This guest blog post is byat Sonus. You can reach him at . We thank Sonus for being a sponsor.
You want to share that desktop in the conference, but you just know the audio will suffer. Adding video will do the same. Or you’re suffering through poor quality audio within the call. We’ve all been there, so let’s investigate a real use case and solution where this doesn’t have to happen.
Quality of Service End-to-End
When it comes to QoS in unified communications (UC), you probably think in terms of CoS values, DSCP marking, low-latency queues, fixed reserved bandwidth, and so on. The reality is these schemes are a static, and hopeful, solution to a very dynamic UC environment.
How about a method that will dynamically control the network based on these dynamic UC requirements, so that when a call is started, or video or desktop added, network resources would be automatically allocated to satisfy the UC demands?
Let’s discuss how this can be accomplished with the Sonus VellOS™ network control platform.
A UC SDN API Integration
SDN is really about automated network control from an application that has specific Quality of Experience (QoE) requirements, along with notification from the network when a requirement can’t be met.
Several IMTC vendors have collaborated on a comprehensive Unified Communication Quality of Experience specification. This document specifies the requirements for meeting QoE expectations, along with the automation of the network control to realize them. Microsoft has developed and implemented a practical Skype for Business UC SDN API based upon this specification, and contributed a specification within the Open Networking Foundation (ONF).
Skype for Business provides the path intent, names the endpoints, and specifies the attributes of the connection (such as codec used and bandwidth required). In-call updates for bandwidth changes due to codec, addition of video, or desktop sharing, can then be used to dynamically change the network resource control without affecting the call in progress.
VellOS™ then takes this information, reconciles the resources among all other network paths, and directly programs the network devices to meet the requirements of the end-to-end connection.
VellOS™ can inform applications like Skype for Business that requirements can’t be met, or that network resources have changed. The application can determine if it wishes to continue in a best-effort mode, or reject the call. Network policy can dictate (and dynamically change) the importance of the application traffic. In this case, VellOS™ can inform applications of this change, allowing them to adapt.
In cases of network failures where a new path can’t be found, VellOS™ can provide this additional information for increased visibility and failure determination.
You’re reading this because too much networking is never enough, so let’s
discuss some of the implementation details.
The Skype for Business cluster is comprised of a Back End server, a Front End server, and the SDN Manager (LSM) that connects the Skype for Business cluster to the VellOS™ cluster. The Skype for Business client communicates with the Skype for Business cluster, and the configuration can support multiple network instances (tenants, branch offices, and so on).
Information provided over the UC SDN API is used to configure media paths directly in the network. VellOS™ configures the network switches for the path, ensures bandwidth, and provides transparent recovery of failures.
There are also signaling paths that exist between endpoints and the Skype for Business server. The endpoints simply communicate via the media path in the network. Should a network device or link fail, as indicated by the X in the diagram above, VellOS™ will automatically and transparently compute and install a new path nearly instantly.
Because the UC media traffic is encrypted UDP, traditional methods of packet inspection and stateful firewalls are ineffective. The VellOS™network control allows only those packets to travel that are known to be part of the media, which are also metered to ensure they don’t exceed bandwidth requirements.
When the call is complete (or any portion of it is removed, like desktop or video), these UDP ports no longer match any data path, so any packets arriving at the network edge are dropped at that point.
The combination of the application’s awareness of the resources required, and the ability of VellOS™ to control the network resources, provides a level of quality and network efficiency that can’t be achieved with legacy networks. In addition to providing the Quality of Experience, the security features of whitelisted traffic and DoS mitigation are inherently available.
The Network Control
An important feature to understand is VellOS™ is a pure L4-L0 network control design. VellOS™ directly controls the switches in the data path to ensure quality of service and security requirements are met. Overlay solutions can’t provide this level of control for quality or security, as they rely on the underlying (and often uncontrolled) network for transport.
VellOS™ can function and bring value in a hybrid network by providing these capabilities at the edges of the cloud, corporate offices, or branch offices. This precise control at the edges can ensure intermediate legacy links are used efficiently.
Although this is one use case for UC traffic control, all of the many VellOS™ features are always available, providing the expected network control with a mix of applications and dynamically changing requirements. The entire data plane is controlled such that resources are maximized, and all network uses are coordinated to meet data path requirements. You no longer have to worry that an engineer will start a huge file transfer that affects the quality of the CEO’s conference call.
There’s More Beyond QoE
Although the QoE of the conference call media was the intention of the UC SDN API specification, there are a variety of other Skype for Business use cases.
Service providers use the Skype for Business API along with VellOS™ to ensure security and isolation among tenants in their networks, especially at that critical public/private junction in the network cloud. With knowledge of the expected data traffic behavior, VellOS™ can enable access policy dynamically, at the very edge of the cloud.
Microsoft created a feature-rich API with the Skype for Business UC SDN API. Any application can utilize this with VellOS™ to greatly increase the quality and efficiency of network resources.
This is one example of how VellOS™ enables a new world of network control capabilities.