In this chapter, we will cover the following topics:
- Gathering data about your network
- Creating network bandwidth policies
- Adding networks to the topology
- Creating region links and routes
- Enabling CAC
- Preparing servers and clients for DSCP tagging
- Controlling/limiting the port ranges for traffic
- Media bypass
Many admins believe that they can implement Lync in their organization without implementing Quality of Service (QoS) and Call Admission Control (CAC). To some extent, this is true. If the organization is only implementing a Presence (P) and Instant Messaging (IM) solution with the odd Peer to Peer (P2P) audio/video session, it might seem like a huge and costly project to implement QoS and CAC for these services. IM and P do not rely on a real-time protocol for deliverance.
However, not implementing a way to control the traffic can soon enough turn out to be a bad decision. Consider a scenario where Lync is implemented as an IM and P solution. However, over time, users become aware of the audio, video, and sharing capabilities within the product. Slowly, the use of real-time protocols grows until the network can no longer deliver at the required performance. Once the users start depending on audio and video, they will soon notice if a call sounds choppy or strange, or if their video breaks into pixels or freezes entirely.
If the users experience poor quality, there is a real chance that they will stop using the product in favor of other products that they experience fewer issues with (things such as going back to the old physical phone, skipping videos, and avoiding online meetings if a physical one is an option).
This is where QoS and CAC can help an organization. Implementing QoS and CAC are two ways of controlling the flow of traffic throughout the network.
Note
There is no point in implementing QoS or CAC within Lync, unless the rest of the infrastructure is configured accordingly. This, however, is beyond the scope of this chapter and book. QoS and CAC have to be implemented as a cooperative effort with those in control of the network (routers, switches, firewall, and other networking equipment).
This chapter will discuss how to implement QoS and CAC in your Lync deployment; it is not intended as an introduction to QoS and CAC in general. This chapter will go through a set of configurations needed to implement the core concept of QoS and CAC. In-depth information about all the inner workings is beyond the scope of this chapter.
Microsoft has provided a lot of good material that covers the topics of network, QoS, and CAC. The following are some recommended articles that you should be familiar with prior to starting this task:
- The Planning your network article at http://technet.microsoft.com/en-us/library/jj721883.aspx
- The Networking guide article at http://www.microsoft.com/en-us/download/details.aspx?id=39084
- The Wi-Fi guidelines article at http://www.microsoft.com/en-us/download/details.aspx?id=35401
- A list of certified equipment in general can be found at Microsoft's UCOIP at http://www.microsoft.com/en-us/download/details.aspx?id=35401
It is important to plan QoS and CAC implementation with the network administrators in the organization. Devices in the network will need to honor and keep markings in the path of a media stream; these can be (but not limited to) switches, routers, firewalls, and WAN links provided by external carriers.
Lync has a variety of codecs that it uses for different purposes, and the codec that the client selects can also have an impact on the Quality of Experience (QoE) for the end users.
To mitigate network issues, Lync also has a Forward Error Correction (FEC) functionality, which, in a jammed network where clients experience loss of packets, can make the client send a copy of every packet (doubling the load) in order to compensate.
Tip
Read the TechNet article Network bandwidth requirements for media traffic in Lync Server 2013 to get a more comprehensive understanding of the different codecs and their load on the network at http://technet.microsoft.com/en-us/library/jj688118.aspx.
Only by implementing QoS and CAC can we control and guarantee the same codec selection and QoE for every call. The client will choose the "best" available codec based on how much bandwidth we allow through CAC, and configured properly, this will be the same every time.
Most of the Lync configuration for QoS and CAC can be done either in the Lync control panel (CSCP) or in PowerShell. The primary tool for the walkthroughs given here will be Lync CSCP. The reason for this is the flow of the configuration. Almost everything is done in the Network Configuration section, and it is performed left to right.
Note
The first two tabs in Network Configuration are called Global and Location Profile. The Global tab is an exception to the left-to-right rule, and will be covered much later in this chapter. The Location Profile tab is not within the scope of this chapter but rather an important piece of the E-911 deployment.
We will be going through the following tabs:
- Global: This is a tab that turns the CAC and media bypass on/off for the deployment.
- Bandwidth Policy: This is a tab where policies that control bandwidth usages are created and maintained. These policies can be used to limit both single sessions and the total number of sessions (basically by setting Audio Limit x times higher than Audio session limit, where x represents the number of sessions) to and from a Site with a policy applied (and/or videos as well).
- Region: This is a tab where the Region settings are configured. It's possible to allow media to flow through alternate paths (such as over the Internet and between edge servers) through the Enable audio alternate paths or Enable audio alternate paths options within the configuration of each region.
- Site: This is a tab where Site settings are configured. Link the site to a Bandwidth Policy, define which Region a Site belongs to, or set a Location Policy for E-911, if applicable.
- Subnet: This is a tab for all subnets in the deployment. A subnet is configured with a SubnetID (network address) and a Mask. It is also tied to a site here.
- Region Link: This is a tab where two regions are connected as possible paths as well as the given Bandwith policy between them.
- Region Route: This is a tab where actual media paths (routes) between Regions are configured by tying together Region Links. A media call can't traverse outside its defined Region, unless a Region Route between the sites exists.