Rate limiting is a service provider approach to restricting a customer's available bandwidth over a physically faster link.
This can be done in various ways, such as by queuing, or artificially spacing out packets as they traverse the link (time division), thereby restricting throughput.
In some cases, this mechanism is only triggered when a customer's average utilized bitrate crosses a certain threshold. This may behave similar to the way some connections permit brief bursting over the provisioned rate.
Because AppNeta Delivery Path monitoring is extremely light on bandwidth use, path monitoring traffic may not be subject to rate limiting, and may also be able to take advantage of any available bursting. This may skew the result in path Capacity metrics, and Capacity may be showing at a higher rate - such as underlying physical connection, instead of the capacity provisioned by the service provider.
When Rate-limited monitoring (RLM) is enabled, AppNeta instruments the network path with controlled bursts of packets at the total capacity rate in order to trigger the network's rate-limiting mechanism. The source sends packet bursts outbound and the target sends packet bursts inbound. The rate at which the Monitoring Points receive the packet bursts determines the rate-limited capacity. These bursts, though brief, have more impact on the network than AppNeta's standard monitoring techniques, but are required in order to trigger the rate limiting mechanism.
As Rate-limited monitoring (RLM) generates network load, it must be used with caution. To that end, it is not enabled by default and must be enabled by Broadcom Support.