QOS on routers - bandwidth needed

[ohareka70]

Hello,

I have 8 video conference devices on my network across the LAN/WAN on my private network.  Each site has around 200MB into it.  How much bandwidth should i allocate on each router for QOS (Quality of Service) so that i dont get any 'freezes' with the video picture.

regards,

Kevin

[Wayne DeNardi]

That'd depend on how many simultaneous calls you're expecting and what the call rate for each of the calls is.

If you have, for example, 8 calls @ 1024k, then you'd obviously need 8x1024 = 8Mbps.

Note: QoS really only kicks in when the bandwidth on the link is 100% saturated.

[mayank.sharma · Accepted solution]

Hi Kevin,

My understanding is such..

Firstly... Bandwidth is always symmetric for VC . If you need 1Mbps download for a call, then you also need 1Mbps upload.

Before you place video traffic on a network, ensure that adequate bandwidth exists for all necessary applications. First, calculate the minimum bandwidth requirements for each major application, for example, voice, video, and data. The sum represents the minimum bandwidth requirement for any specific link. This amount should consume no more than 75 percent of the total bandwidth available on that link. This 75 percent rule assumes that some bandwidth is necessary for overhead traffic.

Examples of overhead traffic include routing protocol updates and Layer 2 keepalives, as well as additional applications, such as e-mail and HTTP traffic. Have voice and video traffic occupy no more than 33 percent of link capacity

.

Secondly assuming (worst case scenario) that all your 8 VC devices are located at one site and you have a MCU located at HQ. And all these device are involved in a 1024 (1 Meg) Call on the MCU, then this will take up 8x1024 = 8Mbps x 2 = 16Mbps of your link. Obviously if the your VC units are spread out at diffrent sites then this value becomes less accordingly.

Hope this helps.

[cgiovann01]

I have 65+ end points + two T3 immersive rooms, and 5 custom C90 integrator Multi screen Multi camera AV integrated rooms. I would suggest looking at over all design not just QoS. If you don't have QoS configured for video you should be using AF41(34) for your codecs for both voice and video as your starting point.

Depending on how many end points are going to communicate at the same time, and at what quality, will really dictate the speed needed. For example: 8 end points at a 1080p with encryption you can have great picture quality at about 3072kbps per codec. Without encryption same call 2560Kbps per codec. 720p we have great video at 1700 Kbps per Codec.. The speeds are what we have established and programmed as our "Default call rate" for our network.

A lot has to do with your network, how are the end points wired into the network I.e direct to your core or several layers deep? Do you have an MPLS WAN? Do you have a Multi carrier network, are you using dual CE routers, is the video in its own VLAN? What switches are your Codecs connected?. Every network is different so you can try using the numbers I gave you as a starting point. T3 rooms have 3 Codecs so factor that in if you have them. We dedicate 12 Mbps per T3 room.

With aggregation, you have to factor in how many call at one time will you want to support on your bridge. Also factor in overhead for the type of transport like Ethernet, and 20% increase of bandwidth for encryption if your using it. Think about the media sharing like natural presenter. My numbers cover the use of media sharing with a weighted value of 8v,2P We use C40, C60s, and 90s, we have Ex90s as end points besides our big T3 rooms. You can always contract some Professional services from Cisco for network readiness as well as design assessments. Hope this is helpful

Sent from Cisco Technical Support iPad App

[ohareka70]

Hi cqiovann01,

Here is some more detail in case you have any more advice.

The Polycom is situated 1 hop off the core at each location

We use point to point links (200 MB radio at each site but 45 MB across the core) on our network

We use 2911 routers and Layer 3 switches 3560

Video conference devices are connected into the Layer 2 switches (user LAN)

I was thinking of allocating around 4MB all the way across the network for Video Conferencing (we only have 8 video conferencing devices across 6 of our sites

I think i need to test this in a lab environment before i roll this out on the network

regards,

Kevin