MobileNAT (Mobility across Heterogeneous Address Spaces)

Transcription

1 MobileAT (Mobility across Heterogeneous Address Spaces) Presented by Kundan Singh (Columbia University) Joint work with Milind Buddhikot, Adiseshu Hari and Scott Miller Agenda Motivation Architecture Implementation Comparison with current approaches Summary (26 slides, 60 min)

2 Current Trends Private address G Explosive growth in connected devices Heterogeneity Access: , 3G, Ethernet Provider Address space IPv4 vs IPv6 Public vs Private 30Aug02 2

3 The goal Preserve session for 1. inter accesspoint 2. inter subnet 3. interat 4. to 3G network 5. to public network AT Internet Routed IP etwork (5) AT PDS (4) Public Addr A AT Private Address Space (3) Ethernet (1) (2) Accesspoint Router Router with AT 30Aug02 3

4 MobileAT (Mobility across Heterogeneous Address Spaces) Presented by Kundan Singh (Columbia University) Joint work with Milind Buddhikot, Adiseshu Hari and Scott Miller Agenda Motivation Architecture Implementation Comparison with current approaches Summary

5 Problem with IP address TCP association C (corresponding node) IP address overloaded Host identification Routing information Change in IP address breaks TCP/socket connection M (mobile node) moves M 30Aug02 5

6 Two addresses C Two IP addresses Virtual IP (fixed hostid) Actual IP (routable; changes) V= Anchor node (A) Application Socket TCP/UDP IP M A= moves M Actual IP Virtual IP et IF Shim Layer Addr V Addr A 30Aug02 6

7 Packet forwarding mechanisms: tunneling or translation C C V= A V= A moves M moves M A= Tunneling Outer: C=>A or HA=>A Inner: C=>V Header overhead A= Translation More processing overhead ot an issue if AT 1 is already present 1 AT is described later 30Aug02 7

8 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 Aug02 8

9 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 Aug02 9

10 Mobility manager and MIDCOM Internet MIDCOM to control AT rules Mobility manager IP in DHCP response Change of lease DHCP server Mobility manager AT rules AT relay relay relay x x Aug02 10

11 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 30Aug02 11

12 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 30Aug02 12

13 Packet flow Shim AT Shim AT Applicatio n Socket TCP/UDP (1) et IF IP Addr V SHIM Layer Addr A : :1756 (2) :1756 :7088 (3) Internet AT C AT picks up an external IP and port 30Aug02 13

14 Intersubnet 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 30Aug02 14

15 Packet flow after the node moves Shim AT Shim AT Applicatio n Socket TCP/UDP IP (1) :1756 :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 30Aug02 15

16 Intradomain sessions A= C V= A= M Moves AT V= A= M Optimization: new signaling message between two MobileAT clients to route the packets directly 30Aug02 16

17 Interdomain 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 30Aug02 17

18 MobileAT (Mobility across Heterogeneous Address Spaces) Presented by Kundan Singh (Columbia University) Joint work with Milind Buddhikot, Adiseshu Hari and Scott Miller Agenda Motivation Architecture Implementation Comparison with current approaches Summary

19 Implementation: client (Win XP) / 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 (ongoing work) Shimlayer driver to capture DHCP packets and translate IP addresses MobileAT client application acting as DHCP client and server Handles ARP for nodes in other subnets 30Aug02 19

20 Implementation: DHCP server and AT (Linux) Virtual IP range Actual IP range DHCP server AT connection tracking PREROUTIG Destination AT POSTROUTIG 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 30Aug02 20

21 MobileAT (Mobility across Heterogeneous Address Spaces) Presented by Kundan Singh (Columbia University) Joint work with Milind Buddhikot, Adiseshu Hari and Scott Miller Agenda Motivation Architecture Implementation Comparison with current approaches Summary

22 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 Signaling Using DHCP (new options) and a perdomain Mobility Manager (MM) Routing path o change in routers or C; but change in M, AT and DHCP server Dynamic home agent (I.e., the AT) 30Aug02 22

23 Comparison to existing schemes Schemes considered in following chart Mobile IP Extensions: Location Register (MIPLR), Route Optimization (MIPRO) Micromobility schemes IPv6 Cellular IP Hawaii IntraDomain Mobility Protocol (IDMP) Hierarchical Mobile IP (HMIP) Application level mobility mechanism SIP Virtual AT Similar address translation in the client stack Targeted for connection migration where both endpoints implements vat 30Aug02 23

24 Comparison chart MIP CIP Hawaii HMIP (RR) IDMP TeleMIP MIP LR MIP RO SIP IPv6 Mobile AT Virtual AT MIP messaging Intertunnel O O Intratunnel 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 onmobile 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 30Aug02 24

25 Mobile AT Advantages Problems in existing approaches Huge infrastructure change (CIP, IPv6, routers, even deploying FA) ot much discussion on optimizing intradomain sessions Require tunneling overhead, inter, intra or both Triangular routing Modification in C MobileAT approach Addresses rapid growth in enddevices, 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 coexist with MobileIP 30Aug02 25

26 Ongoing work Scalability: Subdivide domains into smaller ATed domains Multiple ATs per domain Security DHCP authentication and Accesspoint authentication/encryption Works with IPsec (AH mode and UDP tunnel) and SSL Paging: Reuse of existing IPmulticast 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 handoff for micromobility Intradomain sessions on interdomain mobility Combined MobileIP and MobileAT client 30Aug02 26

27 Summary Main Ideas 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 InterAT packet flow for interdomain mobility o change in routers or no need for FA Change In M, AT and DHCP server Demonstrated a simple intersubnet mobility 30Aug02 27