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TNS Policies

Definition

TNS Policy and Procedure

Network Node Components

Requesting TNS Multicast Routing Service

References

TNS Policy on Multicast Routing on the Penn State Integrated Backbone

The purpose of this document is to introduce Telecommunications and Networking Services' (TNS) policy for multicast routing on the Penn State Backbone. This document briefly defines multicast technology, outlines TNS' multicast routing service, says how to request the multicast routing on the Integrated Backbone, identifies some components needed to use multicast, and presents additional references.

This document is intended for Penn State network and systems administrators.

DEFINITION

Multicast: A technique for the efficient distribution of identical packet streams to groups of selected workstations on one or more LANs.

Multicast protocols and routing are quite different from unicast protocols and routing. Unicast is used in single-node to single-node sessions such as: telnet, ftp, and smtp. Multicast, by contrast, delivers potentially identical packets to groups of network nodes from a sender, or from multiple senders. In unicast, the IP address uniquely identifies an individual network node. A single multicast address identifies a group of network nodes and those nodes may reside on different LANs. A block of IP addresses has been reserved for multicast. These are group addresses and are not uniquely assignable to individual network nodes. Furthermore, network nodes may dynamically join and leave multicast groups. Multicast relies on special IP addressing, routers and multicast routing protocols, and multicast software and hardware components in end user platforms.

TNS POLICY AND PROCEDURE

Telecommunications and Networking Services will provide for the proper routing of multicast packets. TNS will configure its backbone equipment to listen to and receive all multicast packets for forwarding. Current standards for multicast routing and group management will also be followed. As multicast technology develops and changes, TNS will follow the standards when they become available and implemented.

Before requesting the service, the network administrator should verify that their LAN has the proper electronics, features and physical configuration to support multicast traffic. Additionally, the LAN electronics must have the multicast features enabled and properly configured. Enabling the multicast service on a LAN that is not equipped or configured to support this type of IP traffic may cause serious degradation of network performance and could result in denial of service to users of the LAN. The following section on Network Node Components provides information on the basic requirements for a LAN to support multicast.

NETWORK NODE COMPONENTS

In addition to requesting multicast routing, a network node may need hardware and software components to use multicast. Some platforms may require operating system changes in order to receive multicast packets. Various software tools are also needed to discover the active groups and to request group membership. Video and audio tools are also necessary to participate in a group. Furthermore, video cameras and microphones may be required in order to originate a session. TNS does not provide any components for network nodes. However, application software is available for a number of different platforms. The references provided below should assist with the search for appropriate multicast network components.

REQUESTING TNS MULTICAST ROUTING SERVICE

Initially, multicast routing is disabled for existing and newly installed backbone connections. The administrative, technical or security contact for a backbone connection must request multicast routing be enabled for their connection. Requests concerning multicast routing are made using the web form “Multicast Routing” option on the Integrated Backbone Services Request Forms page. TNS offers PIM multicast routing, version 1 and version 2. Version 2 is the default unless otherwise specified.

REFERENCES:

• Kumar, Vinay. MBone Interactive Multimedia on the Internet. Indianapolis: New Riders Publishing, 1996.

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