Specifications

CHAPTER 8

Voice and Video in a Campus Network

Video over IP

Video traffic roughly falls into one of three categories: many-to-many, many-to-few, and few-to-many.

Many-to-many includes interactive video, such as Telepresence, Webex, desktop video conferencing, and other peer-to-

peer video and collaboration applications. The data flow is client-to-client, or MCU-to-client. Bandwidth needs for high

definition video vary during the session but are high-up to 12 Mb/s per location, with compression.

Many-to-few sessions represent IP surveillance cameras. The video flow is from the camera source to a storage location,

from storage to a client, or from the source to a client. These typically require up to 4 Mb/s of bandwidth per camera.

Few-to-many describes the typical streaming video, either from an internal company source or an Internet source. It also

applies to digital signage media. This is the most predictable of all video streams and users typically tolerate less-than-

perfect quality. Traffic flows are from storage-to-client or from server-to-client.

QoS Requirements for Video

Video traffic should be compressed because of its high bandwidth needs, but this causes a lot of variation in network

traffic. A picture that does not change much can compress well, resulting in fairly low bandwidth use. But when there are

a lot of changes in the picture, such as when someone moves or shares a new document, compression does not work as

well, which results in high bandwidth use. In contrast, voice traffic is fairly steady.

Video should be placed in its own queue and might be prioritized depending on company requirements. Consider placing

interactive and streaming video into different queues. Aim to provide no more than 200 ms of latency for most video

applications.

Make sure that there is sufficient bandwidth in the network before adding video applications.

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CCNP SWITCH 642-813 Quick Reference by Denise Donohue

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