Multicasting .. an Overview!for Next Generation Internetpresented by Marvin Hoffmannat Hochschule der Medien Stuttgart 16.01.2012
Who am I?• Marvin Hoffmann (B.Sc.)• Bachelor „Medieninformatik“ at Hochschule der Medien• 2nd semester „Computer Science and Media“
Why this course and topic?• IBM Day some semesters ago - Mr. Demharter spoke about IPv6:• Bachelor courses „With IPv6 there are more adresses • „Nachrichtentechnik“ then grains of sand on earth!“ • „Rechnernetze“ • „Rechnernetze 2“• always curious about new technology• how to adress multiple adresses?• who uses multicasts?
Agenda Questions? When ever they come up!• Introduction • What is it? • Why would I use it?• Multicast • General Information • IPv4 • IPv6 • Problems• Resume
Introduction hat“ an d „why“ The „w of Mult icasting
What is Multicast?• Different approaches of sending information • Unicast • one to one • Anycast • one to one • Broadcast • one to many • Multicast • one to many
Why would I use Multicast?• Multicasting allows you to send the same information to different hosts• .. without having to send it again and again for each of the hosts • Multicast • is not Unicast x n +
Technical Beneﬁts• Enhances Efﬁciency• Increased Scalability• Elimination of Network Redundancy• Reduced Server and CPU Loads‣ Optimized Performance
Business Beneﬁts• Increased Productivity• Reduced Capital and Operational Expense• New Revenue Streams• Increased Competitive Advantage• Network Investment Protection
Multicast and Protocols H ow does it work? What do we nee d?
How it works | General Information• Groupaddress with Subscription-Handling Newsletter Multicast Publisher Sender Subscriber Reciever Mail-Server (Rendezvous-) Router Newsletter-Topic Multicast-Group subscribe to Newsletter Join Multicast-Group unsubscribe from Newsletter Leave Multicast-Group
How it works | IPv4• reserved Address-Space is 22.214.171.124/4 (126.96.36.199 - 188.8.131.52) binary: 1110xxxx.xxxxxxxx.xxxxxxxx.xxxxxxxx• some difﬁculties: • 184.108.40.206/8 is used by Routing-Protocols • 220.127.116.11/8 is used for scoping• uses special Internet Group Management Protocol to handle Join and Leave Requests for Groups
How it works | IPv4Internet Group Management Protocol (IGMP)• used for Group Management• multiple Version (v1 - v3) v1 Host can join MC group; Host can not leave MC group, he times out v2 Hosts can now leave MC group by sending a leave Message v3 a Source for the MC Stream can be speciﬁed on joining a Group• 64 bit Package 0 ... 7 8 ... 15 16 ... 31 Type max. Reply Time Checksum Multicast Group Address• Types: 0x11 Group Membership Query (general or speciﬁc); 0x16 v2 Membership Report; 0x17 Leave Group; 0x22 v3 Membership ReportComplete List of Types can be found here: http://www.networksorcery.com/enp/protocol/igmp.htm
How it works | IPv6• IPv6 Address Format 48 16 64 Public Routing Topology Site T. Interface Identiﬁer network preﬁx host address part• IPv6 Multicast Address Format 8 4 4 112 11111111 Flags Scope FF 0 2 ::1• Flags (0RPT): 0 permanent; 1 (T-Bit) transient; 3 (P-Bit) Unicast-Preﬁx-based; 7 (R-Bit) includes Rendezvous Point address• Scope: 1 interface-local; 2 link-local; 5 site-local; 8 organization-local; E global
How it works | IPv6• IPv6 Multicast Addresses: Address Description Interface-Local Scope FF01::1 all Nodes FF01::2 all Routers Link-Local Scope FF02::1 all Nodes FF02::2 all Routers FF02::D all PIM-Routers FF02::1:2 all DHCP-Servers• IPv6 does not use IGMP anymore, but ICMPv6Complete List of IPv6 Multicast Addresses can be found here: http://www.iana.org/assignments/ipv6-multicast-addresses/ipv6-multicast-addresses.xml
Problems• most Routers in the Internet are not capable of Multicast Routing • special Protocols needed (DVMRP / MOSPF / PIM)• special, world-wide Network called M(ulticast Back)Bone • Tunneling using unicasts from network to network• Routing between Routers with Protocol Independent Multicast (PIM) • best scalability (compared to DVMRP and MOSPF) • Dense-Mode: Broadcast to all Multicast-Routers • Sparse-Mode: Rendezvous-Router who handles Requests (Pub/Sub)