dam/citrix/en_us/documents/products-solutions/SD-WAN-data-sheet.pdf.
Deploying a single SD-WAN 4100/5100 appliance (or high availability pair)
A standalone SD-WAN 4100/5100 appliance can be deployed in either of these two recommended modes:
- Inline, bridged (L2 inline). This closely resembles a standard SD-WAN inline deployment. Packets enter one bridge port and exit the other bridge port.
- One-arm, WCCP. This resembles a standard SD-WAN WCCP deployment.
Citrix also supports the following two modes (which are outside the scope of this document):
- Inline routed. The NetScaler instance uses routing rules instead of bridging rules to determine how to forward packets.
- Virtual inline. This resembles WCCP, but lacks built-in health-checking.
In L2 inline mode, SD-WAN 4100/5100 is placed between your LAN and your WAN router (or other aggregation point at the LAN-WAN boundary). In a one-arm mode, SD-WAN 4100/5100 is connected directly to a dedicated port on your WAN router.
In cases where the WAN router ports are not as fast as the LAN (for example, when the WAN router has gigabit Ethernet, but the LAN has10 gigabit Ethernet), inline mode provides better performance, because its LAN-side traffic is not limited to the speed of the router interface. (Compression allows the LAN-side traffic to be much faster than WAN-bound traffic under favorable conditions.)
- The inline modes require no reconfiguration of your routers, but involves a service disruption when bringing the appliance into service.
- One-arm modes require router reconfiguration but do not require a service disruption.
- Inline mode has higher performance than the other modes.
- One-arm modes are limited to half the speed of the router or switch port they are attached to.
- With WCCP mode, configuring the router to send only a fraction of the WAN traffic to SD-WAN 4100/5100 (as little as the traffic from a single remote site or even a single remote IP address) makes it easy to bring up and test the installation gradually. Inline mode requires that all WAN traffic pass through the appliance.
- WCCP mode requires more configuration of the SD-WAN 4100/5100 appliance than do other modes, but is more standardized and provides more status information on the router.
- The greater control provided by WCCP, and especially the ability to put the deployment into service in stages, makes WCCP the mode of choice for larger, more complex datacenters, especially if there might be a possibility of overloading the SD-WAN 4100/5100 appliance.
- Inline mode is convenient for smaller WAN networks and simpler datacenters. It is most commonly used with the SD-WAN 4100/5100 310 and 500, and more rarely with the larger appliances.
- Cascaded installations should use WCCP.