11. IP Mobility 최 양 희 서울대학교 컴퓨터공학부

Transcription

1 11. IP Mobility

2 Introduction Terminal Mobility Person Mobility Network Mobility Internet 2002 Yanghee Choi 2

3 Mobile IP : Why IP addressing scheme optimized for stationary environment point of attachment changes -> IP address changes alternative: host-specific routes goal: maintain transport and higher-layer connections Home Network Router Transit Router Home Foreign Agent Agent (Home address) Foreign Network Care-of Address Mobile Node 2002 Yanghee Choi 3

4 Mobile IP Basic IP level, Routing-based approach Agent Discovery ICMP compatible protocol When moved / returned Agent advertisement / solicitation message Registration With FA and HA Tunneling Encapsulation Home Agent Foreign Agent Router Router Correspondent Node Internet Internet Router Mobile Node 2002 Yanghee Choi 4

5 Home Address Home Agent Base Mobile IP Protocol (Foreign Agent COA) Mobility Binding Foreign Agent Care-of-Address Mobile Node Correspondent Node Data Flow : CN Mobile Node Normal IP Datagram IP Tunneling Local Datagram Forwarding Data Flow : Mobile Node CN Normal IP Datagram 2002 Yanghee Choi 5

6 Base Mobile IP Protocol(2) Home Agent for N1 Foreign Agent for N1 Mobile Node N1 Mobile Node N2 Home Agent for N2 Foreign Agent for N Yanghee Choi 6

7 Message Flows MN FA HA CN Agent Solicitation Agent Advertisement agent discovery Registration Request Registration Request Registration Reply registration Registration Reply Data sent Data received tunneling Decapsulation Encapsulation 2002 Yanghee Choi 7

8 Care-of of-address (COA) The terminal point of tunnel toward a mobile node Foreign Agent COA (for IPv4) Obtained from Foreign Agent Mobile node communicates to home agent through foreign agent Co-located COA (for IPv4, IPv6) Obtained by DHCP, PPP, Externally obtained local address Mobile node communicates directly with its Home Agent 2002 Yanghee Choi 8

9 Agent Discovery mechanism Mobility Agents Advertise their presence via Agent advertisement message (TTL=1) Response to Agent Solicitation with Agent Advertisement message Mobile Nodes (optional) MN may solicit Agent Advertisement message through an Agent Solicitation message MN receives the Agent Advertisement and determines whether it is on its home network or a foreign network If home network, MN deregisters with its home agent If foreign network, MN obtains COA from Agent Advertisement message and registers its new COA with its home agent via the foreign agent 2002 Yanghee Choi 9

10 ARP, Proxy ARP, Gratuitous ARP Proxy ARP used by Home Agent to intercept datagrams destined to the Home Address of any of its registered mobile nodes reply with Home Agent link-address, to ARP request to the mobile node Gratuitous ARP upon registration by a mobile node, home agent sends gratuitous ARP to update ARP caches of nodes on the home network upon returning to home network, the mobile node and its home agent send out gratuitous ARP 2002 Yanghee Choi 10

11 Registration mechanism Mobile Node The MN sends Registration Request message containing the new COA to its HA, via FA Foreign Agent The FA authenticates MN The FA relays Registration Request to HA If the FA receives successful Registration Reply, it makes Mobility binding and relays the Registration Reply to MN Home Agent The HA authenticates MN, and FA Creates or modifies mobility binding for the MN Sends Registration Reply to the the FA 2002 Yanghee Choi 11

12 Registration Extension Authentication Type Length SPI SPI Authenticator SPI (Security Parameter Index) index identifying a security context between two nodes, selects the authentication algorithm, mode, and secret (key) used in computing the Authenticator Authenticator 128 bits MD5 checksum of secret and registration message 2002 Yanghee Choi 12

13 Authentication Mobile - Home Authentication (type 32) Mobile - Foreign Authentication (33) Foreign - Home Authentication (34) 2002 Yanghee Choi 13

14 Tunneling 2002 Yanghee Choi 14

15 Triangular Routing HA is the bottleneck Route optimization Get binding information Home Agent Packets-from-correspondent node routed indirectly through Home Agent Correspondent Node encapsulation Packets-to-correspondent node routed O.K. Foreign Agent Mobile Node 2002 Yanghee Choi 15

16 Route Optimization Location caching By maintaining binding cache Foreign agent smooth handoff Sending a binding update to the previous FA Binding cache updates When HA intercepts a packet from home network HA deduce that the CN(sender) has no binding cache entry HA sends a binding update message to the CN 2002 Yanghee Choi 16

17 Route Optimization in Mobile IP Home Agent Foreign Agent ome Address Care-of Address Mobile Node CN Yes Mobility Binding Cache Mobility Security Association is required between corresponding nodes Tunneling Local Datagram Forwarding 2002 Yanghee Choi 17

18 Route Optimization in Mobile IP(2) Home Agent Foreign Agent ome Address Care-of Address Mobile Node Binding Update Message CN No Mobility Binding Cache 2002 Yanghee Choi 18

19 Smooth Handoff New FA send a binding update to the Previous FA The previous FA re-tunnels Packets tunneled to pre-fa can be forwarded to the new FA CN 5. Binding Update 4. Binding Warning HA FA1 3. Re-tunneling 2. Registration 2. Binding Update, previous FA Notification FA2 MN 1.Registration request 2002 Yanghee Choi 19

20 Mobile IPv6 Mobile IPv4 Concept Mobile node, home agent, foreign link Mobile node s home address Foreign agent Collocated care-of address Care-of address obtained via Agent Discovery, DHCP, or manually Agent Discovery Authenticated registration with home agent Routing to mobile nodes via tunneling Route optimization via separate protocol specification Equivalent Mobile IPv6 Concept Globally routable home address and link-local home address A plain IPv6 router on the foreign link (foreign agent no longer exists) Care-of address obtained via Stateless Address Autoconfiguration, DHCP, or manually Router Discovery (same) Authenticated notification of home agent and other correspondents Routing to mobile node via tunneling and source routing Integrated support for route optimization 2002 Yanghee Choi 20

21 Differences of IPv6 from IPv4 128 bit addresses & Address autoconfiguration No Foreign Agent Some level of Multi-homing guaranteed Smooth Handoff 2002 Yanghee Choi 21

22 Mobility Support in IPv6 CN Internet 3. Packet for MH 5. Binding update MN 6. Data 1. Binding update 4. Encapsulated Forwarding 2. Binding acknowledgement HA 2002 Yanghee Choi 22

23 Mobility Support in IPv6 MN AR HA CN Router Solicitation Router Advertisement Binding Update Intercept & Tunneling Binding Acknowledgement First User Packet (If CN doesn t have binding information of MN) Binding Update User packet using Routing Header 2002 Yanghee Choi 23

24 All-IP 2002 Yanghee Choi 24