Connection Oriented Mobility Using Edge Point Interactivity

1. Connection Oriented Mobility Using Edge Point Interactivity Sandeep Davu Networking and Media Communications Research Laboratories Computer Science Department Kent State University

2. AGENDA • Problem Statement • Related Work • Proposed Scheme -- IPMN • Implementation 2-Layer IPMN • Performance Analysis • Modeling of 3-Layer IPMN • Conclusion

3. AGENDA • Problem Statement • Mobility Management • Short Comings of current network • More higher layer specific approach needed • Related Work • Proposed Scheme • Performance Analysis • Conclusion

4. Mobility Management • A node is said to be mobile if its point of attachment is flexible within and across networks. • Handoff is the process of changing the point of attachment without losing the connection states. • Handoff classifies into two categories. • L2 handoff –only the point of attachment in LL is required (change of Access Point). • L3 handoff—happens along with L2 handoff where Access Point is in a different subnet. This requires attaining new IP address. Corresponding Node L2 Handoff L3 Handoff Backbone Network IP - Subnet 1 IP - Subnet 2 Router Router AP 1 AP 2 AP 3 AP 4 IP1 IP1 IP2 Mobile Node Mobile Node Mobile Node

5. Short comings of network • OS and network architecture did not envision wireless and mobility. • Error Prone nature of the wireless links – not as rigid as Ethernet. • State full nature of connection oriented networks – robust retransmissions. • A transport layer connection is identified by a four tuple <source address, source port, destination address, destination port> maintained at either end points. • A L3 handoff requires a network address change for the Mobile Node rendering the current TCP connection useless. • Unexpected disconnections and moving end points. • Rapidly Converging 3G and 4G networks and strong need to have seamless mobility • Is there an effective way to handle this???

6. Protocol Re-organization • Principle – Most network complexities are better handled at higher layers and end-systems. • Protocol extension needed for mobility and justifies the design principle employed. • Mobility in wireless networks (802.11 MAC) involves more than one network layer to perform a handoff. • cross-layer interaction between networking layers to achieve high performance loss-free handoffs. • Event based approach with no timer latencies to kick off actions.

7. Are current approaches not enough??? • There are several approaches proposed which address one particular area of mobility • Solutions proposed in one layer (either IP or TCP). • Interoperability between layers was hindered. • Indirect performance implications even if the problem was addressed directly.

8. AGENDA • Problem Statement • Related Work • Network Layer Solutions • Higher Layer Solutions • Mobility Management • Performance Tuning • Proposed Scheme • Performance Analysis • Conclusion

9. Network Layer Solutions • Mobile IP provided the first effective crack in handling mobility. • Route Optimization provides a solution for triangulation problem. • Hint based handoffs used triggers from lower layers as hints to perform fast handoff. • The RAT (Reverse Address Translation) architecture, based on the network address translation (NAT) protocol, uses packet re-direction service between CH and MN to support IP mobility.

10. Mobile IP • Added an indirection to the routing mechanism in the form of Home Agents and Foreign Agents. • Mobile IP Handoff is a two step process • Movement Detection—Detects which Agent will service the MN. • Registration—Registers the Foreign Agent with Home Agent. • Tunneling—HA and FA creates a mutual tunnel to route packets to MN. Correspondent Node Home Agent Foreign Agent Mobile Node

11. Mobile IP Movement Detection Correspondent Host Home Agent Mobile Node MIP IP-COA Tunneling LL TCP TCP Old Foreign agent IP MIP AA COA Tunneling MIP Movement AALT timer t LL Probe LL SNR Beacon LL Assoc Assoc Beacon timer t

12. Corresponding Host Home Agent Mobile Node MIP IP-COA Tunneling LL TCP Congestion RT timer Congestion TCP RT timer New Foreign agent IP AA MIP COA Tunneling Registration MIP Movement t t LL LL Probe Auth Assoc Beacon LL Auth Assoc Mobile IP Registration and Tunneling

13. Higher Level Solutions • Split Connection Approach • I-TCP was a split approach to the end-to-end connection where the connection was split at the Base Station or Access Point. • MSOCKS[8] achieves connection redirection using split connection proxy. • End-to-End Approach • TCP-R is based on an idea- same as ours, renewing the connection to handle the new IP address. • Performance Tuning • Freeze TCP freezes the connection during the course of a handoff by advertising a zero window at the MN.

14. AGENDA • Problem Statement • Related Work • Network Layer Solutions • Proposed Scheme • IPMN Architecture • 2 Layer implementation (experiment and performance) Performance Analysis IPMN 3-Layer Modeling • Conclusion

15. Our Scheme • Uses rapid cross layer interactivity to provide high performance connection oriented mobility support. • Based on the Interactive Transparent Networking (InTraN) paradigm – focused on ordered cross layer interactivity, developed recently in the MediaNet Lab. • Interactive Protocol for Mobile Networks (IPMN) allows event based access to protocol states even by network layer processes or even by L7 processes. • This mobility solution does not require any functional change in the classical TCP/IP network, can avoid FA or HA (thus the need of an infrastructure!), can avoid triangulation, is loss-free, and above all offer much faster handoff.

16. 7 T-ware (1) T-ware (n) T-ware (2) Application user space 1 5 6a TCP Connection Signal Handler 4a Socket API Subscription API Probing API system 3a 4b 2 6b 3b Event Information Kernel Event Monitor Connection State TCP kernel Interactive Transparent Networking

17. Interactive protocol for Mobile networks • Event based approach trapping handoff related events—mostly at L2 like probing, authentication, association. • Probes the link layer and intelligently performs a handoff based on information from L2. • Handoff procedure depends on the cell boundary conditions of the Access Points. • Overlapping – When a MN is being serviced by more than one AP at any given point of time • Non-overlapping – When MN is experiencing temporary periods of disconnections when switching between AP’s. • Does not require an infrastructure – easy to deploy, backward compatible to legacy networks.

18. Handoff in an overlapping cell boundary Mobile Node Correspondent Host Old Access Point Application Unfreeze Handler Application Application SwitchIP Handler RealyIP Handler Auth Handler LL SNR t 4 3 Freeze Handler TCP OPT=SWITCHIP PR timer TCP 0 win ACK ‘OPT’ OPT=SWITCHIP dst_addr Trns timer src_addr Future Access Point Non 0 win IP Application IP 1 t 2 LL LL Auth Assoc Probe LL Auth Assoc Beacon

19. Interactive Protocol for Mobile Networks(2- layer Implementation)

20. Handoff in an non-overlapping cell boundary Mobile Node Correspondent Host Application WakeUp Handler Application SwitchIP Handler RealyIP Handler Auth Handler 4 3 Freeze Handler Switch SourceIP Switch DestIP WakeUp Freeze TCP OPT=SWITCHIP PR timer TCP 0 win ACK ‘OPT’ OPT=SWITCHIP dst_addr Trns timer src_addr Future Access Point Non 0 win 5 IP Application IP New IP Get NewIP 1 Probe Boundary condition LL LL Auth Assoc Probe LL Auth Assoc Beacon

21. Interactive Protocol for Mobile Networks(2- layer Implementation) • Implementation of L4-L7 cross layer interactivity. • Experimented with the manipulation of IP addresses to reflect the address change. • Implemented changes to the kernel on a FreeBSD4.5 OS running on 700MHz Intel Pentium 4 processor. • API calls for subscribing to events and t-ware modifications to the kernel. • Experiments were carried out between different sites (varying geographic distances)

22. Interactive Protocol for Mobile Networks(2- layer Implementation)

23. AGENDA • Problem Statement • Related Work • Network Layer Solutions • Proposed Scheme • Performance Analysis • Experiment Setup • Performance results • Modeling 3-Layer Handoff. • Conclusion

24. Experiment Setup Lab setup consisted of a Mobile Node a switch and three Base station machines running FreeBSD4.5 OS and a gateway to connect to the outside world. Handoff was simulated using the switch unplugging already plugged in BS and plugging in the new BS. MN is always connected to the switch. Three scenarios where we performed the experiments– varying the position of the Correspondent Node each time– locally in the lab, in Texas and in Virginia. The CN generated voice traffic based on the NetSpec Source Models . We also let the MN move along the cyclic path handoff occuring every 2 minutes BS1→BS2→BS3→BS2→BS1 Internet Correspondent Node Gateway BS1 BS2 BS3 Switch Mobile Node

25. Voice Call Duration Distribution Call Arrival Distribution Duration (min) Interarrival time (ms) Call number Call number • voice has been characterized by a constant bit rate (CBR) source. Sampling rate is 8 kHz and each sample is 8 bits. This gives the standard bit rate of 64 Kb/sec for acceptable voice quality. • Inter-arrival time between two calls is exponentially distributed. • To generate a 64 Kb/sec voice stream, talk bursts were generated by a 144-byte blocks separated by 18 ms silence periods.

26. Performance Results • After running the experiment several times on the three nodes we have observed a big difference –up to two orders of magnitude—in handoff latency between IPMN and classic MIP. • IPMN managed to perform handoff in 110 to 200 milliseconds on average while MIP needed between 14 to 44 seconds. • substantial reduction in handoff latency highlights the advantage of event-based protocols like IPMN over timer-based protocols like MIP. • Demonstrates the property by comparing the handoff latencies of the first 5 handoffs at the application level and at the MIP level.

27. (b) Virginia node (a) Local node (c) Texas node Latency (seconds) Handoff Handoff Handoff Performance Results • Comparing the overhead of MIP and Application. • Application cannot immediately recover as soon as handoff is completed. • Strong Reason to have application aware network solutions for smoother transitions.

28. (b) Virginia Node (a) Texas Node Arrival time (seconds) Arrival time (seconds) Block number Block number Performance Results (b) MIP Jitter (a) IPMN Jitter Interarrival time (ms) Interarrival time (ms) Block number Block number

29. Document Size Distribution Document Size (bytes) Document number Performance Results Document size distribution of the first 100 documents. Interarrival times of the first 100 documents.

30. Performance Results

31. AGENDA • Problem Statement • Related Work • Network Layer Solutions • Proposed Scheme • Performance Analysis • Modeling 3-Layer Handoff • Performance Analysis • Conclusion

32. IPMN 3-Layer Handoff • IPMN has L2 and L3 handoffs. • We considered 802.11 as the MAC and modeled the handoff based on 802.11. • TCP based implementation earlier has given enough insight to model the L3 handoff. • Closely observing we found it controlled properly there are some phases in L2 and L3 Handoffs that could be done in parallel. • Events from L2 triggers actions in L3. • Allowing direct access between layer would be a chaos. • Allowing application intervention is the cleanest way for decision making and controlled cross-layer interaction.

33. IPMN 3-Layer Handoff • IPMN has L2 and L3 handoffs. • We considered 802.11 as the MAC and modeled the handoff based on 802.11. • TCP based implementation earlier has given enough insight to model the L3 handoff. • Closely observing we found it controlled properly there are some phases in L2 and L3 Handoffs that could be done in parallel. • Events from L2 triggers actions in L3. • Allowing direct access between layer would be a chaos. • Allowing application intervention is the cleanest way for decision making and controlled cross-layer interaction.

34. Modeling 3-layer IPMN • Divided into two layers • L2 802.11 Handoff • L3 Handoff. • L2 handoff • Probing – Time to Scan the channels and identify a channel that can be used. • Authentication – Once the channel is established the useability of the channel is verified. • Association – The MN will be associated with the Access Point when the state information is transferred from old to new access point. • L3 handoff • Based on the previous experiments ….event notification and t-ware overheads...

35. L2 handoff model for 802.11 • Link Layer Latency • Probing • Authentication • Association/Re-Association

36. L2 Handoff model for 802.11 • Link Layer Latency • Probing (Scan delay) u + e = number of channels – 802.11 has 11-16 channels Tu : Time Spent in used channel + probe RTT Te : Time Spent in empty channel + probe RTT Td : Time For probe transmission ft (t) : characteristic of the channel as a factor of time BER … Transmission rate …

37. L2 Handoff model for 802.11 • Probing Delay • Total Probing delay • Most of the Time spent in a L2 Handoff is in probing. • There are many techniques in L2 Handoff itself to speed up Probing for overall better Handoff.

38. L2 Handoff model for 802.11 • Authentication • Each successfully scanned channel is tried for authentication until a channel is authenticated. Td : Time For probe transmission PTa: Authentication Time n : Total Number of tries –one per channel until authentication is succeeded. i : Channel Number that is being authenticated

39. L2 Handoff model for 802.11 • Association/Reassociation • After successful authentication the MN’s state information is transferred from the old AP to new Access Point. • Re-association is helpful in knowing the current attachment point of the MN as it is moving from old Access Point to new Access Point. Td : Time For transmission PTr: Time for state information exchange between Access Points after successful Authentication of that channel

40. Modeling IPMN • Higher Layer Latency • Signaling Overhead – Time Taken for event notification • Event Handler Overhead – Time Taken by t-ware modules to access event information and/or any internal stored information • Attaining IP address – Application level overhead to get the IP address Events Tracked

41. Modeling IPMN • Higher Layer Latency signaling overhead Event Handler overhead Attaining IP Address PRd: proactive registration delay for getting an IP address.

42. Modeling 3-layer IPMN • Modeled the total IPMN handoff scheme using statistical modeling. • Incorporated the L2 delay as a statistical model and all the signaling delays and the system call delays as constants. • Also modeled Mobile IP’s handoff to have better performance analysis.

43. MN AP TCP LL CH AP TCP LL new AP AP LL Pr req 1 Pr res 1 Pr req n Pr res n E1 Auth req Auth res Freeze E2 Re-Asso req NewIP req Re-Asso res NewIP res Relay IP E3 ACK Relay IP Wake Up (a) Overlapping Cell Boundary Modeling 3-layer IPMN

44. MN AP TCP LL CH AP TCP LL new AP AP LL Pr req 1 Pr res 1 Pr req n Pr res n E1 Auth req Auth res Freeze Re-Asso req Re-Asso res E5 Relay IP ACK Relay IP E3 Wake Up (b) Non-Overlapping Cell Boundary Modeling 3-layer IPMN

45. Modeling IPMN • Total IPMN Handoff Delay for overlapping boundary conditions • Total IPMN Handoff Delay for non-overlapping boundary conditions

46. Modeling MIP • MIP Handoff consists • Movement Detection • Registration • Tunneling • MIP Handoff consists

47. Extensions-performance analysis • Both MIP and IPMN handoffs are simulated using the developed models. • Performed 100 handoffs and averaged them for both overlapping and non-overlapping scenarios in either case. • IPMN had an average handoff delay of only 70ms while MIP had an average delay of 1.37s in overlapping and 1.6s and 2.14s in non-overlapping scenario. MIP1 and MIP2 are versions of MIP with an AA lifetime of 100ms and 1s respectively. MIP2 is the proposed practice. MIP1 though seems to have lower handoff delay it imposes a lot of communication overhead monopolizing the bandwidth

48. Extensions-performance analysis • IPMN always stays closer to No handoff case which has delay only due to BER and congestion--Normal TCP flow if the MN were not shifting cells. • MIP lags behind by approximately 10s delivering voice traffic and 15s in delivering WWW traffic. • Minimal handoff transition delay for IPMN provides seamless connection.

49. AGENDA • Problem Statement • Related Work • Network Layer Solutions • Proposed Scheme • Performance Analysis • Modeling 3 layer IPMN • Conclusion

50. Conclusion • We have presented high performance mobility protocol which uses rapid cross layer interactivity. • Eliminates routing indirection (triangulation) by explicitly specifying the application about the underlying network change. • Flexibly manipulating the underlying network states transparently from L7 to reflect network address changes—thus eliminating the L3 movement detection. • MIP’s timer based rediscovery of already existing state information in lower layers makes it sluggish. • Our scheme uses this and other information from lower layers to intelligently perform handoff– proactive or reactive.