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. Router Backbone Network Corresponding Node Mobile Node AP3 IP-Subnet 1 IP-Subnet 2 AP4 1 2 Mobile Node L2 Handoff L3 Handoff IP1 IP2

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 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. Higher layer Involving higher layers would make solutions more robust and end-to-end. Our Research is based on the end-to-end paradigm with higher layer support for mobility. Uses information from lower layers to achieve high performance loss free handoff. Event based approach with no timer latencies to kick off actions.

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

10. 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.

11. 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. Mobile Node Home Agent Foreign Agent Correspondent Node

12. LL ProbeSNR LL Assoc MIP Movement MIP TCP AAAALT timerCOATunneling LL MIP TunnelingIP-COA TCP IP LL Mobile Node Home Agent Old Foreign agent Correspondent Host Beacon timer Beacon Assoc t t Mobile IP Movement Detection

13. LL ProbeAuthAssoc LL AuthAssoc MIP Registration MIP TCP AAMovementCOATunneling LL MIP TunnelingIP-COA TCP IP LL RT timerCongestion Mobile Node Home Agent New Foreign agent Corresponding Host RT timerCongestion Beacon t t Mobile IP Registration and Tunneling

14. 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.

15. 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

16. 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.

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

18. Interactive Protocol For Mobile networks (2-layer) Mobile Node Link Layer Application layer Handler 3 TCP Event 3 Correspondent Node Application layer Handler 4 Backbone Network Wireless link WIN=0 (freeze) New IP (for destination) Handler 2 WIN > 0 (resume) ` Switch destination IP IP Event 2 Event 1 Link Layer TCP Event 4 IP Future Base Station Current Base Station Get New Base Station Handler 1

19. 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.

20. Handoff in an overlapping cell boundary LL ProbeAuthAssoc LL AuthAssoc IP TCP IP LL PR timer MN Future AP CH 0 win Beacon Application Freeze Handler Auth Handler RealyIP Handler Application OPT=SWITCHIP src_addr OPT=SWITCHIP Application SwitchIP Handler dst_addr ACK ‘OPT’ WakeUp Handler Non 0 win 1 3 4 2 Trns timer Freeze Boundary condition Get BSSID Get NewIP Switch SourceIP WakeUp Switch DestIP Figure 13: IPMN-Fast Handoff Architecture and event sequencing for overlapping cell boundary condition

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

22. Interactive Protocol for Mobile Networks (2- layer Implementation) N od e Ev ent Lay erEvent trackedAction taken by event handler Mobile Node 1LL L2 handoff has been initiated. Advertises a zero window to the FH. The freeze mechanism of TCP will force the FH to stop transmission. 2IP A new IP has been assigned to the MN from the future BS. Call the switch_ip() system call. This will replace the source IP filed in the IP header of the MN with the new IP and will send a segment to the FH with TCP option = SWITCH_IP to replace the destination IP field on the FH. 3 TC P The ‘SWITCH_IP’ segment has been ACKed. Advertises a non-zero window to the FH. This will unfreeze the connection and enable the FH to resume transmission. Fixed Host 4 TC P A special TCP segment received with TCP option=SWITCH_IP. Strip the new IP number from the options part of the segment, then call the switch_IP() system call which stores the new IP in the destination IP field of the IP header overwriting the old IP number.

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

24. 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)

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

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

27. Experiment Setup BS1 Mobile Node Correspondent Node Gateway Switch BS2BS3 Internet 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 Node name LocationIP number Average RTT Hops from MN Local Kent, Ohio 131.123.36.111 ms3 Virginia Chantilly, VA 66.94.95.23690 ms19 Texas Huston, Texas 70.241.64.99183 ms26

28. Voice Call Arrival Distribution Call number Interarrival time (ms) Call Duration Distribution Call number Duration (min) 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.

29. 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.

30. (a) Local node Handoff Latency (seconds) (b) Virginia node Handoff (c) Texas node 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.

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

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

33. Performance Results

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

35. 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.

36. 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.

37. 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...

38. L2 handoff model for 802.11 Link Layer Latency –Probing –Authentication –Association/Re-Association

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

40. 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.

41. L2 Handoff model for 802.11 Authentication –Each successfully scanned channel is tried for authentication until a channel is authenticated. T d : Time For probe transmission P Ta : Authentication Time n : Total Number of tries –one per channel until authentication is succeeded. i : Channel Number that is being authenticated

42. 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. T d : Time For transmission P Tr : Time for state information exchange between Access Points after successful Authentication of that channel

43. 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

44. Modeling IPMN Higher Layer Latency signaling overhead Event Handler overhead Attaining IP Address PR d : proactive registration delay for getting an IP address.

45. 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.

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

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

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

49. Modeling MIP MIP Handoff consists –Movement Detection –Registration –Tunneling MIP Handoff consists

50. 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

51. 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.

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

53. 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.

54. Conclusion Most interesting claim- solution is based on L7 disposable transientware processes. Demonstrated in this case one possible intelligent schema for high performance TCP/IP mobility handling. Further improvements and replacements by more powerful schemes are easy to incorporate– flexibility of L7 transientware. Demonstrated mobility solution did not require any functional change in classical TCP/IP layers. Performance Results indicate the effectiveness and efficiency of our even-based scheme.