MobileNAT: A New Technique for Mobility across Heterogeneous Address Spaces

Transcription

1 MobileAT: A ew Technique for Mobility across Heterogeneous Address Spaces Milind M. Buddhikot mbuddhikot@bell-labs.com (Lucent Bell Labs) Joint work with Adiseshu Hari, Kundan Singh, Scott Miller Agenda Motivation Architecture Implementation Comparison with current approaches Summary

2 Current Trends Internet WLA Gateway WLA Gateway Hotspot abc.net Hotspot airport.com Heterogeneity Access: , 3G Large number of providers Address space IPv4 vs IPv6 Public vs Private PDS GGS GGS Explosive growth in connected devices Verizon CDMA2000 Multi-radio capable client CIGULAR GSM/GPRS AWS UMTS Seamless high performance roaming Customer relationship with one provider One bill 23-Sep-03 Milind Buddhikot 2

3 MobileAT: A part of Project IOTA 23-Sep-03 Milind Buddhikot 3

4 MobileAT : Basic Ideas

5 Basic Model Public Addr A C.com Internet PubAddr D Public Address Space Routed Domain M Wired Private Address Space ATed Domain Addr A A S 1 Addr B A Addr C A S 2 S 3 M M 2 Mobility M Wireless M3 M Wired Services (messaging, VoIP call) Private Addr a Three kinds of user sessions: S 1 : Internet sessions S 2 : Intra-domain sessions S 3 : Inter-domain sessions End nodes may offer services Common case: PDAs, laptops, phones do not offer long lived internet services but access services on the net Exception: VOIP ATed domain can be a Layer-3 routed domain or Layer-2 switched domain 23-Sep-03 Milind Buddhikot 5

6 Goal Preserve sessions for 1. inter access-point 2. inter sub-net 3. inter-at 4. to 3G network 5. to public network Movement of end devices AT Internet Public Addr A Routed IP etwork AT (5) AT PDS (4) Private Address Space (3) Ethernet (1) (2) Access-point Router Router with AT 23-Sep-03 Milind Buddhikot 6

7 Problem with IP address TCP association SA=d DA=s SP=b DP=a C DA = d M AT moves M IP address overloaded Host identification Routing information TCP connection characterized by a 5- tuple <SA, DA, SP, DP, TCP> Change in IP address breaks TCP/socket connection SA=s DA=d SA=x DA=d SP=a DP=b SP=a DP=b 23-Sep-03 Milind Buddhikot 7

8 Using Two Addresses C Two IP addresses Virtual IP (fixed host-id) Actual IP (routable; changes) M A p = x A Actual IP Application Socket TCP/UDP IP Shim Layer Addr A v Two types of IP addresses Private: *, 10.*, * Public Four cases: <Private A p, Private A v > <Private A p, Public A v > <Public A p, Private A v > <Public A p, Public A v > A v = a SP DA DP Virtual IP et IF Addr A p 23-Sep-03 Milind Buddhikot 8

9 Intra-domain Mobility for Internet Sessions App Socket TCP IP ew subnet Domain moved to <C, A v, 80, SP> A v, SP SHIM Layer A p, SP A p2, SP Mobile EW Flow C <A A,C, SP, 80> etif A Internet A p1, SP A A OLD Flow M maintains A v A p1 rule A maintains A v, A p1 A A rule. May change SP When M moves to a new subnet, rules need to be changed M: A v A p2 A: A v, A p2 A A 23-Sep-03 Milind Buddhikot 9

10 Mapping Rules for Four Cases Policy P1: Expose M s A v if possible Policy P2: ever expose A v Case I: <Private A p, Private A v > P1: A p A A P2: A p A A Case II: <Private A p, Public A v > P1: A p A v P2: A p A A Case III: <Public A p, Private A v > P1: A p A A P2: A p A A Case IV: <Public A p, Public A v > P1: A p A v P2: A p A A 23-Sep-03 Milind Buddhikot 10

11 Packet forwarding mechanisms: tunneling or translation C C Translation C C Tunneling C A C A A C A v A A p1 C A v A A A p2 C A v M moves M M moves M <A v, A p1 > <A v, A p2 > <A v, A p1 > <A v, A p2 > Tunneling involves less processing overhead but higher header overhead Ex: 8Kbps codec with 20ms packetization 20B payload, 12B RTP, 8B UDP, 20B IP 60B in translate mode vs. 80B in tunnel mode Translate mode better for bandwidth constrained links Tunnel mode simpler to implement as most OS support IP-in-IP tunnels 23-Sep-03 Milind Buddhikot 11

12 Intra-domain mobility for Intra-domain Sessions A p = A v = C A v1 = A p2 = M 4 3 A Moves 2 1 A v1 = A p1 = M All virtual addresses configured to be routed to A C has A v,c configured in DS A applies DAT rule: A v,c A p,c and SAT: A p,m A v,m 23-Sep-03 Milind Buddhikot 12

13 Inter-domain mobility Mobility manager of visited AT fetches the existing connection mapping from mobility manager of the home AT If M moves to public address space, Shim layer acts as visited AT Dynamic home agent: use visited AT as home AT for new session Tunneling between visited and home AT M Visited AT moves Internet M Home AT C 23-Sep-03 Milind Buddhikot 13

14 MobileAT etwork Architecture Change of lease DHCP server Mobility manager Internet AT rules AT ew network element Mobility Manager (MM) DHCP server and relays Change of address signifies need to change AT rules Change conveyed to MM MM employs MIDCOM to control AT rules relay relay relay x x Sep-03 Milind Buddhikot 14

15 MobileAT Implementation

16 Implementation: Client (Win XP/2000) / Application Socket TCP/UDP IP MobileAT Client Server Client MobileAT Client MobileIP Client Addr V / et IF Shim Layer Addr A DHCP server - client etwork and interface selector Unified mobility client (on-going work) Shim-layer driver to capture DHCP packets and translate IP addresses MobileAT client application acting as DHCP client and server Handles ARP for nodes in other sub-nets 23-Sep-03 Milind Buddhikot 16

17 Mobility Client Architecture Graphical User Interface & Monitoring User Level OS Kernel Level OS PPP Support Serial Driver AT Command Set IS-835 Shim PPP Interface MIP State Machine Ethernet etwork Detection etwork Selection Interface Abstraction Layer/API PPP Mobile ATClient TCP/IP Protocol Stack CDMA2000 Sierra 3G1xRTT VP/IPSec Client Driver Multi-interface Mobility Client Driver Ethernet Interface Interface Virtual MobileIP Adaptor VP/ IPSec Control ew code developed, Specifically for 3G integration VP/IPSec integration (e.g. Lucent IPSec Client) Interaction with Existing Windows OS modules Software runs on Windows 2000/XP operating system Approximately 45,000 lines of code, 13,000 of which are Windows DIS kernel networking code 23-Sep-03 Milind Buddhikot 17

18 Implementation: DHCP server and AT (Linux) Virtual IP range Actual IP range DHCP server AT connection tracking PRE-ROUTIG Destination AT POST-ROUTIG Source AT DHCP server to allocate virtual and actual IP Actual IP is based on subnet of DHCP relay agent MM is integrated into DHCP server AT using netfilter, iptables, ip_conntrack and ip_nat modules 23-Sep-03 Milind Buddhikot 18

19 Comparison to Existing Mobility Scheme

20 Similarities/Differences with current proposals Translation mode vs. tunneling Packet size vs processing overhead Two addresses per M; can afford since private addresses o external FA needed Co-located mode MIP uses two public IP addresses! Wasteful Signaling Using DHCP (new options) and a per-domain Mobility Manager (MM) Even more lightweight signaling possible Routing path o change in routers or C; but change in M, AT and DHCP server Dynamic home agent (I.e., the AT) 23-Sep-03 Milind Buddhikot 20

21 Comparison to existing schemes Schemes considered in following chart Mobile IP Extensions: Location Register (MIP-LR), Route Optimization (MIP-RO) Micro-mobility schemes Cellular IP Hawaii Intra-Domain Mobility Protocol (IDMP) Hierarchical Mobile IP (HMIP) IPv6 Fast handoff Application level mobility mechanism SIP Virtual AT Similar address translation in the client stack Targeted for connection/process migration where both end-points implements vat 23-Sep-03 Milind Buddhikot 21

22 Comparison chart MIP CIP Hawaii HMIP (RR) IDMP TeleMIP MIP LR MIP RO SIP IPv6 Mobile AT Virtual AT MIP messaging - - Inter-tunnel O O Intra-tunnel O O Paging O - - UD Host ID HA HA CoA CoA LCoA - - SIP HA CoA virtual signaling Data DHCP/ MM C modify? - M modify? - Router modify? FA FA FA O AT support 1 I I I I on-mobile IP nodes I Triangular route / : yes : no - :/A O: optional I:independent UD: Under Development 1: We assume Mobile IP with UDP tunneling for AT 23-Sep-03 Milind Buddhikot 22

23 Mobile AT Advantages Problems in existing approaches Huge infrastructure change (CIP, IPv6, routers, even deploying FA) ot much discussion on optimizing intra-domain sessions Require tunneling overhead, inter, intra or both Triangular routing even in common case Modification in C MobileAT approach Addresses rapid growth in end-devices, which most likely will have private addresses due to slow deployment of IPv6 Assume the presence of A(P)T in a domain Roaming and services across heterogeneous address spaces Reduce problem space to only private address space Choice between tunneling and address translation Addresses bandwidth limitations of wireless links Use existing protocols (DHCP, ICMP) for signaling Discourage changing routing infrastructure Can co-exist with MobileIP 23-Sep-03 Milind Buddhikot 23

24 Summary ew technique called MobileAT for Intra- and Interdomain mobility Virtual IP for host identification; actual IP for routing Address translation in client as well as in AT Existing protocols like DHCP for signaling Mobility manager to handle nodes in a domain AT acts as a dynamic home agent Inter-AT packet flow for inter-domain mobility o change in routers or no need for FA Change In M, AT and DHCP server Demonstrated a inter-subnet mobility through a complete implementation 23-Sep-03 Milind Buddhikot 24

25 On-going work Scalability: Subdivide domains into smaller AT-ed domains Multiple ATs per domain Security DHCP authentication and Access-point authentication/encryption Works with IP-sec (AH mode and UDP tunnel) and SSL Paging: Re-use of existing IP-multicast based paging Possible deployment issues Changing every M driver (similar to Mobile IP) Mobility to 3G network Location information distribution Allow incremental deployment Other issues Does not solve AT problems where application layer message uses IP address (FTP, SIP, RTSP) Fast hand-off for micro-mobility Intra-domain sessions on inter-domain mobility Combined MobileIP and MobileAT client 23-Sep-03 Milind Buddhikot 25

26 Backup

27 Packet Flow Example

28 Example Address assignment Packet flow when M is private and C is public M moves to a new subnet Packet flow after mobility to a new subnet Packet flow when M and C are in the same AT domain Packet flow when M is private and C is public and M moves to new AT domain 23-Sep-03 Milind Buddhikot 28

29 Address assignment Mobility manager DHCP request (my virtual IP = ) (my Mac address) DHCP server AT DHCP response (your virtual IP = ) (your actual IP = ) DHCP server AT Internet 23-Sep-03 Milind Buddhikot 29

30 Packet flow Shim AT Shim AT Applicatio n Socket TCP/UDP (1) et IF IP Addr V SHIM Layer Addr A : :1756 (2) : :7088 (3) Internet AT C AT picks up an external IP and port 23-Sep-03 Milind Buddhikot 30

31 Inter-subnet mobility DHCP request (my virtual IP = ) (my Mac address) DHCP server DHCP response (your virtual IP = ) (your actual IP = ) change Mobility manager AT rules S: :1756 D: :80 S: :7088 D:same x DHCP server AT Internet C x 23-Sep-03 Milind Buddhikot 31

32 Packet flow after the node moves Shim AT Shim AT Applicatio n Socket TCP/UDP IP (1) : :7088 Addr V SHIM Layer et IF Addr A (2) AT (3) Internet C M application or C do not know about change in actual IP 23-Sep-03 Milind Buddhikot 32

33 Using Two addresses A v = a SP DA DP C Two IP addresses Virtual IP (fixed host-id) Actual IP (routable; changes) A Application Socket TCP/UDP M moves M IP Addr A v Shim Layer A p = x A p = y Actual IP A v = a DA A v = a DA Virtual IP Addr A p SP DP SP DP et IF 23-Sep-03 Milind Buddhikot 33

34 Details of the AT Domain Public Addr A AT ATed Domain Router Router Router Router Stub Domain AP AP AP AP AP AP AP AP AP M ATed domain can be a layer-3 routed domain or Layer-2 switched domain Kinds of mobility Intra-domain Layer-2 within same subnet Layer-3 across subnets Inter-domain Layer-3 mobility across adjacent domains 23-Sep-03 Milind Buddhikot 34

35 Address allocation using DHCP DHCP server x DHCP relay agent Virtual and actual IP allocated using DHCP ew DHCP options M sends current virtual IP address (or if none) in the request Server sends the allocated actual and virtual IP addresses in the response Actual IP is allocated based on relay agent IP x Sep-03 Milind Buddhikot 35

36 Overview of A(P)T C Internet Public Addr Packet processing rules need to be changed in the event of mobility AT Packet processing rule out Private Address Space ( ) x In x x Sep-03 Milind Buddhikot 36

37 Intra-domain sessions A= C V= A= M Moves AT V= A= M Optimization: new signaling message between two MobileAT clients to route the packets directly 23-Sep-03 Milind Buddhikot 37

38 Multi-interface Mobility Client Software Unique client software not available today on the market Seamless intra- and inter- technology handoffs using MobileIP, MobileAT Management of multiple physical interfaces (802.11, 3G/PPP, Ethernet, GPRS) Automated network selection algorithm based on priority, signal strength, and preferred network list Mobile VP capability: IPSec over MobileIP, MobileAT 23-Sep-03 Milind Buddhikot 38