Abstract :
IP multicast is gaining acceptance among service providers as the protocols and infrastructure mature. However, characteristics of multicast traffic remain poorly understood. Using passive OC-12 monitors, we observed multicast traffic on links connecting aggregated customers and peer networks to our native multicast backbone network. We first refined existing traffic flow profiling methodologies via an exploration of temporal differences in multicast packet trains. Based on this framework, we collected multicast flow traces from four geographically dispersed nodes in the Worldcom vBNS network over a one-month period. We present multicast-specific traffic characteristics including packet and flow sizes, fragmentation, sources per group, and address space distribution. Analysis reveals results contrary to prevailing wisdom, including a preponderance of single-packet flows; a highly variable packet size distribution, with many large packets and strong modes; the existence of fragmented multicast traffic; and an insignificant number of simultaneous multiple-source groups. Based on our analysis, we recommend policies for deployment and improvements to protocol implementations.
Keywords :
Internet; monitoring; multicast protocols; telecommunication traffic recording; IP multicast traffic; Worldcom vBNS network; backbone network service; multicast protocols; multiple-source groups; packet trains; passive OC-12 monitors; service providers; single-packet flows; traffic flow profiling; variable packet size distribution; wide-area multicast traffic; Asynchronous transfer mode; Joining processes; Multicast protocols; Optical switches; Peer to peer computing; SONET; Spine; Stability; Telecommunication traffic; Traffic control;
