Use Case: QoS for Voice and Video Applications

Voice and video traffic is particularly sensitive to measurements that the QoS feature shapes and controls, especially latency and jitter. For voice and video transmissions to be audible and clear, voice and video packets cannot be dropped, delayed, or delivered inconsistently. A best practice for voice and video applications, in addition to guaranteeing bandwidth, is to guarantee priority to voice and video traffic.
In this example, employees at a company branch office are experiencing difficulties and unreliability in using video conferencing and Voice over IP (VoIP) technologies to conduct business communications with other branch offices, with partners, and with customers. An IT admin intends to implement QoS in order to address these issues and ensure effective and reliable business communication for the branch employees. Because the admin wants to guarantee QoS to both incoming and outgoing network traffic, he will enable QoS on both the firewall’s internal- and external-facing interfaces.
  1. The admin creates a QoS profile, defining Class 2 so that Class 2 traffic receives real-time priority and on an interface with a maximum bandwidth of 1000 Mbps, is guaranteed a bandwidth of 250 Mbps at all times, including peak periods of network usage.
    Real-time priority is typically recommended for applications affected by latency, and is particularly useful in guaranteeing performance and quality of voice and video applications.
    On the firewall web interface, the admin selects
    Network
    Network Profiles
    Qos Profile
    page, clicks
    Add
    , enters the
    Profile Name
    ensure voip-video traffic and defines Class 2 traffic.
    QoS-voip-video-profile-class2.png
  2. The admin creates a QoS policy to identify voice and video traffic. Because the company does not have one standard voice and video application, the admin wants to ensure QoS is applied to a few applications that are widely and regularly used by employees to communicate with other offices, with partners, and with customers. On the
    Policies
    QoS
    QoS Policy Rule
    Applications
    tab, the admin clicks
    Add
    and opens the
    Application Filter
    window. The admin continues by selecting criteria to filter the applications he wants to apply QoS to, choosing the Subcategory voip-video, and narrowing that down by specifying only voip-video applications that are both low-risk and widely-used.
    The application filter is a dynamic tool that, when used to filter applications in the QoS policy, allows QoS to be applied to all applications that meet the criteria of voip-video, low risk, and widely used at any given time.
    QoS-voip-video-appfilter.png
    The admin names the
    Application Filter
    voip-video-low-risk and includes it in the QoS policy:
    QoS-voip-video-policy-app.png
    The admin names the QoS policy Voice-Video and selects Other Settings to assign all traffic matched to the policy Class 2. He is going to use the Voice-Video QoS policy for both incoming and outgoing QoS traffic, so he sets
    Source
    and
    Destination
    information to
    Any
    :
    QoS-voip-video-policy-view-all.png
  3. Because the admin wants to ensure QoS for both incoming and outgoing voice and video communications, he enables QoS on the network’s external-facing interface (to apply QoS to outgoing communications) and to the internal-facing interface (to apply QoS to incoming communications).
    The admin begins by enabling the QoS profile he created, ensure voice-video traffic (Class 2 in this profile is associated with policy, Voice-Video) on the external-facing interface, in this case, ethernet 1/2.
    QoS-voip-video-interface-internal.png
    He then enables the same QoS profile ensure voip-video traffic on a second interface, the internal-facing interface (in this case, ethernet 1/1).
    QoS-voip-video-interface-external.png
  4. The admin selects
    Network
    QoS
    to confirm that QoS is enabled for both incoming and outgoing voice and video traffic:
    QoS-voip-video-networkview.png
    The admin has successfully enabled QoS on both the network’s internal- and external-facing interfaces. Real-time priority is now ensured for voice and video application traffic as it flows both into and out of the network, ensuring that these communications, which are particularly sensitive to latency and jitter, can be used reliably and effectively to perform both internal and external business communications.

Recommended For You