Wireless Networks III: advanced concepts. Hans-Peter Schwefel and Tatiana K. Madsen. Mm3 Wireless applications, SIP & IMS (HPS)

Transcription

1 Wireless Networks III: advanced concepts Hans-Peter Schwefel and Tatiana K. Madsen Mm1 IP Mobility Support (HPS) Mm2 Wireless TCP (HPS) Mm3 Wireless applications, SIP & IMS (HPS) Mm4 Ad-hoc Networks I (TKM) Mm5 Ad-hoc Networks II (TKM) hps@kom.auc.dk Note: Slide-set contains more material than covered in the lecture! tatiana@kom.auc.dk Page 1 Intro: Cellular systems Geographic region subdivided in radio cells Base Station provides radio connectivity to Mobile Station within cell Handover to neighbouring base station when necessary Base Stations connected by some networking infrastructure Page 2

2 Extended layered communication model Ultimate goal of (wireless) service provisioning: user satisfaction Focus in this course: network aspects, i.e. Layers 2-5 Functionalities, that are difficult to assign to single layers: Mobility support Quality of service support Security (authentication, etc.) Dependability/Resilience... More later in this session/course [see also WNII] User User Interface Application Middleware (L5) Session Control, e.g. SIP L4: Transport: TCP, UDP, RTP/UDP L3: Network Layer: IP L2: MAC/LLC L1: PHYS User Environment Network QoS Application QoS User perceived QoS Page 3 Content 1. Background Mobility & Handover Types 2. Link-Layer Hand-over Example: WLAN Network Layer Mobility Support: MIP Motivation, Principles, Messages Performance Enhancements: HMIP MIPv6 4. Higher-Layer Mobility Support Goal: Make students familiar with underlying problems solution approaches Overview on key technologies required to support mobility in IPbased networks Transport Layer Mobility, e.g. mobile SCTP Session-Layer: SIP Host Identity Protocol, HIP 5. Hand-over extensions Multi-homing & flow mobility Context transfer Cross-layer aspects 6. Summary & Outlook Appendix: Experimental Measurements Page 4

3 Background II: Mobility types WLAN AP Switch Router Router Mobile Host WLAN AP Router WLAN AP WLAN AP Router D Router Cellular access (GPRS) Internet GPRS Network Assumption in this lecture: Infrastructure networks (only first hop wireless) Different Levels of Mobility: Pico (e.g. within same radio cell) Micro (e.g. within same subnet) Macro (e.g. across subnets but within same administrative domain) Global (e.g. across different administrative domains) Alternative classification: vertical mobility: changing access technology Page 5 Background III: Handover & more mobility types Hand-over classification: Mobile initiated or network-initiated Backward or forward mobile controlled or network controlled Mobile-assisted or network assisted or unassisted Proactive or reactive Make-before-break or break-before make Soft or hard fast (without noticable delay) seamless = fast + smooth smooth (no loss of data) More mobility types... Host Mobility User Mobility Application Mobility Network Mobility... and related identifiers IP address, hostname (DNS) User-name (e.g. SIP URL) --- address prefix / subnetmask Page 6

4 Content 1. Background Mobility & Handover Types 2. Link-Layer Hand-over Example: WLAN Network Layer Mobility Support: MIP Motivation, Principles, Messages Performance Enhancements: HMIP MIPv6 4. Higher-Layer Mobility Support Transport Layer Mobility, e.g. mobile SCTP Session-Layer: SIP Host Identity Protocol, HIP 5. Hand-over extensions Multi-homing & flow mobility Context transfer Cross-layer aspects 6. Summary & Outlook Appendix: Experimental Measurements Page 7 Link-Layer Hand-over: Measurements b Scenario Hard Handover in b Both APs use same SSID HO initiated by pulling cable from AP1 ( Istanbul ) Source: Master Thesis, Rui Martins Page 8

5 Measurements II: Hard Hand-over Page 9 Measurements III: Soft Hand-over Scenario Page 10

6 Measurements IV: Soft Handover Results Page 11 Content 1. Background Mobility & Handover Types 2. Link-Layer Hand-over Example: WLAN Network Layer Mobility Support: MIP Motivation, Principles, Messages Performance Enhancements: HMIP MIPv6 4. Higher-Layer Mobility Support Transport Layer Mobility, e.g. mobile SCTP Session-Layer: SIP Host Identity Protocol, HIP 5. Hand-over extensions Multi-homing & flow mobility Context transfer Cross-layer aspects 6. Summary & Outlook Appendix: Experimental Measurements Page 12

7 Mobile IP Motivation: Host mobility & Routing Problem: IP address identifies host as well as topological location Reason: IP Routing: Routes selected based on IP destination address network prefix (e.g ) determines physical subnet change of physical subnet change of IP address to have a topological correct address IP network Subnet A Mobile Node Subnet B Solution? Host-based routing: Specific routes to each host Handover change of all routing table entries in each (!) router Scalability & performance problem Solution? Obtain new IP-address at hand-over Problem: how to identify host after handover? DNS update performance/scalability problem Higher protocol layers (TCP/UDP/application) need to handle changing IP address Development of mobile IP Page 13 Mobile IP: Requirements (RFC 3344) Transparency mobile end-systems keep their IP address point of attachment to the fixed network can be changed continuation of communication after handover possible (transparent to transport layer in mobile node as well as to correspondent node) Compatibility support of the same layer 2 protocols as IP no changes to correspondent nodes and routers required Security authentication of all registration messages Efficiency and scalability only small data volume for additional messages to/from the mobile node (connection typically via a low bandwidth radio link) world-wide support of a large number of mobile nodes (via the whole Internet) Page 14

8 Mobile IP: Principles & Terminology Home network IP network HA Mobile Node Home Address IP 1 Correspondent Node Underlying Approach: separate host identifier and location identifier maintain multiple IP addresses for mobile host Terminology: Mobile Node (MN) with fixed IP address IP 1 (home address) Home Network: subnet that contains IP 1 Home Agent (HA): node in home network, responsible for packet forwarding to MN Visited Network: new subnet after roaming / handover Care-of Address (CoA): temporary IP address within visited network Foreign Agent (FA): node in visited network, responsible for packet forwarding to CoA FA Home Address IP 1 Care of Address: CoA 1 Visited network Page 15 Mobile IP: Tunneling &Triangle Routing FA Home Network CoA 1 Visited Network Mobile Node IP 1, CoA 1 Home Agent Source: Mobile IPv4 illustrated IP 2 IP 1 Subnet CN sends packets to the MN using its Home Address IP 1 HA tunnels them to FA, using CoA 1; FA forwards them to MN MN sends packets back to the CN using IP 2 (without any tunneling) Correspondent Node (CN) IP 2 Home Agent needs to contain mapping of care-of address to home address (location register) Page 16

9 Mobile IP: Tunneling Default encapsulation: IP-within-IP (RFC2003) IP-within-IP encapsulation Other Approaches: Minimal encapsulation (RFC2004) Generic Routing Encapsulation (GRE) (RFC1702) Page 17 Tunneling: IP in IP Encapsulation IP-in-IP-encapsulation (support in MIP mandatory, RFC 2003) tunnel between HA and COA ver. IHL DS (TOS) length IP identification flags fragment offset TTL IP-in-IP IP checksum IP address of HA Care-of address COA ver. IHL DS (TOS) length IP identification flags fragment offset TTL lay. 4 prot. IP checksum IP address of CN IP address of MN TCP/UDP/... payload Drawback of tunneling Possibly long routes between CN and MN (many hops) Increase of data volume increase (additional 20 bytes IP header) possibly fragmentation Page 18

10 Tunneling: Minimal Encapsulation Minimal encapsulation (optional) avoids repetition of identical fields (e.g.ttl, IHL, version, DS/TOS) only applicable for un-fragmented packets (no space left for fragment identification) ver. IHL DS (TOS) length IP identification flags fragment offset TTL min. encap. IP checksum IP address of HA care-of address COA lay. 4 protoc. S reserved IP checksum IP address of MN original sender IP address (if S=1) TCP/UDP/... payload Page 19 Mobile IP: Agent Discovery & Registration [Agent Solicitation] (opt.) HA FA Agent Advertisement Registration Request MN Obtain c/o address Registration Reply Time Mobile Node finds out about FA through Agent Advertisements FAs broadcast Advertisements in periodic intervals Advertisements can be triggered by an Agent Solicitation from the MN Care of Address of the MN is determined, either Dynamically, e.g. using Dynamic Host Configuration Protocol (DHCP) Or: use IP address of FA as CoA MN registers at FA and HA: Registration Request & Reply MN signals COA to the HA via the FA HA acknowledges via FA to MN Registration with old FA simply expires (limited life-time, soft-state) Page 20

11 MIP messages:agent advertisement Procedure: HA and FA periodically broadcast advertisement messages into their subnets MN listens to these messages and detects, if it is in the home or a (new?) foreign network type code checksum #addresses addr. size lifetime router address 1 preference level 1 router address 2 preference level 2 when new foreign network: MN reads a... COA from the advertisement (opt.) type = 16 length sequence number ICMP Router Discovery extension: type = 16 registration lifetime R B H F M G r T reserved R: registration required COA 1 B: busy, no more registrations COA 2 H: home agent F: foreign agent... M: minimal encapsulation G: GRE encapsulation r: =0, ignored (former Van Jacobson compression) T: FA supports reverse tunneling reserved: =0, ignored Page 21 MIP messages: registration request & reply Registration Request (via UDP) S: simultaneous bindings B: broadcast datagrams D: decapsulation by MN M mininal encapsulation G: GRE encapsulation r: =0, ignored T: reverse tunneling requested x: =0, ignored Registration Reply (UDP) Example codes: 68 home agent failed registration successful authentication 0 registration accepted 69 requested Lifetime too long 1 registration accepted, but registration denied by HA simultaneous mobility bindings 129 administratively prohibited unsupported 131 mobile node failed registration denied by FA authentication 65 administratively prohibited 133 registration Identification 66 insufficient resources mismatch 67 mobile node failed 135 too many simultaneous authentication mobility bindings type = 1 S B D MG r T x lifetime home address home agent COA Page 22 identification extensions type = 3 code lifetime home address home agent identification extensions...

12 time MIP: Care-of addresses MN obtains local care-of address either from FA Advertisement (see before) Or via Dynamic Host Configuration Protocol (DHCP) supplies systems with all necessary information, such as IP address, DNS server address, domain name, subnet mask, default router etc. Client/Server-Model: client sends request via L2 broadcast server (not selected) determine the configuration DHCPDISCOVER client initialization DHCPOFFER collection of replies DHCPOFFER selection of configuration DHCPREQUEST (reject) initialization completed DHCPDISCOVER DHCPREQUEST (options) DHCPACK server (selected) determine the configuration confirmation of configuration Page 23 Hierarchical Approaches Optimization for: long registration delay inefficient routing paths Frequent re-registration at HA (even though mostly local mobility Example (Hierarchical Mobile IPv4): Hierarchy of Foreign Agents Every FA re-tunnels the packets to the next FA until it reaches the MN When a handoff occurs, the MN sends a regional registration request to the lowest level FA FAs can also re-direct up-stream packets, if the destination (home-address) is registered within their domain Page 24 Similar Approach using local Home Agents (called Mobility Anchor Points) in HMIPv6 draft-ietf-mobileip-hmipv6-08.txt (June2003)

13 Hybrid Approaches: Cellular IP Solutions to the local management of micromobility events Mobile IP is used for global mobility A gateway (GW) acts as foreign agent for each domain (all MNs use GW address as c/o) Within the domain: host-based routing routing cache entries using soft-state routing cache updated by upstream packets separate paging cache for in-active nodes routers within domain have to be CIP aware Similar approach: Hand-off Aware Wireless Access Internet Infrastructure (HAWAII) data/control packets from MN 1 BS MN1 BS Internet CIP Gateway BS MN2 Mobile IP packets from MN2 to MN 1 Page 25 Hand-over prediction using localization Different methods to obtain device positions Triangulation (signal strength, time of arrival), e.g. GPS Database Correlation Hand-over optimization predict future location based on estimated past trajectory use prediction to start hand-over procedure in advance Problems Accuracy of localization Adequate filtering techniques (see example) Include knowledge of building geometry Include knowledge of mobility patterns Timeliness of location information E.g., Bluetooth localization with several AP 4-10 seconds Page 26

14 MIP Security Aspects I: Basics (optional) General security requirements (Security Architecture for the Internet Protocol, RFC 1825) Authentication the origin of the data can be determined Integrity messages cannot be modified by a third party Confidentiality only authorized partners (e.g. sender & receiver) can read the data Non-Repudiation sender cannot deny sending of data Prevention of Traffic Analysis creation of traffic and user profiles should not be possible Replay Protection replay of earlier messages by an attacker can be detected Additionally: Availability (Prevent Denial of Service Attacks) Page 27 MIP security aspects II: Security associations Security Association (SA) for registrations extended authentication of registration MH-FA authentication FA-HA authentication MH-HA authentication registration request registration request MH FA registration reply HA registration reply (optional) SA contains the following parameters Destination IP address Cryptographic method for encryption/authentication Encryption/authentication key Lifetime of key Specific parameters depending on cryptographic method Page 28

15 MIP security aspects III: Registration (optional) Registration Request Registration Reply Identification field: protection against replay attacks time stamps: 32 bit time-stamp + 32 bit random number Nonces: 32bit random number (MH) + 32 bit random number (HA) Identification Reg. Request Identification Reg. Reply Identification Reg. Reply Identification next Reg. Request Page 29 MIP security aspects IV: Authentication extension (optional) Part of Registration Messages: MN <->HA, MN<->Fa, FA<->HA Computation of Autenticator: cryptographic keyed Hash function (e.g. HMAC-MD5 Algorithm) covering UDP payload All earlier extensions Type, length and SPI of authentication extension Using the shared, secret key SPI (security parameter index) - determines algorithm, mode, and key Page 30

16 MIP security aspects V: Firewall traversal Ingress Filtering Problem: MN sends packets to CN with source address = Home Address (and not c/o address) Firewalls at domain boundaries suspect IP Spoofing discard packets Solution: Reverse Tunneling CH MH Firewall HA Page 31 IP Version 6 (IPv6) IPv6 Basic Header 40 Bytes 128-bit Network Addresses Flow label (QoS) No fragmentation in the network Built-in Security Neighbor Discovery Extension Headers: Routing, Fragmentation, Authentication, Encryption Offset Version Priority Flow Label 4 Payload Length Type of Next Hdr. Hop Limit Source Address Destination Address Next Header Page 32 IPv4 Basic Header 20 Bytes 32-bit Network Addresses Type of Service field Router may fragment packets IPsec as an enhancement ARP (Address Resolution Protocol) Options

17 IPv6 in mobile settings Large number of IP addresses (each device needs at least two addresses!) Stateless autoconfiguration (can replace DHCP) Route Optimisation via binding updates to CN Return Routability Procedure Validate ownership of addresses Exchange Authentication Information Binding update with check of authentication info Soft-state approach: automatic expiry IPv6 Extension Header: Mobility Header (Next Header Value=135) Binding Refresh Request (MH Type=0) Home Test Init (1), Care-of Test Init (2) Home Test (3), Care-of Test (4) Binding Update (5), BU ACK (6), BU Error (7) Page 33 Content 1. Background Mobility & Handover Types 2. Link-Layer Hand-over Example: WLAN Network Layer Mobility Support: MIP Motivation, Principles, Messages Performance Enhancements: HMIP MIPv6 4. Higher-Layer Mobility Support Transport Layer Mobility, e.g. mobile SCTP Session-Layer: SIP Host Identity Protocol, HIP 5. Hand-over extensions Multi-homing & flow mobility Context transfer Cross-layer aspects 6. Summary & Outlook Appendix: Experimental Measurements Page 34

18 Transport Layer Protocols Goal: data transfer between application (processes) in end-systems support of multiplexing/de-multiplexing e.g. socket API data stream/connection identified by: two IP addresses, protocol number, two port numbers Page 35 Overview: Transport Protocols User Datagram Protocol UDP (RFC 768) Connectionless Unreliable No flow/congestion control Transmission Control Protocol TCP (RFC 793, 1122, 1323, 2018, 2581) Connection-oriented (full duplex) Reliable, in-order byte-stream delivery Flow/congestion control Stream Control Transport Protocol SCTP (see later) Real-Time Transport Protocol RTP Uses UDP Provides: Time-stamps, sequence numbers Supports: codecs, codec translation, mixing of multi-media streams Page 36

19 Streaming Control Transmission Protocol (SCTP) Defined in RFC2960 (see also RFC 3257, 3286) Purpose initially: Signalling Transport Features Reliable, full-duplex unicast transport (performs retransmissions) TCP-friendly flow control (+ many other features of TCP) Multi-streaming, in sequence delivery within streams Avoid head of line blocking (performance issue) Multi-homing: hosts with multiple IP addresses, path monitoring (heart-beat mechanism), transparent failover to secondary paths Useful for provisioning of network reliability SCTP Association IPa1 Host A IPa2 Separate Networks IPb1 Host B IPb2 Page 37 Transport Layer Handover in SCTP IP1 AP A 1. MN communicates with CN via established SCTP association (From IP1 to IP CN) 2. When MN comes in Range of AP B MN obtains new IP address IP2 MN adds IP2 to the existing SCTP association Address configuration Change (ASCONF) Chunk 3. When connection should be transferred to new AP B MN sets primary address to IP2 MN deletes old IP1 from SCTP association (ASCONF chunk) IP 2 AP B Correspondent Node Page 38

20 SCTP Mobility support: Discussion SCTP Handover transparent for network No additional network infrastructure needed Possible use-case: switch to peer-to-peer mode without network support avoids tunneling and tri-angular routing Endpoints need to support SCTP (with dynamic control of IP addresses) Signalling to every correspondent node necessary (for every established SCTP association) for high number of parallel connections, large signalling volume over air interface Dynamic Naming Service for connection set-up from CN required (to establish the initial SCTP association) Dynamic DNS Other location mechanisms (e.g. based on SIP URLs) Only usable for traffic without real-time requirements (due to SCTP flow/congestion control) but similar approaches, e.g. for RTP, possible Simultaneous Handover (Mobile Node and Correspondent Node) can lead to loss of connection Page 39 Session Initiation Protocol SIP (more details in MM3) SIP: Application layer signalling protocol (RFC 3261) Provides call control for multi-media services initiation, modification, and termination of sessions terminal-type negotiation and selections call holding, forwarding, forking, transfer media type negotiation (also mid-call changes) using Session Description Protocol (SDP) Properties Independent of transport protocols (TCP, UDP, SCTP, ) ASCII format SIP headers Separation of call signalling and data stream Basic Messages (Methods) INVITE: initiate call ACK: confirm final response (after invite ) BYE: terminate call CANCEL: cancel pending requests OPTIONS: queries features supported by other side REGISTER: register with location service Page 40 Responses 1xx Intermediate results e.g. 180 Ringing 2xx Successful Responses e.g. 200 OK 3xx Redirections e.g. 302 Moved Temporarily

21 SIP Call Signalling: Example Call Setup User Agent INVITE Proxy Server Location/Redirect Server Proxy Server User Agent INVITE 302 (Moved Temporarily) ACK INVITE Media Path Call Teardown 180 (Ringing) 200 (OK) ACK 180 (Ringing) 200 (OK) ACK RTP MEDIA PATH INVITE 180 (Ringing) 200 (OK) ACK BYE BYE BYE 200 (OK) 200 (OK) 200 (OK) Page 41 SIP: Mobility support MN1 User/Session/Application Mobility (change of terminal) Registration via SIP REGISTER Initial connection set-up between MN1 and CN through INVITE mid-session mobility (application mobility): call transfer, SIP method REFER (RFC3515) Application state could be contained in the message body ( proprietary extension) MN2 CN MN1 Host Mobility (change of IP address) Pre-call: re-register, routing of INVITE based on SIP- URL mid-call: re-invite MN2 Page 42

22 Host Identity Protocol (HIP) Source: Semester Project, Roost/Toft/Haraldson IETF drafts, see Underlying ideas for mobility support Separate host identifier (HI, name ) and locator ( IP address ) Dynamic name service or rendezvous server for pre-session mobility Update of mapping of host identifier locator at handovers Mechanism works between transport and network layer In combination with security Host Identity Name space based on public keys Hash of HI 128bit Host Identity Tag attached to packets 4-packet basic exchange (cookies, Diffie-Hellman Key Exchange) Page 43 Host Identity / Host identifier Host Identity in HIP is a public asymmetric key pair. RSA DSA Possible others Host Identifier (HI) is the public key which is used to refer the Host Identity. Statically globally unique. Used for host authentication. Variable length (Depending on cryptographic algorithm). Host Identity Tag (HIT) is a fixed length (128 or 64 bit) representation of a Host Identifier Can be used as IPv6 address Goal: low collision probability Page 44

23 HIP Base exchange Beginning of a HIP connection Consists of a 4-way handshake. Involves : Host authentication IPsec encryption key exchange (Diffie-Hellman) DoS prevention via first handshake After Base exchange: only normal IPsec packets Mobility support via re-direction of Ipsec associations Page 45 Content 1. Background Mobility & Handover Types 2. Link-Layer Hand-over Example: WLAN Network Layer Mobility Support: MIP Motivation, Principles, Messages Performance Enhancements: HMIP MIPv6 4. Higher-Layer Mobility Support Transport Layer Mobility, e.g. mobile SCTP Session-Layer: SIP Host Identity Protocol, HIP 5. Hand-over extensions Multi-homing & flow mobility Context transfer Cross-layer aspects 6. Summary & Outlook Appendix: Experimental Measurements Page 46

24 Multi-homing and flow mobility Multi-homing: Host supports multiple interfaces with potentially different IP addresses E.g. for redundancy purposes (e.g. SCTP) Simultaneous, multiple wireless access techniques Goal: redirect different data-streams via appropriate interfaces only one home address (as host identificator) multiple c/o addresses (one per interface) IP Transport Flow Mobility, e.g. extension of mobile IP (IETF draft): HA contains mapping [home address, flow identifier] c/o address Flows identified by (ranges of) Source IP addresses (CNs) Protocol type (TCP, UDP, etc.) Port Numbers, DSCPs, etc. Flow 1 WLAN Access NW IP2 (WLAN) IP1 (UMTS) UMTS Access NW Flow 2 (Multimedia) Application Server Page 47 MIP extensions: Context Transfer (I) Routing-related service: extension of default routing treatment (e.g. Packet discarding, scheduling, etc.) Context: information on the current state of routing-related service Configuration context: unchanged during session State context: changing over time Context Hierarchy: Context Transfer: re-establish routing related service on a new AP/router Page 48

25 MIP Extensions: Context Transfer (II) Framework (expired seamoby draft): Page 49 Cross-layer aspects of mobility support Mobility support is not only about connectivity Inter-linked with security (authentication, access control/filtering) Inter-linked with QoS support Inter-linked with service control Example IMS scenario SIP level (P-CSCF) has responsibility for service-control, QoS control and access control/filter configuration Mobility support mechanisms must not be transparent to SIP level cross-layer approaches required if lower-layer mobility mechanisms deployed... More on IMS in MM3 Page 50

26 Content 1. Background Mobility & Handover Types 2. Link-Layer Hand-over Example: WLAN Network Layer Mobility Support: MIP Motivation, Principles, Messages Performance Enhancements: HMIP MIPv6 4. Higher-Layer Mobility Support Transport Layer Mobility, e.g. mobile SCTP Session-Layer: SIP Host Identity Protocol, HIP 5. Hand-over extensions Multi-homing & flow mobility Context transfer Cross-layer aspects 6. Summary & Outlook Appendix: Experimental Measurements Page 51 Network Architectures beyond cellular networks Personal Area Networks (PANs) Devices attached to or in vicinity of person group mobility models Wireless communication Between devices within PAN To infrastructure networks Between two PANs Wireless multi-hop communication PAN BT VD Me BT at Br at B CAN at Br B Ro/Br at B at Br B You Ro/Br Third Party at B BT VD BT at Br : Bridge Ro : Router Impact of wireless multi-hop Mutual interference MAC protocol deficiencies Need for modified routing (ad-hoc domain) Page 52 [see

27 Outlook: Future wireless networks Properties of future networks ( 4G ): Heterogeneous access technologies , Bluetooth, cellular, etc. IP-based core network Mobility support on IP layer (complemented by higher-layer methods) Mobile IP one major candidate wireless multi-hop connections Personalization (Personal Area Networks, Personal Networks) Reconfigurability (Software Defined Radio) Context Sensitivity DAB DVB Services and applications IP based core network cellular GSM short range connectivity IMT-2000 UMTS New radio interface Wireline xdsl WLAN type other entities Page 53 References C. Perkins: Mobile IP: Design Principles and Practices. Addison-Wesley, IETF Working groups (see also for RFCs and drafts): Mobile IP: IPsec: IPv6: Others: nemo, mip4, dhcp, seamoby J. Schiller: Mobile Communications. Addison-Wesley, A. Festag, Mobile Internet II, Overview of current mobility approaches (lecture material). TU Berlin, Seok Joo Koh, msctp: Use of SCTP for IP Mobility Support, Presentation, IT Forum, Korea, 2003 H. Schulzrinne, E. Wedlund, Application-Layer Mobility Using SIP. Mobile Computing and Communications Review, Vol. 1, No. 2 Page 54

28 Acknowledgements Lecture notes: Mobile Communciations, Jochen Schiller, Student work (TU Munich, AAU) Stefan Rank (Master Thesis) Rui Martins (Master Thesis) Thorbjørn H. Jørgensen and Lars B. Pedersen (Semester project) Lars Roost, Per Toft, Gustav Haraldson (Semester project) Lecture notes: Wireless communication protocols (R. Prasad, TKM) Page 55 Additional Material Page 56

29 Performance Analysis of Hand-over Mechanisms: Experimental Analysis Based on semester project by Thorbjørn H. Jørgensen and Lars B. Pedersen, Aalborg University, Spring 2004 Page 57 Content 1. Scenarios and Mobility Support Schemes Migrating IP address Mobile IPv4 (Mobile) SCTP 2. Measurement Methodology Approach Parameter definitions 4. Results and Discussion Migrating IP address Mobile IPv4 Mobile SCTP Comparison of schemes Page 58

30 Migrating IP address (I): setup Packet monitor Handover script UDP Packet Streamer BT WLAN BT WLAN Subnet X Subnet X Hand-over only within same subnet Transparent to transport layer Hand-over script based on Linux standard bash script commands Page 59 Migrating IP address (II): Gratuitous ARP Gratuitous ARP Request Protocol Type Request Target Protocol Address Sender Protocol Address Sender Hardware Address 00-E0-2D-59-4A-7C (00-E0-2D C) ARP cache (Layer 2) IP address MAC address E0-2D-59-3D-7B E0-2D-59-4A-7A ARP cache (Layer 2) IP address MAC address E0-2D C E0-2D-59-3D-7B (00-E0-2D-59-4A-7C) (00-E0-2D-59-3D-7B) ARP cache (Layer 2) IP address MAC address E0-2D C E0-2D-59-4A-7A Page 60

31 MIP: setup BT HA FA UDP Packet streamer BT WLAN Mobile Node HADDR: WLAN Subnet X Subnet X WLAN HUT Dynamic MIP FA or MN decapsulation Mobile Node Handover scripts for forcing handover Page 61 SCTP: setup BT WLAN BT SCTP Packet streamer Mobile Node WLAN Subnet X WLAN Subnet X SCTPlib (from sctp.de) Partial support for Mobile extension no dynamic modification of IP addresses of association in current implementation Mobile node Handover script for forcing handover Page 62

32 Measurement Methodology: Packet streamers Handover determined from packet stream With deterministic inter packet time UDP and SCTP packet streamer Packet stream captured on mobile node (Ethereal) SCTP Packet Streamer: Client/Server application Maintain association Reliable transport protocol Flow control mechanisms! Association initiated Association created Handover initiated Shutdown initiated Client INIT INIT ACK COOKIE ECHO COOKIE ACK STREAM PACKET STREAM PACKET STREAM PACKET STREAM PACKET ASCONF ASCONF ACK STREAM PACKET STREAM PACKET STREAM PACKET STREAM PACKET SHUTDOWN SHUTDOWN ACK Server Page 63 Definition of handover delay 1:9 1:8 1:7 1:6 1:5 1:4 1:3 1:2 1:1 1:10 1:20 1:21 1:19 1:18 1:17 1:16 1:15 1:14 1:16 1:13 1:12 1:11 Last packet on NIC 1 First packet on NIC 2 2:40 2:39 2:38 2:37 2:36 2:35 2:34 2:33 2:32 2:31 2:30 1:22 2:29 2:28 0 [s] Handover initiated Handover started Handover ended Handover delay (Soft handover ) Total handover delay (Hard handover ) Page 64

33 Migrating IP address: Results Precision Inter-packet time 5ms Results (w. 95% conf. interv.) Bluetooth WLAN 18.8ms±3.2 (Soft) 31.5ms±2.8 (Hard) WLAN Bluetooth 25.9ms±3.2 (Soft) 60.4ms±2.1 (Hard) Page 65 MIP: handover delay distribution Home BT Foreign WLAN, MN decapsulation problems with packet forwarding FA MN cause long delays in many measurements Page 66

34 SCTP: handover delay distribution BT WLAN in different subnets Problem with long total handover delay (>3s), but not for WLAN BT handover possibly due to inter-working problems between SCTP library and WLAN device driver Page 67 Page 68

35 Page 69 Reference Lars B. Pedersen, Thorbjørn H. Jørgensen: Experimental Analysis of Mobility Support Schemes for vertical Handover, Project Report, 6th semester communication networks, Aalborg University, June For additional experimental investigations: Lars J. Roost, Per N. Toft, Gustav Haraldson: The Host Identity Protocol An experimental evaluation, Project Report, 6th semester communication networks, Aalborg University, June Page 70