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Some of the Multicast Basics

     

     

    Introduction

    In this document we will discuss few things common in Unicast of the Multicast Basics.

    More information

    Something that is common to the Unicast and Broadcast:

    the count of the destination clients "will always" remain the same, over multiple instants of time

    Example For Unicast Communication

    the number of clients in a unicast communication will always be two.
    
    The count of destination clients in unicast communication will always be 1.

    Example For Broadcast Communication

    say,

    the number of clients in a broadcast domain is X, the count of destination clients in broadcast will always be X
    
    the number of clients in a broadcast domain is X, the count of destination clients in broadcast will always be X
    
    the number of clients in a broadcast domain is Y, the count of destination clients in broadcast will always be Y

    Example For Multicast Communication

    the count of the destination clients "may never" remain the same, over multiple instants of time

    Multicast

    • Client doesn't know who the server is
    • Server doesnt know who the client is
    • both know, who the group is: multicast group, which has ip and mac address

    Multicast Group ensures

    • how to make server ignore, who  all the clients are  , who are interested to listen to what the server is saying
    • how to make client ignore, who the sever is, who is sending the information that the  clients want to listen to

    Controller has to ensure that it is able to IDENTIFY all those clients who want to listen to some mCast data stream. When IGMP Snooping is enabled, the WLC logs each IGMP Join Request and IGMP Join Response in a database called IGMP Report.

    Corresponding to the unique combination of EACH CLIENT and the mCastGroup (in which the client is interested to

    listen), the WLC makes a unique MGID entry for EACH CLIENT. This IGMP report is sent to the infrastructure switch

    (to which the WLC is connected). This report is sent (sourced) from the VLAN (of the client) to the switch.

    if multicast should be supported by the wired network, need to ensure the following(in the wired network):

    [(a)ensure that the device and (b)the concerned n/w interface is configured for multicast)]

    1. Need to ensure that configuration is done

    2. Need to ensure that we can verify if configuration has been done

    1.= (a) ip multicast-routing //  Multicast routing should be enabled Globally in the switch/router

    (b) interface Vlan50

    ip pim dense-mode // PIM should be enabled on each interface corresponding to the N/w

     //  where mcast should be working fine in the wired network 

    2.= (a) sh ip mroute

     Outgoing interface list:

      Vlan50, Forward/Dense

    (b) sh ip pim interface vlan 50

    Address         Interface                 Ver/       Nbr     Query   DR   
    
                                             DR Mode    Count   Intvl   Prior
    
    10.105.135.136   Vlan50                   v2/D       0       30      1   10.105.135.136

    Now, that we know how to enable multicast in a given wired network, we need to know that how do we find that on

    which network, multicast should be enabled.

    Version history
    Revision #:
    2 of 2
    Last update:
    ‎08-29-2017 12:37 AM
    Updated by:
     
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