Mobility in IPv6 Networks

Transcription

1 Mobility in IPv6 Networks o Mobility Paradigm o Mobile IPv4 IPv6 o Basic MIPv6 o Handover, Security o Temporal Optimisation

2 VCoIP in Praxis

3 VCoIP in Praxis

4 VCoIP in Praxis

5 IP Mobility Approaches o Application: SIP Handover - SIP-server as application specific home agent o Transport: Mobile SCTP - Stateful transport handover (doubly bound) o Multicast-based IP Mobility Support - Mobile with personal multicast address o Mobile IPv6 - Stateless, transport transparent handover

6 MIPv6 Release Mobility on the Rise?

7 What may we expect? o Devices using Home Address while away o Workspaces roaming between local subnets +Improvements on handover performance +3G Mobiles operating IP + o VoIP/VCoIP conferencing: real-time mobility o Group communication by Mobile Multicast

8 3GPP/UMTS Release 5 Referenz-Modell UMTS Release 5 requires IPv6! GPRS Access Network MS Circuit Switch Access Network PS Domain CS Domain Alternative Access Network Applications & Services *) Legacy mobile signaling Network SCP Multimedia CSCF R-SGW IP Networks Mh Mw Ms CAP Mm Cx HSS *) CSCF Gr Mg Gi Mr Gi EIR IM Domain MRF Gf TE MT BSS/GRAN Gb Gc Gi MGCF T-SGW *) R Um Iu A SGSN GGSN Mc Gi Iu Gn Iu 1 TE MT UTRAN PSTN/ MGW MGW Legacy/External R Uu Nb 2 Mc Mc Iu Nc MSC server GMSC server T-SGW *) Applications & Services *) CAP CAP D HSS *) Mh C R-SGW *) IM Domain is now a sub-set of the PS Domain Signalling Interface Signalling and Data Transfer Interface *) those elements are duplicated for figure layout purpose only, they belong to the same logical element in the reference model

9 IP Mobility? Problem: Preserve Upper Layer (L 4+) Communication when changing IP Subnets Key Aspects: - Mobile Node s (MN) global adressability (fixed Home Address) - Mobile Node s local adressability (changing Care of Address) - Keeping partners informed (updating Correspondent Nodes) - Enabling efficient communication (shortcuts) Approaches: Mobile IPv4: IP Mobility Support for IPv4 (RFC 3344) Mobile IPv6: Mobility Support in IPv6 (RFC 3775/3776)

10 Mobile IP Home Agent Internet Access Router o IPv4 s Design Stationary (Routing-Updates Slow) Mobile Node o Implementation of Mobile Services: Tunneling via Home Agent o IPv6 Potential: - Several Addresses (2 for Mobile Node, many for Mobile Networks) - Flexible Architecture - no dedicated Access-Services (Agents, DHCP)

11 Mobile IPv4 Mobiler Host Kommunikationspartner foreign agent home agent Heimat des mobilen Host

12 Mobile IPv6 Mobiler Host Kommunikationspartner home agent Heimat des mobilen Host

13 Mobile IPv6 ρεγιστε ρ Βινδινγ Υπδατεσ

14 Basic Mobile IPv6 MIPv6 transparantly operates address changes on IP layer by: o MN s stateless configuration of Care of Address in a foreign network and Binding Updates (BUs) with Home Agent (HA) and Correspondent (CNs). o MN continues to use its original Home Address in a Destination Option Header, thereby hiding different routes to the socket layer. o CNs continues to use Home Address of the MN, placing current CoA in a Routing Header as Source Route. o MN, CN & HA keep Binding Cache Tables. o Home-Agent needed as Address Dispatcher.

15 Handover Steps o Layer 2 Handover o L3 Movement Discovery o Local Addressing o Duplicate Address Detection o Binding Update with Home Agent o Binding Update with Correspondent Node

16 Handover Security Binding Udates place a severe security challenge: MN must prove that it owns claimed IP addresses o BU with HA: IPsec Security Association (strong coupling) o BU with CN: Return Routablility Procedure (lightweight coupling) to test correctness of MN s HoA and CoA - HoTI/HoT: MN(Cookie) HA CN (HToken, Cookie) HA MN - CoTI/CoT: MN (Cookie) CN (CToken, Cookie) MN - Finally do BU with Hash(HToken, CToken) invertable by CN

17 VoIP/VCoIP Real-Time Requirements! Latency < 100 ms! Jitter < 50 ms! Packet loss < 1 %! Interruption: 100 ms 1 spoken syllable 100 ms are critical bound

18 Local Handover Measurements: Empirical Results

19 Improvement: L2-Trigger & L2 Handover IP - Reduce - MAX_RA_DELAY_TIME 1 3 ms - MAX_RTR_SOLICITATION_DELAY 1 3 ms b - Schulzrinne et al.: Selective Scan + Cache

20 MIPv6 Handover: Topology Problem o Generally HA and CN are at Significant Distance o Handover Time: t handoff t t = + + local BU of HA BU of CN t t local t CN + 2t HA o Jitter Enhancement: o Essential: Eliminate HA/CN RTT Dependence Jitter t + handoff HA Jitter stationary t CN t CN

21 Predictive Handover: Fast MIPv6

22 Reactive Handover with Proxies: Hierarchical MIPv6

23 Handover Analysis: Predictive vers. Reactive Relevant criteria Handover performance: packet loss, delay + jitter Number of performed handovers Number of processed handovers

24 Handover Performance Simple analytical model: o Compare reactive vers. predictive handover o Characteristic to problem: Router distance t l3 o Charac. to predictive HO: 2tl 3 tl2 o Charac. to reactive HO: t + t l3 L2

25 Stochastic Simulation o Constant bit rate traffic from CN/HA (at 10 ms) o Random perturbations (ξ) at each link o Parameters: - Anticipation Time: <x> = 50 ms, ξ = 30 ms - L2 Handoff: <x> = 50 ms, ξ = 10 ms - Local Links: <x> = 2ms, ξ = 1 ms

26 Simulation: Packet Loss

27 Number of Handovers Relevant quantities: - Cell residence time - Call holding time - AR-to-MAP ratio Modelling assumptions: - Cell residence & call holding time exp. distributed (homogeneous distribution)

28 Expected # of Handovers Analytical result: ρ = Call-to-mobility factor k = AR-to-MAP ratio 1 1 E[ HO] = kρ + 2 k ρ

29 Handover Prediction Analysis: Mobility Simulation Models: o Random Waypoint o Random Direction (both with & without boundaries)

30 Handovers

31 Erroneous Predictions About 50 % Bad Predictions

32 Additional Topics HA Autodiscovery Multihoming Mobile Multicasting Seamless Context Transfers Mobility Support in NAT-PT MIPv6 Management References Hesham Soliman: Mobile IPv6, Addison Wesley,