Ipv6 Multicasting By : Kaveri Bhaumik

IPv6 Multicasting

• By : Kaveri Bhaumik

• IIT Kanpur

Topics covered are

• Definition of multicasting

• Multicast addresses

• Comparison between IPv4 multicasting & IPv6 multicasting

• VideoLAN Client (VLC) media player

• Advantage of using multicasting in VLC

• Installing VLC

• UDP Streaming With VLC using the GUI

Definition of Multicasting

• Multicast is communication between a single sender and multiple receivers on a network.

• Together with anycast and unicast, multicast is one of the packet types in the Internet Protocol Version 6 (IPv6).

Graphical Representation Of Multicasting

IPv6 ADDRESSING

• There are three types of addresses:

• Unicast: An identifier for a single interface.

• Anycast: An identifier for a set of interfaces and is delivered to one of the interfaces identified by that address.

• Multicast: An identifier for a set of interfaces and is delivered to all interfaces identified by that address.

• Note :-> There are no broadcast addresses in IPv6, their function being superseded by multicast addresses.

Multicast addresses

• Multicast addresses always start with (xx is the scope value)

• ffxy:

• Multicast addresses format:

• | 8 | 4 | 4 | 112 bits |

• +-------------+---+------+---------------------------------------+ |11111111|flgs|scop| group ID |

• +------------+----+------+--------------------------------------+

• Multicast addresses are split into scopes and types

Multicast addresses format…

• 11111111 at the start of the address identifies the address as being a multicast address.

• + - + - + -+ - +

• flgs is a set of 4 flags: | 0 | 0 | 0 | T |

• + - + - + -+ - +

• The high-order 3 flags are reserved.

• T = 0 indicates a permanently-assigned ("well-known") multicast address, assigned by the global internet numbering authority.

• T = 1 indicates a non-permanently-assigned ("transient") multicast address.

Multicast scopes

• ffx1: node-local
• ffx2: link-local
• ffx5: site-local
• ffx8: organization-local
• ffxe: global scope
• others are reserved

Multicast types

• All Nodes Address:

• ID = 1h, addresses all hosts on the local node (ff01:0:0:0:0:0:0:1) or the connected link (ff02:0:0:0:0:0:0:1).

• All Routers Address:

• ID = 2h, addresses all routers on the local node (ff01:0:0:0:0:0:0:2), on the connected link (ff02:0:0:0:0:0:0:2), or on the local site (ff05:0:0:0:0:0:0:2).

Comparison between IPv4 multicasting & IPv6 multicasting

• Although the basic notion of multicasting is common to IPv4 and IPv6, several new characteristics are introduced in IPv6 multicasting.

• In IPv4,multicasting was extension of the basic specification, while specifications of IPv6 require that all IPv6 nodes support multicasting.

• IPv6 explicitly limits the scope of a multicast address by using a fixed address field, whereas the scope was specified using TTL (Time to Live) of a multicast packet in IPv4.

Comparison…

• In IPv4, multicast tunnels were introduced to deploy multicasting .In IPv6,all routers should be multicast-capable, which means that we do not have to use multicast tunnels to deploy IPv6 multicasting.

• IPv4 multicasting use unicast addresses to identify a network interface. However, this is not suitable for IPv6,as an IPv6-capable node may assign multiple addresses on a single interface, which tends to cause a configuration mismatch. In IPv6 ,to identify the interface the user must use specified interface index.

Implementation of multicasting

• We have practically tested multicasting over IPv6 in IITK .

• Muticasting in IPv6 has also been tested across the router using the global scope address .

• For multicast testing we have used VideoLan Client media player which is a freeware.

VideoLAN Client (VLC) media player

• VLC - the cross-platform media player and streaming server.

• VLC is a multimedia player for various audio and video formats (MPEG-1, MPEG-2, MPEG-4, DivX, mp3, ogg, ...) as well as DVDs, VCDs, and various streaming protocols.

• It can also be used as a server to stream in unicast or multicast in IPv4 or IPv6 on a high-bandwidth network.

Advantage of using multicasting in VLC

• Problems encountered using unicast or broadcast are :

• with unicast, when a lot of clients want to receive the stream, the network interface of the server becomes saturated.So the number of clients is very limited, especially when the stream is big.
• with broadcast, the machines that do not want to receive the stream are polluted and some devices do not like to receive huge broadcasts. If you want to send several streams at the same time, the network becomes oversaturated.

Advantage of using multicasting in VLC…

• With multicast, the packets are sent on the network to a multicast IP group which is designated by its IP address.

• The machines can join or leave a multicast group by sending a request to the network. The request is usually sent by the kernel of the operating system.

• The VLC takes care of asking the kernel of the operating system to send the join request.

• It is possible for one client to belong to several groups.

Showing a scenario giving example of multicasting

• Server(vlc) Network Clients(vlc)

• stream --------------> ff1e::1 ---------------> client n°1

• |-------------> client n°2

• Server(vlc) Network Clients(vlc)

• <--------------- client n°3 join

• join ff1e::1

• Server(vlc) Network Clients(vlc)

• |-------------> client n°1

• stream --------------> ff1e::1 ---------------> client n°2

• |-------------> client n°3

Scenario of multicasting…

• Server(vlc) Network Clients(vlc)

• <--------------- client n°1 leave

• leave ff1e::1

• Server(vlc) Network Clients(vlc)

• stream ---------------> ff1e::1 ---------------> client n°2

• |-------------> client n°3

Installing VLC

• For Fedora Core 3 :

• Download the VLC Binaries packages

• vlc-binary.tar.gz

• For Windows :

• Download the self-extracting package

• vlc-0.8.1-win32.exe

• Above packages are available in http://www.videolan.org/

To run the VLC

• Type the following command to run VLC:

• $vlc

• This is the VLC media player:

UDP Streaming With VLC using the GUI

• Server – Send the Data

• Select File – Open File, and Browse to select a file.

• Select the “Stream output” checkbox, then the Settings button – this opens a Stream Output window.

• Output Methods

• For multicasting, select UDP and write following :

• address : ff1e and port : 1234

• Select the checkbox : Play locally

UDP Streaming… Stream Output window

UDP Streaming…

• Client – Receive the Data

• Open VLC on the receiving PC.

• Select File – Open Network Stream.

• To join the session of multicast as sent by

• the server do the following :

• Select UDP/RTP multicast and write :

• address : ff1e and port : 1234

• Click the OK button, and the VLC display window should open.

Reference

• Further information about VLC can be obtained from :

• http://www.videolan.org/

• THANK YOU FOR YOUR ATTENTION

• Any Questions?