Christophe Jelger Post-doctoral researcher Christophe.Jelger@unibas.ch

1. IP MulticastingandMobile IP Christophe Jelger Post-doctoral researcher Christophe.Jelger@unibas.ch Christophe Jelger – CS221 Network and Security - Universität Basel - 2005

2. Plan • IP Multicast • General concept • Subscriptions (IGMP, MLD) • Multicast routing • Shared trees • Source-based trees • Mobile IP • General concept • Mobile IPv4 • Mobile IPv6 Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

3. IP Multicast Group communications at the network layer IP Multicast Mobile IP Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

4. 011010 011010 011010 011010 Unicast streaming Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

5. 011010 011010 011010 011010 011010 011010 011010 Multicast streaming Multicast Tree Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

6. IP Multicast: address range (see http://www.iana.org) • IPv4 • Class-D addresses: 224.0.0.0 to 239.255.255.255 (224.0.0.0/28, or 16 Class-A networks !) • Some special addresses … • 224.0.0.1 = all multicast-capable hosts • 224.0.0.2 = all multicast routers • 224.0.0.13 = all PIM routers • IPv6 • ff0x::/8 where x is the scope (2=local, 5=site, e=global) • Some special addresses … • ff02::1 all nodes on link, ff02::2 all routers on link • ff02::16 all MLDv2 multicast routers • ff02::d all PIM multicast routers Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

7. IP Multicast: IP to Ethernet mapping • IPv4 • Ethernet multicast (first 24 bits): 01:00:5E + 0 for 25th bit •  23 bits available to map the IPv4 address to an Ethernet address •  the least significant bits are mapped • Ex: 224.129.47.23  01:00:5E:01:2F:17 • IPv6 • Ethernet multicast (first 16 bits): 33:33 •  32 bits available to map the IPv6 address •  the least significant bits are mapped • Ex: ff05::207:85ff:fe92:7ff8  33:33:fe:92:7f:f8 • In both cases, the Ethernet layer acts as an imperfect filter Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

8. IP Multicast: Step 1  group subscription • IPv4 : Internet Group Membership Protocol (IGMP) • IPv6 : Multicast Listener Discovery (MLD) • Objective: a multicast router must periodically discover nodes that want to join a certain group • The router can then join the appropriate multicast delivery tree • The router only needs to know if there is some interest for a group: it does not need to know exactly how many nodes are interested • There exists different versions of IGMP and MLD: the main difference is the ability to perform "source-filtering" (so that only the traffic sent by a (some) given source(s) is received) Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

9. IP Multicast: group subscription with MLD(subscription with IGMP is similar) JOIN multicast group ff0e::1234:5678 Group: ff0e::1234:5678/64  MAC : 33:33:12:34:56:78 Multicast router MLD Query MLD Report ff0e::1234:5678 Multicast DATA sent to 33:33:12:34:56:78 / ff0e::1234:5678 Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

10. IP Multicast: Step 2  Multicast routing • Objective is to build the multicast delivery tree(s) • Two families of trees: • Shared-trees (*,G): the tree is shared by all (*) multicast sources sending to group G • Source-based trees (S,G): only a given source S can send multicast data on the delivery tree for group G • There has been many protocols for multicast routing, but today the only protocol deployed is PIM: • Protocol Independent Multicast • PIM-SM: Sparse-Mode (shared trees) • PIM-SSM: Source-Specific Multicast (source-based trees) Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

11. 2 2 5 5 (S1,G) (S1,G) 1 1 3 3 6 6 (*,G) 6 6 7 7 7 7 (S2,G) 4 4 IP Multicast: Step 2  Multicast routing Source-based tree (PIM-SSM) Shared tree (PIM-SM) Source S1 Source S1 2 5 2 5 Rendez-Vous Point 1 1 1 1 3 3 6 6 4 4 7 7 Source S2 PIM router with group member(s) PIM JOIN message

12. IP Multicast: some conclusions • IP Multicast is very suitable for • Group communications with multiple sources and receivers (shared tree): known as N-to-M communication • Video-conferencing, network games • Group communications with one source and multiple receivers (source-based tree): known as 1-to-M communication • TV and radio streaming, content distribution • Current deployment of IP Multicast is not large • Lack of security: a misbehaving user can create forwarding states by joining hundreds of groups • Billing: who should pay for what ? • Source discovery accross AS (Autonomous Systems) is complex Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

13. Mobile IP Adding mobility at the network layer IP Multicast Mobile IP Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

14. Users are becoming mobile World-wide availability of popular wireless communication technologies More and more portable wireless devices are also available, and they become really powerful Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

15. Mobile IP • Problems introduced by mobility • When a mobile node moves to a visited network, how is it possible to reach it again ? • What about current on-going connections ? (with TCP, IP addresses partly identifies a connection) • Objectives of Mobile IP • To permit that a mobile node becomes reachable when it is in a visited network • To allow on-going connections to be maintained when the mobile node is moving Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

16. Mobile IPv6: basic mechanisms Binding Update Message (H@  CoA) Home network Internet Access point Home agent Visited network The mobile node main address is the home address (H@) Correspondant Sending to H@ The mobile node obtains an address in the visited network: the care-of address (CoA) Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

17. Mobile IPv6: route optimization Binding Update Message (H@  CoA) Home network Internet Access point Home agent Visited network Correspondant Correspondant Sending to H@ via CoA Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

18. Mobile IP: maintaining TCP connections • IPv4: tunneling • A packet sent by or to the mobile node's home address is encapsulated in another packet sent by or to the CoA • IPv6: routing header and home address option • Via the home agent, tunneling is used • With route optimization, a packet sent to the mobile node's home address is replaced by a packet sent to the CoA which also contains a routing header equal to the H@ • A packet sent by the mobile node always uses the CoA as source address, and it contains a home address option equal to H@ Christophe Jelger – CS221 Network and Security - Universität Basel - 2007

19. Mobile IP: some conclusions • Deployment • Mobile IP has failed to be widely deployed because until recently it suffered from serious security problems: authentication is indeed critical so that a malicious user cannot register a bogus CoA with a home agent • Usage • The "always-on" paradigm is not a reality yet • The need for Mobile IP is not mature enough Christophe Jelger – CS221 Network and Security - Universität Basel - 2007