Multicasting

AbdulRahman AbdulSalamAhmad AlHammarYousef Yateem

Types of Casting

1. Unicasting: • One-to-one• Easy to implement• Will waste bandwidth if many people demand the same

data.

2. Broadcasting:

3. Multicasting:

Unicasting

Types of Casting

1. Unicasting: • One-to-one• Easy to implement• Will waste bandwidth if many people demand the same

data.

2. Broadcasting:• One-to-all• Good when all request the same data• Bad if some don’t want it

3. Multicasting:• One-to-group• Solves both the problems above• More complicated than the two above

Multicasting

The Basic Idea of Multicasting

Instead of sending a separate copy of the data for each recipient, the source

sends the data only once, and routers along the way to the destinations

make copies as needed.

Why Multicasting?

• Conserves Bandwidth• Consider stats from Victoria Secrets

• More than 1 million web hits during the 1st hour• 283% increase in web traffic during event.

• Enhanced Efficiency: • controls network traffic and reduces CPU loads

• Optimized performance: • eliminates traffic redundancy

• It’s all about the Cost• more bandwidth more costs

Bandwidth Usage for Clients Listening to an 8 Kbps Audio Stream

Multicast vs. Unicast

Multicasting at Transport Layer

• Multicasting uses UDP (User Datagram Protocol) as its underlying transport protocol.

No retransmission of packets or acknowledgment in the TL .

Any reliability must be engineered-in at higher level.

• The more reliable Multicasting forms, do have negative acknowledgments.

Multicasting at Network Layer(IP Multicasting)

1. Addressing • IP addresses Class D• Address the message to Multicast group

2. Group Management• Uses Internet Group Management Protocol (IGMP)

3. Routing• Message goes to Rendez-vous Points (RP)• RPs forward message to devices in domain and other RPs. • The Multicast Routing Protocol used is (PIM-SM)

Shortest Path Tree

Group Member 1

Source

Group Member 2

Rendezvous Point Tree

Group Member 1

Source 1

Group Member 2

Source 2

Rendezvous Point

RP Tree

Shortest Path Trees

Applications that use Multicasting:• Video conferencing

• Corporate communications

• Distance learning

• Distribution of software

• Stock quotes

• News

Sources and refrences• http://www.savetz.com/mbone/ch3_1.html • http://en.wikipedia.org/wiki/Multicasting • http://abilene.internet2.edu/services/multicast.html• http://www.multicasttech.com/ • http://www.internet2.edu/resources/infosheetmulticast.pdf • http://mcast-wiki.internet2.edu/index.php?n=Main.MulticastCookbook • http://www.tcpipguide.com/free/t_IPMulticasting-2.htm • http://www.cisco.com/warp/public/779/largeent/learn/technologies/multicast.

html.

• http://www.cisco.com/warp/public/cc/pd/iosw/prodlit/ipimt_ov.htm • http://www.answers.com/topic/multicast?method=22• http://www.uoregon.edu/~joe/understanding-mpeg1-multicast.pdf • http://www.cisco.com/application/pdf/en/us/guest/products/ps6552/c1161/

cdccont_0900aecd80310883.pdf • ftp://ftpeng.cisco.com/ipmulticast/networkers00/IntroToIPMulticast.pdf• www.iana.org/assignments/multicast-addresses.

http://www.sprintlink.net/multicast/faq.html#JoiningGroups

Questions