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Can you do multicast routing without using a mulitcast protocol?

Can you do multicast routing without using a mulitcast protocol? In other words, can you simply route the multicast packets to an address?
To give a little background, there are three major methodologies for sending out the same information from a single source to multiple recipients. The most common application that requires this type of technology is desktop video conferencing, where a singular feed is distributed to multiple recipients. The first implementation is unicast, where individual packets are sent to each intended recipients, wasting bandwidth and resources. Broadcasting attempts to resolve this bandwidth waste by forwarding a single broadcast packet to all portions of the network. However, with broadcast traffic all hosts receive the traffic including those not intended for the stream. Thus, the creation of multicasting that only sends the streams to a group of intended hosts on the network that have joined the multicast group.

The Internet Group Management Protocol, defined in RFC 1112, is the standard for IP multicasting. In order for multicasting to work properly on the network, all connected devices require the networking hardware to support IGMP.

To address the question, yes there are ways to create IGMP support for devices directly connected to switches that do not directly support IGMP. Install an IGMP server on the switch. This server listens for and receives multicast group messages and forwards multicast streams to the intended recipients. Multiple platforms and operating systems support IGMP server configuration. However, this solution does not scale to multiple devices and should only be considered on a very limited basis. For multi-device IGMP support, the most cost effective alternative is to upgrade the switches to managed, IGMP-enabled switches as creating, maintaining and configuring IGMP servers is cost prohibited.

This was last published in April 2005

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