Multicast Basics

Till now we discussed about, Multicast and about advantages and disadvantages. Now let’s see some Multicast basics. Which is very important in real time to deal with multicast , we will discuss about Multicast address ranges and reservations.

Basics:

A single host can join multiple Multicast group at same time. ( We can open as many applications on our PC , In same time it will access different multicast groups)

The source will not come to know, who are receivers / host.

Multicast Address Range

• The range of Multicast IP address is Class D – 224.0.0.0 – 239.255.255.255
• Address assignments from within this range are specified in RFC 5771.
• In this range, 224.0.0.1 – 224.0.0.255 is reserved for Network local (communication) address.
• 232.0.0.0/8 is reserved for Source-Specific Multicast
• 233.0.0.0/8 is reserved for GLOP addressing
• 239.0.0.0/8 is Private range for Multicast address, AKA Administratively scoped address.
•  The First four bits of Multicast IP address is 1110.

Well known Multicast addresses - 

224.0.0.5 – All OSPF routers

224.0.0.6 – All OSPF DR’s

224.0.0.9 – All RIPv2 routers

224.0.0.10 – All EIGRP/ IRMP routers

224.0.1.1 – NTP

224.0.0.1 – All Multicast hosts ( If you ping this IP address, The multicast capable host will reply)

224.0.0.2 – All Multicast Routers

224.0.0.4 – All DVMRP Routers

224.0.0.13 – All PIM Routers

Hope this information is helpful for you ... Plz let me konw in case of any queries with mail id. 

Multicasting - Advantages and Disadvantages

 In this section, We will discuss about Multicast, advantages and disadvantages. Till now we have seen what is multicasting and what are the benefits of  using multicasting in network.

Now let’s start with Multicast advantages -

Multicast Advantages:

Available network bandwidth is utilized more efficiently since single stream of data are replaced with a multiple streams locally by using multicast. It will increase the productivity. Below you can see the graph. This will help you to analyse the benefit for Multicast over Unicast.

 Let’s see multicast Disadvantages -

Multicast Disadvantages

Multicast is UDP-based

  Best-effort delivery: Drops are to be expected. Multicast application must not expect reliable delivery of data and should be designed accordingly. Reliable multicast applications will address this issue.

  No congestion avoidance: The lack of the TCP windowing and "slow-start" mechanisms can result in network congestion. If possible, multicast applications should attempt to detect and avoid congestion conditions.

  Duplicates: some multicast protocol mechanisms result in the occasional generation of duplicate packets. Multicast applications should be designed to expect occasional duplicate packets.

  Out-of-sequence delivery: Network topology changes affect the order of delivery -- the application must properly address the issue.

Now we completed, Multicast advantages and disadvantages. It will help you to decide, will it be beneficial for your company/requirements.

For my opinion -

Multicasting is more efficient means, delivering of content where a single sender needs to deliver the content to multiple receivers. This task may be achieved through the use of multicast groups.

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