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  MPLS Multicast Service is a special feature of IP routing in addition to the other routing modes, viz. Unicast (one to one communication) and Broadcast (one to all communication).
In Multicast service, one copy of the message moves out from the source, the network replicates the message to all interested recipients. Additional protocols and routing tables are used to implement this feature in a network.
This is mostly suitable for content distribution like MSOs, stock tickers, video conferencing, real time sharing of information amongst multiple users, typically from single source to multiple destinations.
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  When multicast is enabled in a network, a point in the network is selected to be a kind of Central Point. Initially logical tree structure is created for the MPLS VPN customers in the network with the IP multicast feature. When multicast is enabled in a network, a point in the network is selected as a Central Point. Technically, this point is called the Rendezvous Point (RP).
All Nodes in the network that are enabled for multicast, communicate with the RP. Whenever any node wants a particular stream, it subscribes for the said stream with the RP. Now a source can send a message to the RP (one copy) and this RP forwards the messages on different tree branches ensuring that replication takes place along the path in a way that one copy of the message reaches all the interested receivers.
Now maintaining which set of receivers are interested in what source is a part of multicast operation. This is achieved by the receiver informing the RP that it is interested to become a part of a multicast group. Multicast groups are identified by a Class D IP address i.e. to In case there are no interested receivers along a particular branch, the message is not transmitted on that core link. In this way the implementation of multicast in a network saves precious bandwidth. A network enabled for multicast can take one copy of the message at the source and make copies of the same along the path from source to interested receivers.
Critical Operations: Tree building, Information dissemination, subscription, termination and regular operation.
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Protocols Used:

  • IGMP (Internet Group Management Protocol): This protocol allows for exchange of messages among receivers and nodes in a group in which they are interested to be a part.
  • RP (Rendezvous Point): The fixing of RP can be achieved in 3 ways as below:
    1. Static: The network administrator statically configures RP in all routers that are part of a multicast domain.
    2. Auto-RP: This protocol elects the RP.
    3. BSR: This protocol elects the RP (an open standard)
  • PIM (Protocol Independent Multicast): This protocol is most widespread in multicast networks today and there are two modes as below:-
  • Sparse Mode: The sparse mode is more efficient than dense. In sparse mode the receiver explicitly informs the upstream on its interest in particular groups/ sources.
  • Dense Mode: Dense mode uses the concept of flood and then prune.
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Requirements from the customer:

  • Customer Should have a full fledged CE router with support for IGMP and PIM protocols
  • PIMv2 Sparse Node is preferred. Dense mode can be considered only for low BW applications
  • Multicast VPN is an extension of Layer 3 VPN. Customer must have a clear IP addressing scheme segregating LAN and WAN.
  • For the special application of Multicast, the reverse path bandwidth will be restricted to 1% of the total bandwidth.
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Readiness of BSNL MPLS Network:

  • BSNL’s IP MPLS Core Network is enabled for multicast traffic and already there are many customers running their application successfully over it.
  • Full interop is provided from end-end and Multicast VPN service is provided to our VPN customers
  • All standard protocols are supported and the bespoke network design can be finalized by the MPLS NOC team in consultation with the customer.
  • BW ranging from 64 Kbps to 10 Gpbs (shortly to increase upto 100 Gbps) can be readily provided all over the BSNL MPLS network.
  • BSNL IP MPLS Network with more than 200 PoPs all over the country is ideally suited for meeting any connectivity requirements of the Enterprise Business customer.
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  • First MPLS VPN service provider.
  • Telecom Service Provider with largest network.
  • Available at every corner of INDIA.
  • IS/ISO 9001:2015 certified Network Operation Centre
  • Transparent Billing.
  • Major Business companies are with BSNL.
For tariff and other commercial information, please contact your nearest Commercial Officer of BSNL Office or Enterprise Business unit of SSA/Circle or Head of SSA /Circle of your area.

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