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Connection Oriented Mobility Using Edge Point Interactivity Sandeep Davu Networking and Media Communications Research Laboratories Computer Science Department Kent State University AGENDA • • • • • • • Problem Statement Related Work Proposed Scheme -- IPMN Implementation 2-Layer IPMN Performance Analysis Modeling of 3-Layer IPMN Conclusion AGENDA • Problem Statement – Mobility Management – Short Comings of current network – More higher layer specific approach needed • • • • Related Work Proposed Scheme Performance Analysis Conclusion 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 AP1 IP1 Router AP2 IP1 Mobile Node Mobile Node AP3 AP4 IP2 Mobile Node 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??? 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. 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. AGENDA • Problem Statement • Related Work – Network Layer Solutions – Higher Layer Solutions • Mobility Management • Performance Tuning • Proposed Scheme • Performance Analysis • Conclusion 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 redirection service between CH and MN to support IP mobility. 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 Mobile IP Movement Detection Correspondent Host Home Agent IP-COA Mobile Node Tunneling MIP LL TCP TCP Old Foreign agent AA IP COA Tunneling Movement MIP AALT timer MIP t Probe LL Beacon Assoc SNR Beacon timer Assoc LL LL t Mobile IP Registration and Tunneling Corresponding Host Home Agent IP-COA Mobile Node Tunneling MIP LL Congestion RT timer Congestion TCP RT timer TCP New Foreign agent AA IP COA Tunneling Registration MIP Movement MIP t t Probe LL Beacon Auth Auth Assoc LL LL Assoc 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. 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 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. user space Interactive Transparent Networking 7 T-ware (1) Application TCP Connection Socket API 1 5 6a Signal Handler Subscription API Kernel 4a Probing API 3a 4b 2 TCP kernel T-ware (n) T-ware (2) Event Monitor 3b Event Information 6b Connection State 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. Handoff in an overlapping cell boundary Correspondent Host Mobile Node Old Access Point Unfreeze Handler Application SwitchIP Handler RealyIP Handler Auth Handler t SNR 4 3 LL Freeze Handler Application Application OPT=SWITCHIP PR timer 0 win ACK ‘OPT’ OPT=SWITCHIP dst_addr TCP Trns timer src_addr Future Access Point TCP Non 0 win Application IP 1 IP t Beacon LL Auth LL Assoc 2 Probe Auth LL Assoc Interactive Protocol for Mobile Networks (2- layer Implementation) N od e Ev ent 1 Mobile Node 2 3 Fixed Host 4 Lay er Event tracked Action taken by event handler L2 handoff has been initiated. Advertises a zero window to the FH. The freeze mechanism of TCP will force the FH to stop transmission. IP 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. 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. 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. LL TC P Handoff in an non-overlapping cell boundary Mobile Node Correspondent Host WakeUp Handler SwitchIP Handler RealyIP Handler Freeze Handler Application Freeze Switch DestIP 4 3 Application OPT=SWITCHIP PR timer 0 win ACK ‘OPT’ OPT=SWITCHIP dst_addr TCP Trns timer src_addr 5 1 Beacon LL New IP Application IP Auth LL Assoc Probe IP Auth LL Assoc Get NewIP TCP Non 0 win Probe Boundary condition Future Access Point WakeUp Switch SourceIP Auth Handler 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) Interactive Protocol for Mobile Networks (2- layer Implementation) Table-2 API Extesnion AGENDA • • • • • Problem Statement Related Work Network Layer Solutions Proposed Scheme Performance Analysis – Experiment Setup – Performance results • Modeling 3-Layer Handoff. • Conclusion 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 IP number Average RTT Hops from MN Kent, Ohio 131.123.36.11 1 ms 3 Virginia Chantilly , VA 66.94.95.236 90 ms 19 Texas Huston, Texas 70.241.64.99 183 ms 26 Node name Location Local Voice Call Duration Distribution Call Arrival Distribution 30 3000 L2 = 0.003334 25 2500 Duration (min) 2000 Interarrival time (ms) L1 = 0.004168 1500 20 15 1000 10 500 5 0 L3 = 0.002778 0 1 11 21 31 Call number 41 51 61 71 1 11 21 31 41 Call number 51 61 • 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. 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. TABLE-4. HANDOFF LATENCIES (IN MS) OF THE FIRST FIVE HANDOFFS Handoff 1 2 3 4 5 Average Local IPMN 106 107 111 115 109 110 Virginia MIP 12654 7124 1524 48945 1008 14251 IPMN 114 106 106 111 121 112 Texas MIP 58669 24975 22672 77414 30772 42900 IPMN 202 193 195 195 200 197 MIP 51359 33187 29099 63523 41676 43769 Performance Results (b) Virginia node (a) Local node (c) Texas node 100 100 80 MIP level latency 80 80 Application level latency 60 60 Latency (seconds) 60 40 40 20 20 40 0 20 0 0 1 2 3 Handoff 4 5 1 2 3 Handoff 4 5 1 2 3 Handoff 4 5 • 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. Performance Results (b) Virginia Node (a) Texas Node 300 800 IPMN IPMN MIP MIP Arrival time (seconds) Arrival time (seconds) 250 600 400 200 150 100 200 50 0 0 1 5001 10001 15001 20001 1 5001 10001 Block number 20001 (b) MIP Jitter (a) IPMN Jitter 150 150 130 130 110 110 Interarrival time (ms) Interarrival time (ms) 15001 Block number 90 70 50 30 90 70 50 30 10 10 1 3001 6001 9001 Block number 12001 15001 1 3001 6001 9001 Block number 12001 15001 Performance Results Document Size Distribution 5000 10000000 Lam1=0.000001 Lam2=0.000005 Alpha1=0.4 Alpha2=0.55 4000 Document Size (bytes) 1000000 3000 2000 100000 10000 1000 1000 0 1 21 41 61 81 101 1 21 41 61 81 Document number Document size distribution of the first 100 documents. f X ( x) ex , 1 / mean Interarrival times of the first 100 documents. k FX ( x) 1 x f X ( x) k x 1 0.4 0.63 k 21 101 Performance Results Local Node node - with Lambda=0.00005 Local λ = 0.00000 Arrival Time (ms) 400000 400000 200000 200000 0 0 1 5001 10001 15001 20001 25001 30001 1 5001 10001 15001 Message number 20001 25001 30001 Message number Traffic arrival at MN marked Traffic Arrival atwith MN handoff with handoff Al-QudsNode node -with Lambda=0.00005 Al-Quds λ = 0.000005 2000000 Traffic arrival at MNatwith marked Traffic Arrival MNhandoff with handoff Al-Quds Node node - with Lambda=0.00001 Al-Quds λ = 0.000001 2000000 IPMN IPMN Handoff MIP MIP Handoff 1000000 1000000 Arrival time (ms) 1500000 IPMN IPMN Handoff MIP MIP Handoff 1500000 500000 500000 Arrival Time (ms) 5 IPMN IPMN Handoff MIP MIP Handoff 600000 IPMN IPMN Handoff MIP MIP Handoff 600000 Arrival Time (ms) Traffic arrival at MNat with handoff marked Traffic Arrival MN with handoff 800000 800000 TrafficArrival Arrival At with Handoff Traffic atMN MN with handoff LocalNode node -with Lambda=0.00001 Local λ = 0.000001 0 0 1 2001 4001 6001 Message number 8001 10001 1 Figure-7. Traffic arrival at the MN at the two nodes for two values of λ t h e f r a g m e n t n u m b e r . H o f a e n a d c o h 2001 f p f o l o c t c . u r r e n c e 4001 6001 Message number s a t b o t h M I P a n d I P M N 8001 a r e m a r k e 10001 d o n AGENDA • • • • • • • • Problem Statement Related Work Network Layer Solutions Proposed Scheme Performance Analysis Modeling 3-Layer Handoff Performance Analysis Conclusion 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. 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. 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 tware overheads... L2 handoff model for 802.11 • Link Layer Latency – Probing S d u * Tu e * Te Tu 2 * Td MaxChannelTime Te 2 * Td MinChannelTime S d u * (2 * f t (t )dt MaxChannelTim e) e * (2 * f t (t )dt MinChannelTim e) 0 0 – Authentication Ad f t (t )dt PTa i 1 0 n Where 1 n u – Association/Re-Association RAd 2 * f t (t )dt PTr 0 L2 Handoff model for 802.11 • Link Layer Latency – Probing (Scan delay) S d u * Tu e * Te 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 Tu 2 * Td MaxChannelTime Te 2 * Td MinChannelTime Td : Time For probe transmission Td f t (t ) dt 0 ft (t) : characteristic of the channel as a factor of time BER … Transmission rate … L2 Handoff model for 802.11 • Probing Delay – Total Probing delay 0 0 S d u * (2 * f t (t )dt MaxChannelTim e) e * (2 * f t (t )dt MinChannelTim e) – 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. L2 Handoff model for 802.11 • Authentication – Each successfully scanned channel is tried for authentication until a channel is authenticated. n Ad 2 * Td PTa Where 1 n u i 1 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 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. RAd 2 * Td PTr Td : Time For transmission PTr: Time for state information exchange between Access Points after successful Authentication of that channel 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 Table 8: Events for IPMN Layer Link Layer Events Successful Probing Successful Authentication IP Layer IP address change TCP Layer Recv TCP_OPTION=SWITCHIP Ack for TCP_OPTION=SWITCHIP Modeling IPMN • Higher Layer Latency signaling overhead Tg d Ys where 5 Y 20 Event Handler overhead Sycd Xs where 10 X 100 Attaining IP Address PRd 2 * T1d PRd: proactive registration delay for getting an IP address. 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. Modeling 3-layer IPMN MN CH AP TCP LL AP TCP LL ACK Relay IP (a) Overlapping Cell Boundary new AP AP LL Modeling 3-layer IPMN MN CH AP TCP LL AP TCP LL ACK Relay IP (b) Non-Overlapping Cell Boundary new AP AP LL Modeling IPMN • Total IPMN Handoff Delay for overlapping boundary conditions T0 Sd Tgd maxAd , Sycd 2 * Tgd maxRAd , 3 * Sycd PRd Epd Sycd • Total IPMN Handoff Delay for non-overlapping boundary conditions Tn0 Sd Tgd maxAd , Sycd 2 * Tgd RAd , 4 * Sycd PRd Epd Sycd Modeling MIP • MIP Handoff consists – Movement Detection M d x1 2 * Td x2 N d – Registration Rd 2 * Td 2 – Tunneling Tud 2 * ITd • MIP Handoff consists H d Ld M d Rd ITd 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 nonoverlapping 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 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. AGENDA • • • • • • • Problem Statement Related Work Network Layer Solutions Proposed Scheme Performance Analysis Modeling 3 layer IPMN Conclusion 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. 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.