1. CMPE 257 - Wireless and Mobile Networking 1 CMPE 257 Spring 2006 Wireless Internetworking 2 Wireless and Mobile Networks

2. CMPE 257 - Wireless and Mobile Networking 2 Announcements

3. CMPE 257 - Wireless and Mobile Networking 3 Mobile IP (Recapping)

4. CMPE 257 - Wireless and Mobile Networking 4 Mobile IP is the cooperation of three mechanisms: Discovering the care-of address Registering the care-of address Tunneling to the care-of address.

5. CMPE 257 - Wireless and Mobile Networking 5 Example network mobile end-system Internet router end-system FA HA MN home network foreign network (physical home network for the MN) (current physical network for the MN) CN

6. CMPE 257 - Wireless and Mobile Networking 6 Data transfer to the mobile system Internet sender FA HA MN home network foreign network receiver 1 2 3 1. Sender sends to the IP address of MN, HA intercepts packet. 2. HA tunnels packet to COA, here FA, by encapsulation 3. FA forwards the packet to the MN CN

7. CMPE 257 - Wireless and Mobile Networking 7 Data transfer from the mobile system Internet receiver FA HA MN home network foreign network sender 1 1. Sender sends to the IP address of the receiver as usual, FA works as default router CN

8. CMPE 257 - Wireless and Mobile Networking 8 Agent Advertisement HA and FA periodically send advertisement messages into their physical subnets MN listens to these messages and detects, if it is in the home or a foreign network (standard case for home network) MN reads a COA from the FA advertisement messages

9. CMPE 257 - Wireless and Mobile Networking 9 Registration MN signals COA to the HA via the FA, HA acknowledges via FA to MN these actions have to be secured by authentication

10. CMPE 257 - Wireless and Mobile Networking 10 HA Advertisements HA advertises the IP address of the MN. Routers adjust their entries. Packets to the MN are sent to the HA. –Independent of changes in COA/FA.

11. CMPE 257 - Wireless and Mobile Networking 11 Registration t MN FAHA registration request registration request registration reply registration reply

12. CMPE 257 - Wireless and Mobile Networking 12 Encapsulation and Tunneling original IP header original data new datanew IP header outer headerinner headeroriginal data

13. CMPE 257 - Wireless and Mobile Networking 13 Types of Encapsulation Encapsulation of one packet into another as payload –E.g. IPv6 in IPv4 (6Bone), Multicast in Unicast (Mbone) IP-in-IP encapsulation. –Used in Mobile IP. –Tunnel between HA and COA

14. CMPE 257 - Wireless and Mobile Networking 14 IP-in-IP Encapsulation Care-of address COA IP address of HA TTL IP identification IP-in-IPIP checksum flag s fragment offset lengthDS (TOS)ver.IHL IP address of MN IP address of CN TTL IP identification lay. 4 prot.IP checksum flag s fragment offset lengthDS (TOS)ver.IHL TCP/UDP/... payload

15. CMPE 257 - Wireless and Mobile Networking 15 Problems with Mobile IP

16. CMPE 257 - Wireless and Mobile Networking 16 Network Ingress Filtering Filter packets by source address; discard packets coming from the “wrong” place. –Routers accept only “topological correct” addresses. Solution: “reverse” tunneling.

17. CMPE 257 - Wireless and Mobile Networking 17 Reverse tunneling (RFC 3024) Internet receiver FA HA MN home network foreign network sender 3 2 1 1. MN sends to FA 2. FA tunnels packets to HA by encapsulation 3. HA forwards the packet to the receiver. CN

18. CMPE 257 - Wireless and Mobile Networking 18 The Triangle Routing Problem Aka, “dogleg” routing. MH->CH: direct. CH->MH: CH->HA->MH –Inefficient Solution: route optimization. –Deliver binding updates directly to CH.

19. CMPE 257 - Wireless and Mobile Networking 19 Route Optimization Binding caches: –Nodes can keep caches with CoA for MHs. –If node has entry for MH, sends data directly. –Otherwise, “triangulates” with HA. –Binding cache entries have TTL. –HA, FA, or MH can send binding cache updates to CH.

20. CMPE 257 - Wireless and Mobile Networking 20 Route Optimization Issues Security. –Need authentication. MH frequently moving. –Packets on-the-fly during the change can be lost. –New FA informs old FA to avoid packet loss, old FA now forwards remaining packets to new FA – smooth handoffs. –This information also enables the old FA to release resources for the MN.

21. CMPE 257 - Wireless and Mobile Networking 21 Simultaneous Bindings MN can register multiple CoAs with HA. –Why? De-registration. –Explicit. –Implicit.

22. CMPE 257 - Wireless and Mobile Networking 22 Handoffs MH moving among FNs. New CoA registered with HA. Previous FA not necessarily notified. –Old registration will expire. New data delivered to new CoA. In-flight data? –Dropped and retransmitted by upper layers, or –FA notified of new CoA; FA forwards data to new CoA.

23. CMPE 257 - Wireless and Mobile Networking 23 Types of Handoffs MN-initiated: –Handoff managed by MN. –MN measures signal strength to AP. –Decides target AP and switchs over. Network-initiated: –APs decide when to hand over and to whom.

24. CMPE 257 - Wireless and Mobile Networking 24 Hard versus Soft Handoff Hard handoff: only a single active connection between MN and AP. Soft handoff: two active connections during handoff.

25. CMPE 257 - Wireless and Mobile Networking 25 Handoff Signaling Forward handoff: –Target AP contacts current AP to initiate handoff. Backward handoff: –Current AP contacts the target one.

26. CMPE 257 - Wireless and Mobile Networking 26 Handoff Delay 3 components: –Detect need of handoff. –Link establishment between MN and new AP. –Registration with HA. Pre- and post-registration handoffs: –Pre-registration registers MN with HA before handoff. –Post-registration: HA registration happens after handoff.

27. CMPE 257 - Wireless and Mobile Networking 27 Authentication Malicious nodes can infiltrate FNs. Mobile IP registration includes authentication info exchange. –MH-HA. –MH-FA. –HA-FA. Protection against replay attacks. –Timestamp and nonces.

28. CMPE 257 - Wireless and Mobile Networking 28 Mobility Support in IPv6 Mobile IPv6. Route optimization is default. Fields for specifying both CoA and permanent IP address. –No need for encapsulation. Security is integrated and not an add-on. COA can be assigned via auto-configuration (DHCPv6 is one candidate), every node has address auto-configuration. –No need for a separate FA, all routers perform router advertisement which can be used instead of the special agent advertisement; addresses are always co-located. “Soft" hand-over, i.e. without packet loss, between two subnets is supported. MN sends the new CoA to its old router. Old router encapsulates all incoming packets for the MN and forwards them to the new CoA.

29. CMPE 257 - Wireless and Mobile Networking 29 TCP Performance in Mobile-IP (Choong) Investigate throughput performance of TCP over Mobile IP. Determine additional overhead introduced by Mobile IP. Determine how separate mechanisms contribute to overhead: –Tunneling. –Route triangulation. –Fragmentation. –Handover.

30. CMPE 257 - Wireless and Mobile Networking 30 Goal Determine the impact on TCP performance of –Combined overhead sources. –Individual overhead sources.

31. CMPE 257 - Wireless and Mobile Networking 31 Methodology Several scenarios that compound or isolate overhead sources. Compare performance of between scenario pairs. FTP transfer between MH and CH. Metric: TCP throughput.

32. CMPE 257 - Wireless and Mobile Networking 32 Summary of Results Dogleg routing as main cause of TCP throughput degradation. –Solution: route optimization. Handoff is second. –Mobile-IP’s inherent delay in re-establish connectivity with new FA. –Solutions: Increase frequency of router advertisements. Use link-layer information to trigger handoff.

33. CMPE 257 - Wireless and Mobile Networking 33 Mobile IP Resources Mobile IP Working Group http://www.ietf.org/html.charters/mobileip- charter.html IP Mobility Support (RFC 2002) http://www.ietf.org/rfc/rfc2002.txt Charles E. Perkins http://cseng.aw.com/bookdetail.qry?ISBN=0- 201-63469-4&ptype=0 Charlie Perkin’s home page http://www.iprg.nokia.com/~charliep/

34. CMPE 257 - Wireless and Mobile Networking 34 Micro-Mobility Support

35. CMPE 257 - Wireless and Mobile Networking 35 Cellular IP Internet draft [draft-valko-cellularip-oo.txt, 98]. Provides mobility support for frequently moving hosts within a campus or MAN. Can interoperate with Mobile IP to support wide-area mobility.

36. CMPE 257 - Wireless and Mobile Networking 36 Cellular IP Operation CIP Nodes maintain routing entries (soft state) for MNs –Multiple entries possible. –Routing entries updated based on packets sent by MN – reverse path learning – can be done at Layer 2. CIP Gateway: –Mobile IP tunnel endpoint –Initial registration processing. CIP Gateway Internet BSBS MN1MN1 data/control packets from MN 1 Mobile IP BSBS BSBS MN2MN2 packets from MN2 to MN 1

37. CMPE 257 - Wireless and Mobile Networking 37 HAWAII (Handoff-Aware Wireless Access Internet Infrastructure) Operation: –MN obtains co-located CoA and registers with HA. –Handover: MN keeps CoA,new BS answers Reg. Request and updates routers. –MN views BS as foreign agent. BSBS 3 Backbone Router Internet BSBS MNMN BSBS MNMN Crossov er Router DHCP Serve r HA DHCP Mobile IP 1 2 4