2) SaaS: A number of organizations have adopted SaaS applications and public cloud services, and lower-cost direct connections to the Internet for branch offices to access the SaaS resources. Applications accessed over the Internet compete for bandwidth with recreational traffic at the branch office, meaning business applications may struggle for needed resources. Data incoming from the corporate data center over a private WAN only exacerbates the problem.
To ensure critical applications perform predictably with a high level of performance it is essential to control less important traffic and to make room on the network for vital data to get through. Placing devices at third-party websites to do outbound QoS is generally not an option, making the point at which traffic enters the corporate network the only possible place to adequately control bandwidth usage.
How is controlling inbound different?
At first glance it may appear that QoS should function the same whether it is deployed on the outbound or the inbound direction. However, there are two subtle but important differences that come into play when controlling application traffic with inbound QoS:
For inbound QoS to function, the inbound traffic control solution must be the point at which traffic is queued -- essentially the bottleneck. Traffic arriving on-site after being rate-limited by an upstream router renders the QoS solution implemented at the receiving location ineffective. The upstream bottleneck is commonly an unmanaged first-in-first-out (FIFO) queue that gives no consideration to the determined business requirements of the receiving organization and especially for latency-sensitive applications such as VoIP will negatively impact the performance.
For an inbound QoS solution to be the authoritative control point for traffic entering a site, it must employ unique techniques to ensure it solely plays the role of traffic shaper. Several key mechanisms help to ensure that incoming applications are accurately controlled and given the bandwidth and priority needed to match the identified requirements of the organization.