Considerations for deploying NetCache multicast support

Is multicast the right solution for your organization?

This section will help you determine whether using multicast transmission is the right solution for your organization. Using multicast is just one way of conserving bandwidth. Keep in mind that multicast can be used only for live streams and with network devices that support multicast. For some organizations, prepopulating NetCache appliances with content meets their requirements for bandwidth conservation. See Prefilling streaming media caches for more information.

Organizations that can benefit from using multicast transmission

The following table shows the types of organizations that can benefit from using multicast transmission.

Types of organizations	Usage example
Multicast-enabled enterprises	Considerable bandwidth can be saved if NetCache passes streams to a multicast-enabled network instead of splitting the streams. NetCache can also enable an enterprise to optimize the transmission of Internet traffic. A majority of enterprises have no access to multicast from the Internet, although they might have set up multicast on their intranets. Such enterprises cannot, therefore, obtain a multicast stream through an Internet access point. If a NetCache appliance is set up for multicast and is located at an Internet access point, the appliance can convert unicast transmissions that it receives to multicast. See Scenario: Deploying multicast in an enterprise.
Internet CDNs	Internal bandwidth usage in the CDN data center can be reduced by using multicast. See Scenario: Multicast support for a CDN.
Organizations using a satellite link	Organizations can stream corporate meetings over a satellite link to make them available worldwide, thereby reserving the corporate WAN for business-critical traffic. See Scenario: Multicast support for transmission over a satellite link.
Web sites that NetCache appliances accelerate	Internal bandwidth usage can be reduced by using multicast.

Multicast settings according to client location and activity

The following table helps you determine which multicast settings, if any, are appropriate, depending on the location of clients and their settings for multicast.

If...	Then...
Clients will make requests only from origin servers in the same enterprise domain, and the enterprise domain and clients are set up for multicast	Typically, it is not necessary to configure a NetCache appliance for multicast in this situation. The reason is that the origin servers and clients in the enterprise can already communicate through the multicast channel. However, if your origin servers handle RTSP requests and you want to use NetCache features such as logging and bandwidth management, enable multicast on the NetCache appliance and configure NetCache for multicast output and multicast tunneling.
Clients that are set up for multicast cannot reach an origin server directly, for example, because the origin server is located on the Internet	Enable multicast on the NetCache appliance and configure NetCache for multicast output. Do not set NetCache for multicast input (NetCache will use unicast input by default).

If...

Then...

Clients will make requests only from origin servers in the same enterprise domain, and the enterprise domain and clients are set up for multicast

Typically, it is not necessary to configure a NetCache appliance for multicast in this situation. The reason is that the origin servers and clients in the enterprise can already communicate through the multicast channel.

However, if your origin servers handle RTSP requests and you want to use NetCache features such as logging and bandwidth management, enable multicast on the NetCache appliance and configure NetCache for multicast output and multicast tunneling.

Clients that are set up for multicast cannot reach an origin server directly, for example, because the origin server is located on the Internet

Enable multicast on the NetCache appliance and configure NetCache for multicast output. Do not set NetCache for multicast input (NetCache will use unicast input by default).