Section 15.5. Summary


15.5. Summary

Communication systems must be able to multicast a message to many users and even route many messages to one user . In a multipoint environment, traditional networks are subject to severe blocking, since they are not typically designed for high-bandwidth communications. Under both multirate and multipoint conditions, the performance of switching networks is closely related to the network architecture.

This chapter focused on multicast techniques, protocols, and algorithms in all levels: from the network layer to the physical layer. After defining some basic terms and techniquesincluding dense-mode and sparse-mode multicast tree algorithms we discussed two main classes of protocols. Intra domain multicast routing protocols multicasts packets within a domain, and the inter domain routing protocol multicasts packets among domains. Among the intradomain protocols is MOSPF, an extension to the unicast OSPF and based on the dense-mode tree algorithm. PIM protocols use sparse-mode tree algorithms.

The inclusion of multicasting capability into modern networks and routers requires considerable sophistication in the architecture and requires a great deal of performance evaluation in both analysis and simulation. Simplistic approaches at the node level can fail to meet the required network performance. A set of multicast algorithms were presented for the router level. The tree-based technique is appropriate for multistage switch fabrics . Multicasting by packet recirculation is a method that reduces switching-network complexity, resulting in less memory required for routing packets in multicast virtual circuits than with tree-based network architecture. However, extra hardware is needed to implement recirculation.

The next chapter looks at some other special-purpose routing situations. One major topic is how two branches of a geographically separate organization can create a secure route by tunneling and establishing a virtual private network (VPN). Other, related topics covered are multiprotocol label switching, point-to-point communications, and overlay networks.



Computer and Communication Networks
Computer and Communication Networks (paperback)
ISBN: 0131389106
EAN: 2147483647
Year: 2007
Pages: 211
Authors: Nader F. Mir

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