Now voice is very different to data.
Voice calls are smooth in that they require a certain amount of bandwidth and they require that all
the time.
They don't burst like a data application's do.
Voice codecs such as G 7 to 9 or G 711 use a certain amount of bandwidth and they need that for the
entire voice call.
So they said to be smooth, they benign.
They don't try and grab bandwidth from other applications, but they are very drop sensitive and very
delay sensitive.
If your voice packets are dropped or delayed, it will affect the voice conversation.
So in a voice over IP scenario, it's very important that packets arrive without a lot of delay and
packets are not dropped.
Voice is transmitted across UDP, so there's no capability to retransmit loss to voice.
These are the one way requirements for voice latency.
Less than 150 milliseconds jitter less than 30 milliseconds lost less than 1% bandwidth.
It does vary depending on the codec used, but as an example, it's in the range 30 kilobits per second,
228 kilobits per second.
Video has characteristics of voice and characteristics of data in that it's bursty and greedy.
A video with a lot of movement requires more bandwidth than a video where there's not a lot of movement.
So as an example, if you were watching a video stream where there's a lot of action on the screen so
people are moving around or cause a racing or an ultimate example would be a video of a fire.
There's a lot of changes on the screen when videoing fire.
It's going to grab a lot of bandwidth and be very bursty.
If you were videoing a stall scene, so as an example, you were videoing a wall on a building with
no movement, the bandwidth requirements would be a lot less.
Video, however, is drop sensitive like voice.
It's delay sensitive like voice and it uses UDP rather than TCP.
So the one way requirements for video are similar to voice delay or latency less than 150 milliseconds
jitter less than 30 milliseconds lost between 0.1 and 1%.
Bandwidth does vary depending on the video stream.
As an example, if you're watching 720 PE or 180 PE or high definition, the bandwidth requirements
can be a lot higher.
But for the CNA will use a value of 384 kilobits per second to 20 plus megabits per second.
So the thing to remember is that video and voice or delay sensitive.
They are drop sensitive.
A lot of data traffic doesn't have those requirements.
So data traffic such as FTP can be dropped, it can be delayed, but voice traffic in a audio stream
or a video conference needs to be prioritized.
So the idea with quality of service is that we're going to give priority to some sessions over other
sessions.
The packets of delay sensitive applications such as voice and video are going to be prioritized over
traffic from non delay sensitive applications such as FTP.
We'll drop FTP packets before we drop voice packets with FTP.
It doesn't matter.
It will retransmit.
But if we did drop voice packets and video packets, it would affect the user experience.
So with quality of service, we are going to create policies and implement policies using quality of
service mechanisms on a network to prioritize certain traffic types over other traffic types.