Optimal Service Delivery in Mobile Networks

Transcription

1 Optimal Service Delivery in Mobile Networks Ashutosh Dutta, Ph.D. Senior Scientist NIKSUN Princeton, NJ, USA WWSMC 11, NJ USA, July

2 A name identifies what you want, An address identifies where it is, and An route identifies a way to get there John Shoch, 1978

3 Talk Outline Evolution of Mobile Networks Service Delivery in Mobile Networks A taxonomy of IP mobility Handoff optimization Use case scenarios Measurement-based mobility model Conclusions. 3

4 Evolution of mobility protocols 1 G 2 G 2.5 G 3 G 4 G IEEE TACS 80 Mb/s (UL), 360 Mb/s GSM GPRS EDGE NMT 9.6 kb/s 54 kb/s 236 kb/s JTACS NTT PDC 42 kb/s WCDMA 144 kb/s, 384 kb/s, 2 Mb/s 80 Mb/s EHSPA IS Mb/s (DL), 22 Mb/s (UL) AMPS SMR 48.6 kb/s IS-95 (A) 9.6 kb/s iden 24 kb/s IS-95 (B) 115 kb/s CDMA2000 1X 144 kb/s CDMA2000 NX 144 kb/s, 384 kb/s, 2 Mb/s UMB 280 Mb/s LTE 50 UL, 100 DL

5 Mobile Wireless Internet: A Scenario Domain1 WAN Internet Domain2 PSTN gateway UMTS/ CDMA Bluetooth a/b/g WAN a/b/g IPv6 Network PAN LAN LAN Hotspot PSTN Roaming User CH UMTS/CDMA Network Ad Hoc Network

6 Service Delivery Metrics QoE => Perceived Quality of Service Network Metrics Bit rate, delay, jitter, packet loss rate Power consumption Application Metrics Call setup delay Failed calls, dropped calls, retransmission MOS (Mean Opinion Score) for media Several standards groups ITU-T SG12 ITU X.902 (IP Telephony) IETF IPPM, DIFFSERV 3GPP 3GPP TS (IMS performance) Slide 6

7 Mobility Taxonomy IP Mobility Personal Terminal Service Session Issues Mobility pattern NetworkTransport Layer Layer MIPv4 Cellular IP HAWAII IDMP MIP-LR MIPV6 ProxyMIPv6 MSOCKS, Migrate msctp Shim Layer HIP Application Layer SIPMM MIP-LR(M) Proxy Systems Optimization Host controlled vs. Network Controlled

8 Use Case: Cross layer and multiple interfaces Zone 1 Zone 2 Zone 3 Ne tw or k Ty pe GS M d S SI D/ C ell ID Connect to WLAN N A B S SI D N/ A N A Op er at or AT &T T- Mo bile Se cu rit y N W C ha nn el NA NA 1 9 PK M EAP- PEA P Q o S N / A Y e s Ph ysi cal La yer Dat a Rat e N/A 9.6 kbps OF DM 40 Mbp s Wakeup WLAN Download over WLAN Shutdown GPS Wi-Fi Wi-Fi Zone 4 Zone 5 Zone 6 Airport WLAN Link Going Down. Radio State Café GSM Shutdown GPS Start Download over WLAN Switch to WiMAX Download over WiMAX Shutdown WLAN Wakeup GPS Wakeup WLAN Battery level low Shutdown WiMAX Download over GSM/GPRS Zone 7 Wi-MAX Zone 8 Wi-MAX Zone 9 Network Type SSID/ Cell ID BSSID Operator Security NW EAP Channel QoS Physical Type Layer Data Rate GSM N/A AT&T NA NA 1900 N/A N/A 9.6 Kbps kbps b Airport Café 00:00: Airport Café.11i EAP- PEAP Courtesy: IEEE WLAN WiMAX GPS 6.11e OFDM 11 Mbps

9 Mobility Illustration in a sample IP-based network Administrative Domain B Registration Agent Authorization Agent Authorization Agent Administrative Domain A Registration Agent Signaling Proxy L2 PoA L2 PoA Authentication Agent Configuration Agent L3 PoA D L3 PoA N1 N2 Backbone Configuration Agent N1- Network 1 (802.11) N2- Network 2 ( CDMA/GPRS) Authentication Agent Layer 3 PoA N2 N1 C Signaling Proxy L3 PoA B A Layer 2 PoA IP ch Corresponding Host Layer 2 PoA Mobile Host Handoff Delay CDMA ~ 18 s ms media interruption h/o delay 900 ms h/o delay 18 s 18 Seconds media interruption 4 Seconds media interruption h/o delay 4 s 9

10 System decomposition of handover process Handover Event P1 P2 P3 P4 P5 P6 Network discovery & selection Network attachment Configuration Security association Binding update Media reroute P11 Channel discovery P13 Server discovery P12 Subnet discovery P21 L2 associatio n Domain Advertisement P22 P23 Router solicitation P31 Identifier acquisition P32 P33 Duplicate Address Detection Address Resolution P41 Authentication (L2 and L3) P42 Key derivation P51 P52 Identifier update Identifier Verification P53 Identifier mapping Binding cache Tunneling P54 P61 P63 Buffering P62 Forwarding P64 Bi-casting/ Multicasting 10

11 How security affect handoff performance Security protocols have an impact on the performances of the network End-to-end latency Throughput Handoff delay Packet loss Main components that affect the performance Authentication/authorization, Key Derivation Encryption Security related delays may affect all the layers Layer 2 (e.g., i, WEP) Layer 3 (IPSEC/IKE) Upper Layers (e.g., TLS, SRTP) Server Layer 4 Layer 3 Security Association Layer 2 Key Distribution Authentication Encryption Mobile MN Server MN Network L3 POA

12 Key principles for security optimization Number of round trip signaling for key derivation process need to be minimized Avoid the key exchange by maintaining the end-point address identifier (e.g., IP address) Avoid tear down and re-establishment of Security Association (e.g., IPSec Tunnel) Proactive authentication Fast re-authentication Security context transfer between the base stations Cross layer assisted authentication Layer 3 authentication bootstraps layer 2 authentication process Anchor-based security association Clients behind Mobile IP Home Agent are shielded from IP address change

13 Media Independent Pre-authentication - a deployment scenario AR Network 4 Information Server INTERNET CN Network 3 Current Network 1 AR AP1 TN AA Network 2 MN-CA key CA AP2 AR AR CTN MN-CA key AA CA AP3 AP1 Coverage Area Mobile AP 2 & 3 Coverage Area CTN Candidate Target Networks TN Target Network

14 Network-Layer Assisted Pre-Authentication Supports handover across intertechnology, inter-subnet and inter-domain Radius/Diameter Home AAA Domain AAAh Independent of link-layer technology (e.g., , CDMA) No context transfer security problems (e.g. no domino effect) Roaming AAA Domain* nar/paa PSK Network A PSK Association & 4-way handshake AP2 AAAv PANA pre-auth AP /24 par / /24 AP0 Network B MN IEEE i Pre-authentication PANA Pre-authentication

15 Network Pre-authentication Flows PaC Network-Layer Pre-authentication PaC s Movement Pre-configuration PSKx 4-way hanshake current APx target APx target PAA AAAv AAAH Associated PANA-Client-Initiation(PCI) PANA-Start-Request (PSR) [EAP Req/Ident] PANA-Start-Answer(PSA) [EAP Resp/Ident] PANA-Auth-Request (PAR) [EAP-TLS/Start] PANA-Auth-Answer (PAN) [EAP-TLS/Client-Hello] PANA-Auth-Request (PAR) [EAP-TLS/ServCert] PANA-Auth-Answer (PAN) [EAP-TLS/ClientCert] PANA-Auth-Request (PAR) [EAP-TLS/ChangeSpec] PANA-Auth-Answer (PAN) [EAP-TLS/Ack] PANA-Binding-Request[AUTH] (PBR) (EAP-Success) PANA-Binding-Answer (PBA) Non-roaming Roaming AAA prot-req (EAP-Resp/Ident) AAA prot-ans (EAP-TLS/Start) AAA prot-req (EAP-TLS/Client-Hello) AAA prot-ans (EAP-TLS/ServCert) AAA prot-req (EAP-TLS/ClientCert) AAA prot-ans (EAP-TLS/ChangeSpec) AAA prot-req (EAP-TLS/Ack) AAA prot-ans (EAP-Success) SNMPv3-Set(PSK, PaC s MAC address) SNMPv3-Ack PSK (Re)Association PSKx installation EAP skipped EAPOL Key: Message 1 EAPOL Key: Message 2 EAPOL Key: Message 3 EAPOL Key: Message 4 1x controlled port enabled & IP traffic

16 Performance (MPA-Non-MPA) Single I/F MPA No packet loss during pre-authentication, pre-configuration and pro-active handoff before L2 handoff Only 0 packet loss, 4 ms delay during handoff mostly transient data Includes delay due to layer 2, update to delete the tunnel on the router We also reduced the layer 2 delay in hostap Driver L2 delay depends upon driver and chipset MPA Approach handoff 4 s non-mpa About 200 packets loss, ~ 4 s during handover Includes standard delay due to layer 2, IP address acquisition, Re-Invite, Authentication/Authorization Could be more if we have firewalls also set up Non-MPA Approach

17 Optimized handoff delay with MPA (Multiple I/F) Handoff Delay CDMA ~ 18 s a. MIP-based Non-optimized handoff CDMA Handoff Delay CDMA 16 s c. MPA and assisted optimized handoff b. SIP-based Non-optimized handoff

18 Triple Encapsulation for Mobile VPN Internal (protected) External (unprotected) CN i-ha i-mip tunnel VPN GW VPN tunnel x-ha x-mip tunnel External Network 1 External Network N Internal Home Network Internal Visited Network DMZ MN MN MN MN Based on its current location, MN dynamically establishes/changes/terminates tunnels without changing current standards of IPsec VPN or Mobile IP. Triple encapsulation tunnel is constructed by: i-ha (Internal Home Agent): Forwards IP packets to MN s current internal location VPN GW: Protects (encrypts and authenticates) IP packets transmitted in external networks x-ha (External Home Agent): Forwards IP packets to MN s current external location

19 RTP S equence RTP S equence RTP Packet Sequence Results: Mobile IP-VPN Non-M a ke -be fore -bre a k RTP S equenc e Cellular Secured Handoff RTP sequence during handoff Non -m ake -b efore -break (e nterpris e) Cellular Packet Loss Due to Non -make-before -break (en te rprise ) Tim e in S e conds Cellular (enterprise) (enterprise) Out-of-order-packet Time in Seconds Hand-off with no-make-before break (internal-external-internal) with make-before-break CN VPN GW MN VPN traffic in VPN traffic in cellular Hom e-cellular-hots pot handoff RTP S equenc e Cellular External Hotspot Home T im e in S e co n d s RTP Tunnel (RTP) MOBIKE MOBIKE MOBIKE MOBIKE Visited Network 1 (Cellular) Mobike in cellular Mobike in IP0 address of interface IP1 address of cellular interface IP0 is primary address Visited Network ( is up) (802.11) (First packet on ) IP1 is primary address (Last packet on cellular) (Last packet on ) IP0 is primary address Packet Visited Network Loss (Cellular) (No-Break-before-make) Home-external-external handoff Mobike-based handoff (cellular-hotspot-cellular)

20 Handoff Optimization in IMS/MMD Network AAA/HSS Optimization HSS non-sip AS AAA HA S-CSCF SIP AS Non-SIP support non SIP IMS/ MMD I-CSCF E-CSCF Different Domain cdma2000 PCRF DHCP PDSN RAN P-CSCF IPSec Tunnel cdma200 0 PCRF DHCP PDSN RAN P-CSCF IPSec Tunnel FTTH /ADSL AP PCRF DHCP P-CSCF Optimized roaming architecture MN MN P-CSCF Fast handoff 20

21 Types of Handoff P-CSCF Fast-handoff Experimental Results Components Optimized PPP Termination Non-Optimized Layer 2 Delay Reactive Proactive PPP Activation MIP-Solicitation MIP-Binding Update DHCP Trigger DHCP Inform SIP Trigger SIP+Security Media Redirection Time in ms Components Optimized Figure 1: Levels of MMD Optimization 21

22 Optimal mobility system design Scheduling of handover operations Relevant optimization principles SIP-based Fast handoff Mobile VPN Example experimental mobility optimization Media Independent Pre-authentication Simultaneous Mobility Optimized handoff In IMS Muti-layer Mobility Multicast fast handoff Potential Target Mobility System Sequential Direct path between CH and MH Limit binding update between CH and MH X X X Maintain Security association between end-points X Anchor-based Forwarding X X Post-handoff triggers X Proactive Pre-handoff triggers X X Proactive network discovery X Proactive authentication X Proactive identifier configuration X Proactive binding update X X Dynamic Buffering X Proactive context transfer X Parallel Discovery of Layer 2 and Layer 3 PoA X 22

23 Measurement assisted mobility model DNS/E NUM P-CSCF S-CSCF HSS S-CSCF Invite OK ACK RTP diameter GETS- Application Server I-CSCF P-CSCF SIP DNS Monitoring Agent PCRF IMS PCRF Layer 3 control Network/ Application Feedback IMS-layer control Layer 2 control Controller Managed IP (Multi-Provider Network) (EPC) GW GETS Call Wireline Access Cable DSL Fiber Ethernet Caller (UE1) GW RAN IP CAN Wireless Access UMTS EvDO WiMAX LTE Satellite 23 RAN Wireless Access UMTS EvDO WiMAX LTE Satellite RAN RAN IP CAN Called (UE2) Wireline Access Cable DSL Fiber Ethernet 23

24 Resource usage per mobility events Sub transitions Sub-operations Resource Consumption Bytes exchanged CPU samples Power due to transmission (nano joules) t00 Layer 2 un-reachability test t01 Layer 3 unreachability t11 Discover layer 2 channel t12 Discover layer 3 subnet t13 Discover server t21 Layer 2 association t22 Router solicitation t23 Domain advertisement t31 Identifier acquisition t32 Duplicate address detection t33 Address resolution t41 Layer 2 open authentication t42 Layer 2 EAP t43 Four-way handshake t51 Master key derivation (PMK) t52 Session key derivation (PTK) t61 Identifier update t62 Identifier verification t63 Identifier mapping t64 Binding cache t71 Fast binding update t72 Local caching t81 Tunneling t82 Forwarding t83 Buffering t91 Local id mapping t92 Multicasting/bicasting

25 Modeling of handoff processes An example p31 p32 p33 Resource network capacity Potential Parallel Operation t31 t32 t33 t64 p64 t70 p11 p21 p22 p12 p23 P52 t53 p53 p61 Connected t11 t21 t22 t12 t23 t52 t51 P51 t54 p54 P00 t01 p41 p42 p62 p63 t13 Resource Battery t41 t42 p13 t62 t63 Resource CPU

26 Scheduling of handoff operations P A Network capacity Resources Network capacity P A 1 token 2 2 Mobile Disconnected Connected Network Discovered Mobile authenticated P1 P2 P3 P4 t2 t3 t4 t5 P 0 t1 scanning Authentication 4-way Handshake Association Disconnection Connected P0 t1 P01 Scanning P02 t2 t3 P1 Network Discovered Mobile Authenticated P2 t4 Association P3 4-way handshake complete t5 CPU cycles P C P B Battery power Authentication Resources CPU P C 4-way Handshake Operation Resource s Battery P B Current Network A. Sequential operations Target Network B. Parallel operations Level of concurrency =2 Resources P A Network Capacity P A 1 P11 PB1 Network discovery t11 t13 P12 t12 Preauthentication AP Key installation P1 Connected t1 P D Dis connected P2 4-way Handshake (SA) C. Proactive operations t4 P A 2 P3 P C Association t5 Connected P0 t1 P03 P01 Authentication P02 4-way Handshake Scanning t2 t3 t4 2 P1 P2 P3 Network Discovered P C CPU Mobile Authenticated D. Parallel operations Level of concurrency = 3 Battery PB t5 4 Association 26

27 Conclusions IP-based mobility in 4G networks involves movement across access technologies, movement across administrative domains, at multiple layers and involve interaction among multiple protocols Measurement-based Mobility model Allows to predict the handoff performance Provides trade-off performance (e.g., Resources vs. QoS) Allows to study behavioral characteristics deadlock based on mobility patterns Best current practices to provide optimal service delivery under different mobility pattern under different resource environment For different applications Mobile Cloud Computing, Real-time, Non-real-time 27

28 Burlingame, CA USA June

29 Cellular mobility GSM AUC HLR VLR EIR BSS MSC BSC 1 BSC 2 BTS A opoa BTS B npoa npoa BTS C npoa BTS D Serving Cell MH Move Target Cell

30 SAE/LTE (4G) S10 Enhanced Packet Core (EPC) SGSN Source enb S4 S1-MME X2 S3 Target enb X2 MME Serving Gateway (S-GW) S1-U E-UTRAN Candidate enb UE UE UE X2 S11 S5 S8 S6a PDN-GW Trusted Non-3GPP (WiFI, WiMAX) UTRAN IP-based IMS network Slide 30 NIKSUN Confidential Restricted Access See Title Page for Restrictions S2a HSS S7 SGi UE PCRF S2b epdg S6c Wn Wm Untrusted Non-3GPP Rx+ Wx AAA UE

31 QoE metrics Driven by measurements Slide 31

32 Optimizing authentication Related Work IEEE Standards IEEE i provides pre-authentication at link-layer in the distribution system (DS) IEEE r improves 11i by introducing a new key hierarchy but it does not work between DSs either. Context transfer solutions (Bargh et al, Georgiades et al, Duong et al) Security problems such as domino effect Assume certain trust relationships which might not be possible in certain scenarios. Oriented towards the same technology Re-authentication Pre-installation based on movement pattern (Mishra et al, Pack et al ) AAA assisted key installation Works within the same administrative domain MIPv6 and AAA assisted (Ruckforth et al) Limited to MIPv6 and within the same domain Cooperative Roaming (Forte et al) Works within a domain

33 Key principles for SA optimization Avoid the key exchange by maintaining the endpoint address identifier Avoid tear down and re-establishment of Security Association Reduce the number of signaling messages that help rekeying Anchor-based security association Clients behind NAT are shielded from IP address change

34 802.11i Pre-authentication Flow STA Current AP Target AP AAAv AAAH IEEE 11i Pre-Authentication PMKsta-targetAP Associated EAPOL Start EAPOL-Request(EAP-Req/ident) EAPOL-Response(EAP-Resp/ident) EAPOL-Request(EAP-TLS/Start) EAPOL-Response(EAP-TLS/Client-Hello) EAPOL-Request(EAP-TLS/ServCert) EAPOL-Response(EAP-TLS/ClientCert) EAPOL-Request(EAP-TLS/ChangeSpec) EAPOL-Response(EAP-TLS/Ack) EAPOL-Request(EAP-TLS/Sucess) Non-roaming Roaming AAA prot-req (EAP-Resp/Ident) AAA prot-ans (EAP-TLS/Start) AAA prot-req (EAP-TLS/Client-Hello) AAA prot-ans (EAP-TLS/ServCert) AAA prot-req (EAP-TLS/ClientCert) AAA prot-ans (EAP-TLS/ChangeSpec) AAA prot-req (EAP-TLS/Ack) AAA prot-ans (EAP-Success) PMKsta-targetAP 4-way hanshake (Re)Association EAPOL Key: Message 1 EAPOL Key: Message 2 EAPOL Key: Message 3 EAPOL Key: Message 4 1x controlled port enabled & IP traffic

35 Key Derivation Process Post-auth AAA Authentication Server i Pre-auth AAA Network-Layer Preauth AAA Authentication Server MSK Authenticator AP MSK PMK 4-way handshake (PTKs) AP MSK Authenticator AP MSK PMK AP MSK PAA AP PSKap MSK PaC-EP-Master-Key PSK PSKap PMK 4-way handshake (PTKs) MN MSK PMK WPA Supplicant MN 4-way handshake (PTKs) MN MSK MSK PMK PaC-EP-Master-Key PSK PMK WPA Supplicant

36 Technical issues for mobility management Key Functions Handoff Characteristics May take place between cell, subnet or domain Need to optimize the handoff delay and transient data loss ( e.g., end-todelay up to 200 ms, 3%-5% packet loss, jitter, for real-time VoIP traffic) May use soft-handoff feature of CDMA, but need fast-handoff mechanisms for other technologies (e.g., ) Need to support session based applications for TCP and RTP traffic Configuration Registration Should be configured within few milliseconds Configures IP address and other server parameters (e.g, DNS, SIP server, Gateway) Assist pre-session mobility Hierarchical nature will make the registration faster Helps location management functionality Quality of Service Location Management Need to maintain same QoS during its subnet/domain movement Allow user to maintain same URI irrespective of point of attachment

37 Mobility model Problem: In the absence of any formal mechanism it is difficult to predict or verify the systems performance of un-optimized handover or any specific handoff optimization technique Proposal Analyze the basic primitives of a handoff event Model the handoff-related processes as Discrete Event Dynamic Systems (DEDS) Deterministic Timed Transition Petri Net (DTTPN) to build various unoptimized mobility models and their associated optimization techniques Key advantages : This model can predict systems performance for optimized handoff operations This model can design optimal path for sequence of execution of events based on expected performance and resource constraints This model can verify systems behavior (e.g., deadlocks) during handover 37

38 Dependency analysis among handover operations Handoff Process Precedence Data it depends on Relationship P 11 Channel Discovery P 00 Signal-to-Noise Ratio value P 12 Subnet discovery P 21,P 22 Layer 2 beacon ID L3 router advertisement P 13 Server discovery P 12 Subnet address Default router address P 21 - Layer 2 association P 11 Channel number MAC address Authentication key P 22 - Router solicitation P 21, P 12 Layer 2 binding P 23 - Domain advertisement P 13 Server configuration Router advertisement P 31 Identifier acquisition P 23,P 12 Default gateway Subnet address Server address P 32 Duplicate address detection P 31 ARP Router advertisement P 33 Address resolution P 32, P 31 New identifier P 41 Authentication P 13 Address of authenticator P 42 Key Derivation P 41 PMK (Pairwise Master Key) P 51 Identifier update P 31,P 52 L3 Address Uniqueness of L3 address P 52 Identifier verification P 31 Completion of COTI P 53 Identifier mapping P 51 Updated MN address at CN and HA P 54 Binding cache P 53 New Care-of-address mapping P 61 Tunneling P 51 Tunnel end-point address Identifier address P 62 Forwarding P 51, P 53 New address of the mobile P 63 Buffering P 62, P 51 New identifier acquisition P 64 Multicasting/Bicasting P 51 New identifier acquisition 38

39 Backup Slides Burlingame, CA USA June

40 Characteristics of Next Generation Networks? Heterogeneous networks (CDMA, LTE, WiMAX, ) Access-independent converged IP network Order-of-magnitude increases in bandwidth MIMO, smart antennas Increase in video and other high bandwidth traffic New services and service enabling platforms (e.g., Web 2.0, SON) Large range of cell sizes, coverage areas PAN, LAN, WAN Pico-cellular, micro-cellular, cellular Changes in traffic and traffic patterns Rise in video on demand? Requires good high-bandwidth multicast

41 Results (II)

42 Cellular Access Characteristics Generation System Channel spacing Access type Uplink data rate 1G AMPS 30 khz FDMA N/A TACS 25 khz FDMA N/A NMT 25 khz FDMA N/A NTT 25 khz FDMA N/A 2G GSM 200 khz TDMA 9.6 kb/s PDC 30 khz TDMA 42 kb/s IS khz F/TDMA 48 kb/s IS-95 (A) 1.25 MHz F/CDMA 14.4 kb/s iden 25 khz F/TDMA 24 kb/s 2.5G GPRS 200 khz TDMA 45 kb/s EDGE 200 khz TDMA 236 kb/s IS-95 (B) 1.25 MHz F/CDMA 115 kb/s CDMA2000 1X 1.25 MHz CDMA 144 kb/s 3G UMTS/WCDM 5 MHz CDMA/TD 2 Mb/s A MA CDMA MHz CDMA 2 Mb/s 1xEV-DO 4G LTE 20 MHz OFDMA 50 Mb/s WiMAX 2.5 GHz OFDM 40 Mb/s UMB 5 MHz OFDMA 75 Mb/s

43 Handover: Distributed operation across multiple layers CN Discovery Detection Configuration Security Association p42 Binding Update p52 p54 Media Rerouting p61 Server (Proxy, /HA) p13 p23 p31 p32 p41 p42 p52 p51 p53 p54 p61 p63p64 p62 L3 PoA p12 p22 p31 p32 p33 p42 p51 p61 p62 L2 PoA p11 p21 p31 p41 p42 p51 p11 p12 p13 p21 p22 p23 p31 p32 p33 p41 p42 p51 p52 p61 MN Time

44 De-authentication Delay Layer 2 Handoff Delay (802.11) Station performing handoff Probe Delay MN Authentication Delay Re-association Delay (broadcast) Probe Request Probe Response Reassociation Request De-authentication Authentication Request Authentication Response Re-association Request Re-association Request Re-association Response All APs within range on all channels Chan 1 Chan N New AP Discovery Phase Active scanning MN probes AP Passive scanning AP sends beacons periodically Authentication Phase Open authentication Shared authentication i 4 way handshake Association Phase

45 Layer 2 Discovery Optimization General techniques: Reduce the scanning time Caching of ESSID Use of second interface specific discovery Proactive Discovery (no scanning) Proposed Solutions: Shin et al introduces selective scanning and caching strategy Montavont et al propose periodic scanning Velayos et al propose reduction of beacon interval and performs search in parallel with data transmission Brik et al propose to use a second interface to scan while communicating with the first interface u, k Forte and Schulzrinne Application Layer proactive discovery (e.g., Dutta et al)

46 Optimization techniques for layer 3 configuration Layer 3 address acquisition Proactive caching Duplicate Address Detection Optimistic DAD, Proactive DAD, Passive DAD, Router Assisted DAD NUD (Neighbor Unreachability Detection) Aggressive Router Selection Mobile Node Identifier Acquisition L3 PoA Server Layer 3 Configuration Layer 2 Duplicate Identifier Address Mapping Verification Network Server MN Mobile Node L3 POA Network

47 Security Optimization Security protocols have an impact on the performances of the network End-to-end latency Throughput Handoff delay Main components that affect the performance Authentication/authorization, Key Derivation, Encryption Security related delays may affect all the layers Layer 2 (e.g., i, WEP) Layer 3 (IPSEC/IKE) Upper Layers (e.g., TLS, SRTP) Server Layer 4 Layer 3 Security Association Layer 2 Key Distribution Authentication Encryption Mobile MN Server MN Network L3 POA

48 Optimizing Binding Update Techniques Reduce the latency due to longer binding update when the communicating host is far away Limit the binding update within a domain Proposed Solutions IDMP Regional registration-based Mobile IP HMIPv6 Anchor-based Application Layer B2BUA Proactive Binding Update Binding Update Tunneling Mapping Caching Anchor Point CN Mobile Network Anchor Mobile CN

49 PSTN CDMA2000 An example Home Agent FA1 FA2 GMSC PDSN1 L3 PoA PDSN2 L3 PoA AC HLR VLR PCF1 PCF3 PCF4 PCF2 MSC BSC1 BSC2 BSC3 BSC4 BTS1 L2 PoA BTS3 L2 PoA A B C D E F

50 Optimized handoff delay with MPA (Multiple I/F) Handoff Delay CDMA ~ 18 s a. MIP-based Non-optimized handoff CDMA Handoff Delay CDMA 16 s c. MPA and assisted optimized handoff b. SIP-based Non-optimized handoff

51 Several concepts of mobility Terminal mobility, e.g., supported by Mobile IP CH Subnet 1 IP-based Network Subnet 2 MH Typically, you don t just have terminals CH IP-based Network Subnet 2 Users/Persons Subnet 1 Sessions Mobility of users, sessions? MH

52 Personal Mobility: Registration registrar CH IP-based Network Subnet 2 Subnet 1 person@subnet2.org registrar When lady in red moves, she leaves her laptop behind CH IP-based Network Subnet 2 Uses another machine Logs in Subnet 1 User registration performed

53 Personal Mobility: simultaneous registration of multiple bindings CH Subnet 1 Registrar & proxy IP-based Network When lady in red moves, she leaves her laptop behind Uses another machine She can still be located person@subnet1.org person@subnet2.org Subnet 2 CH Subnet 1 person@subnet1.org person@subnet2.org Registrar & proxy IP-based Network Subnet 2

54 Session Mobility INVITE 2 3 CH IP-based Network Subnet 2 1 Subnet 1 MH CH IP-based Network Subnet 2 Subnet 1

55 Mobike-based solution

56 Service Mobility Service Mobility allows a roaming user to get the same view of the network as when he is at home At the time of registration User s service profile is retrieved from the home network The service profile is shared with the responsible entity at home and in the foreign network (wholly or partially) The foreign network provides some of the service required The home network still retains responsibility for other services Examples of entries in the profile of interest may be address book, call handling features, buddy lists, etc.