Mino – The UC Guy

Microsoft Unified Communications Blog

Lync 2010 Bandwidth Management (CAC)

Posted by Mino on October 8, 2010

Post by Jens Trier Rasmussen


In this post I will show you how to configure CAC or bandwidth management and describe how the user experience will be when making calls where no bandwidth is available.

Imagine the setup below. Two network segments ( and with a router between. Two sites in the topology – Copenhagen and Odense. One user, a Lync Server 2010 SE box and a PSTN Gateway on both segments and the the user is signed in to the local SE box. Both users are UM enabled in a dial plan hosted on the Exchange 2010 SP1 server in Copenhagen.



I want to configure CAC to disable all audio and video between Copenhagen and Odense. In order to do that I use the PS script below:

# Bandwidth PolicyProfile
New-CsNetworkBandwidthPolicyProfile -Identity AllBlocked -AudioBWLimit 0 -AudioBWSessionLimit 200 -VideoBWLimit 0 -VideoBWSessionLimit 3000

# Network Regions
New-CsNetworkRegion -NetworkRegionID DK1 –CentralSite site:cph1 -Description "Copenhagen"
New-CsNetworkRegion -NetworkRegionID DK2 –CentralSite site:od1 -Description "Odense"

# Network Region Links
$a=New-CsNetworkRegionLink -NetworkRegionLinkID rl1 -NetworkRegionID1 DK1 -NetworkRegionID2 DK2 -BWPolicyProfileId AllBlocked

# Network InterRegion Routes
New-CsNetworkInterRegionRoute -InterNetworkRegionRouteID nr1 -NetworkRegionLinks $a.identity -NetworkRegionID1 DK1 -NetworkRegionID2 DK2

# Creates a new CsNetworkSite and assigns that the bandwidth policy we just created
New-CsNetworkSite -NetworkSiteID Cph -Description "Copenhagen" -NetworkRegionID DK1
New-CsNetworkSite -NetworkSiteID Od -Description "Odense" -NetworkRegionID DK2

# Create new CsNetworkSubnets
New-CsNetworkSubnet -SubnetID -MaskBits 24 -Description "Copenhagen" -NetworkSiteId Cph
New-CsNetworkSubnet -SubnetID -MaskBits 24 -Description "Odense" -NetworkSiteId Od

# Setup bandwidth management
Set-CsNetworkConfiguration –EnableBandwidthPolicyCheck $true

Let’s assume that the above configuration is in effect and that Alice and Bob would like to call each other. There is not enough bandwidth available to setup the call and the call experience of Alice and Bob is therefore controlled by two parameters (EnableBWPolicyOverride and AllowPSTNReRouting) in the voice policy, they have been granted. In the table below I’ve described what the call experience will be given different values for the two parameters.



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