Perform this optional task to configure bandwidth-based multicast CAC policies. Bandwidth-based multicast CAC policies provide the capability to assign costs to mroutes that are being limited by per interface mroute state limiters. This task can be used to provide bandwidth-based multicast CAC on a per interface basis in network environments where the multicast flows utilize different amounts of bandwidth. Bandwidth-based multicast CAC policies can be applied globally.

Note	You can omit Steps 3 to 7 if you have already configured the per interface mroute state limiters for which to apply costs.

Perform this optional task to monitor per interface mroute state limiters and bandwidth-based multicast CAC policies.

The following example shows how to configure bandwidth-based multicast CAC policies to provide multicast CAC in a network environment where the multicast flows utilize different amounts of bandwidth.

This example uses the topology illustrated in the figure.

Figure 1. Bandwidth-Based CAC for IP Multicast Example Topology

In this example, three content providers are providing TV services across a service provider core. The content providers are broadcasting TV channels that utilize different amounts of bandwidth:

• MPEG-2 SDTV channels--4 Mbps per channel.
• MPEG-2 HDTV channels--18 Mbps per channel.
• MPEG-4 SDTV channels--1.6 Mbps per channel.
• MPEG-4 HDTV channels--6 Mbps per channel.

The service provider needs to provision the fair sharing of bandwidth between these three content providers to its subscribers across Gigabit Ethernet interfaces. The service provider, thus, determines that it needs to provision each Gigabit Ethernet interface on the PE device connected to the DSLAMs as follows:

• 250 Mbps per content provider.
• 250 Mbps for Internet, voice, and VoD services.

The service provider then configures three ACLs:

• acl-CP1-channels--The ACL that defines the channels being offered by the content provider CP1.
• acl-CP2-channels--The ACL that defines the channels being offered by the content provider CP2.
• acl-CP3-channels--The ACL that defines the channels being offered by the content provider CP3.

Because the content providers are broadcasting TV channels that utilize different amounts of bandwidth, the service provider needs to determine the values that need to be configured for the per interface mroute state limiters and bandwidth-based multicast CAC policies to provide the fair sharing of bandwidth required between the content providers.

Prior to the introduction of the Bandwidth-Based CAC for IP Multicast feature, per interface mroute state limiters were based strictly on the number of flows. The introduction of cost multipliers by the Bandwidth-Based CAC for IP Multicast feature expands how per interface mroute state limiters can be defined. Instead of defining the per interface mroute state limiters based on the number of multicast flows, the service provider looks for a common unit of measure and decides to represent the per interface mroute state limiters in kilobits per second (Kbps). The service provider then configures three per interface mroute state limiters, one per content provider. Because the link is a Gigabit, the service provider sets each limit to 250000 (because 250000 Kbps equals 250 Mbps, the number of bits that service provider needs to provision per content provider).

The service provider needs to further provision the fair sharing of bandwidth between the content providers, which can be achieved by configuring bandwidth-based multicast CAC policies. The service provider decides to create four bandwidth-based CAC policies, one policy per channel based on bandwidth. For these policies, the service provider configures the following ACLs:

• acl-MP2SD-channels--Defines all the MPEG-2 SD channels offered by the three content providers.
• acl-MP2HD-channels--Defines all the MPEG-2 HD channels offered by the three content providers.
• acl-MP4SD-channels--Defines all the MPEG-4 SD channels offered by the three content providers.
• acl-MP4HD-channels--Defines all the MPEG-4 HD channels offered by the three content providers.

For each policy, a cost multiplier (represented in Kbps) is defined for each ACL that is based on the bandwidth of the channels defined in the ACL:

• 4000--Represents the 4 Mbps MPEG-2 SD channels.
• 18000--Represents the 18 Mbps MPEG-2 HD channels.
• 1600--Represents the 1.6 Mbps MPEG-4 SD channels.
• 6000--Represents the 6 Mbps MPEG-4 HD channels.

The following configuration example shows how the service provider used per interface mroute state limiters with bandwidth-based multicast CAC policies to provision Gigabit Ethernet interface 0/0 for the fair sharing of bandwidth required between the three content providers:

!
ip multicast limit cost acl-MP2SD-channels 4000
ip multicast limit cost acl-MP2HD-channels 18000
ip multicast limit cost acl-MP4SD-channels 1600
ip multicast limit cost acl-MP4HD-channels 6000
!
.
.
.
!
interface GigabitEthernet0/0
 ip multicast limit out acl-CP1-channels 250000
 ip multicast limit out acl-CP2-channels 250000
 ip multicast limit out acl-CP3-channels 250000
!