Disabling steering on the cluster backplane
Supported from NetScaler 11 onwards.
The default behavior of a Citrix ADC cluster is to direct the traffic that it receives (flow receiver) to another node (flow processor) that must then process the traffic. This process of directing the traffic from flow receiver to flow processor occurs over the cluster backplane and is called steering.
If required, you can disable steering so that the process becomes local to the flow receiver and therefore makes the flow receiver as the flow processor. Such a configuration setup can come handy when you have a high latency link.
This configuration is applicable only for striped virtual servers.
- For partially striped virtual servers, if the flow receiver is a non-owner node, the traffic is steered to a owner node. If however, the flow receiver is a owner node, then steering is disabled.
- For spotted virtual servers, flow receiver is the flow processor, and hence there is no need for steering.
Some points to remember when disabling the steering mechanism:
- Striped SNIPs are not supported as steering is disabled.
- MPTCP and FTP does not work.
- L2 mode must be disabled.
- If USIP is enabled, traffic may not reach back to the same node as the steering is disabled.
- Traffic that is directed to the cluster IP address is steered to the configuration coordinator.
- When a node joins or leaves a cluster, it is possible that more than 1/N connections will be affected. This is due to the fact that a change in the nodes available, may cause the routes to be rehashed. As a result, the traffic will be routed to another node and due to the non-availability of steering, the traffic will not be processed.
Steering can be disabled at the individual virtual server level or at the global level. The global configuration takes precedence over the virtual server setting.
Disabling backplane steering for all striped virtual servers
Configured at cluster instance level. Traffic meant for any striped virtual server will not be steered on cluster backplane.
add cluster instance \<clId\> -processLocal ENABLED
Disabling backplane steering for a specific striped virtual server
Configured on a striped virtual server. Traffic meant for the virtual server will not be steered on cluster backplane.
add lb vserver <name> <serviceType> -processLocal ENABLED