Logo 1 mroute and Traffic Monitor
Monitoring Current State of Multicast Traffic 		Logo 1

Two kinds of analyses are presented in this section: (1)analysis of characteristics of entries in the multicast routing tables, mroutes; and (2)analysis of characteristics of multicast traffic passing through the routers that we collect data from. For a more extensive analysis of multicast routing tables at FIXW-MBONE (fixw-mbone.nsn.nasa.gov) please refer to Bill Fenner's work. Following is a list of graphs available in this section.


List of Available Graphs:
More Info:
Bandwidth Usage Statistics Last One Day Last 24 Hours


Bandwidth Usage Statistics Last One Week Last 1 Week


Bandwidth Usage Statistics Last One Month Last 1 Month
Descriptions of Plots

  • Total Entries
    Total distinct entries (mroutes) in multicast routing tables of the routers that we collect data from. For more information about what these entries signify please look at the note, What is a multicast routing table and what is an "mroute"?


  • MSDP
    Number of mroute-entries for which the (S,G) was advertised via MSDP.


  • Dense Mode
    Number of mroute-entries operating in dense mode.


  • Sparse Mode
    Number of mroute-entries operating in sparse mode.


  • Connected
    Number of mroute-entries for which a member of the group is present on the directly connected interface.


  • Local
    Number of mroute-entries for which the The router itself is a member of the multicast group.


  • Pruned
    Number of mroute-entries which have been pruned and, hence, there is no more forwarding to the downstream members.


Bandwidth Usage Statistics Last One Day Last 24 Hours


Bandwidth Usage Statistics Last One Week Last 1 Week


Bandwidth Usage Statistics Last One Month Last 1 Month
Descriptions of Plots

  • Average Bandwidth Usage
    The amount of bandwidth used at the monitored router by the traffic from active sources. Note: With an increase in the deployment of sparse mode protocols, especially at the interdomain level, not all the traffic passes through all the routers (unlike the "broadcast and prune" routing scenario in dense-mode). The statistics presented here might not even be representative of the actual global picture. The work is in progress for collecting data from more routers across different domains and generating a representative statistics.


What is a multicast routing table and what is an "mroute" ?

Multicast routers maintain state about the incoming and outgoing interfaces for each (S,G) pair --source-group pair. This state is used to decide which packets are to be discarded and which are to be forwarded. The table that router maintains for holding this state information is called multicast routing table. Each entry in this table corresponds to a unique (S,G) and is referred to as mroute. Each mroute primarily contains 4 types of entries: (1)address of the multicast group; (2)address of the corresponding source (or * for all sources); (3)incoming interface; and (4)list of outgoing interfaces.

A hypothetical example: Lets us consider the example of a router that has three interfaces say, Inter-A, Inter-B and Inter-C . Now, consider a scenario where this router has an mroute entry for (S1, G1); i.e. source, S1 and group, G1; such that Inter-A is listed as an incoming-interface and Inter-C is listed as an outgoing-interface. With this entry in its multicast routing table if router receives a packet for (S1, G1) from Inter-A it will forward it to Inter-C. However, if packet is received from any other interface, it will discarded.

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Comments and Suggestions: prash@caida.org

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