1 Kommunikatsiooniteenuste arendus IRT0080 Loeng 6 Avo Ots telekommunikatsiooni õppetool, TTÜ raadio- ja sidetehnika inst.

2 Access Multi-service User Terminal Common Core Network Basic Access Network

3 Architectural Layout Multi-service User Terminal (MUT) Basic Access Network cells Common Core Network Plane Internet IP backbone Managed IP Network Service Network Plane RANs Basic Access Network Plane

4 Typical Broadband IP Model L2TP Tunnel Access PoP ISP INTERNET Carrier IP core Access PoP

5 BAS Broadband ‘Direct’ Access PoP ASP INTERNET Access PoP Carrier IP core

6 Link Layer Mobility Handover is taken care of by the involved BSs (and BSS) of the RAN Applicable only to the same RAN Within IP sub-network Transparent to the network layer –Care-of-Address is retained –No registration activity involved BAN signaling not necessary BS BSS IP Subnet: x.x

7 Micro and Macro Mobility in IP BS BSS BS BSS BS BSS BS BSS IP Subnet: x.x IP Subnet: x.x IP Subnet: x.x IP Subnet: x.x IP Core RAN Root CCN /Internet Macro Domain/Region Micro Domain Subnets

8 Heterogeneous Wireless Networks Internet

9 IP Protocol Stack Application Telnet, FTP, RPC, SIP, SAP, SDP, RTP/RTCP, RTSP HTTP, SMTP, etc. TCP and UDP IP/ICMP, Routing Protocols, Mobile IP, IP Multicast/IGMP, etc. Ethernet, ATM, , HIPERLAN, UMTS, Bluetooth, etc. Presentation Session Transport Network Link Physical User Space Device Drivers and Hardware Operating System

10 IP Mobility No true IP mobility is available L2TP provides limited IP mobility within the boundaries of the specific access network Only MobileIP technology can provide true IP mobility to end users

11 IP Mobility – the Problem Internet Protocol routes packets to their destination according to IP addresses IP addresses are associated with a fixed network location TCP Protocol uses IP addresses and port number to identify a session

12 IP Mobility Problem Mobile Computer at Home Link: Internet Link C xxx Link A xxx Link B xxx

13 IP Mobility Problem Mobile Computer to Foreign Link: Internet Link C xxx Link A xxx Link B xxx

14 IP Mobility Problem Mobile Computer at Foreign Link: Internet Link C xxx Link A xxx Link B xxx Different Subnet Number

15 IP Mobility Problem Mobile Computer at Foreign Link: Internet Link C xxx Link A xxx Link B xxx Different Subnet Number ?

16 IP Mobility –Mobile IP One IP address for identifying a mobile node. The original & permanent IP adress at home link: Home Address One IP address for locating a mobile node. A temporary IP address at current (foreign) link: Care-of Address Transparency for higher layers (including applications) Home Address IPHome Address Home Address Care-of Address Dual Adressing Transparency

A Node that can move from Access Point to Access Point being always reachable for other nodes by his Home Address. a Router at the Home Network where the Mobile Node can register its Care of Address. Static IP Address of the mobile Host in his Home Network (e.g. used to identify TCP connections) Temporary IP Address that identifies the Mobile Node in a visited Network (CoA) The Router in the Foreign Network, that provides CoA Terminology in Mobile IP Mobile Node Home Agent Home Address Care-of Address Foreign Agent The node which is connected to the Mobile Node Correspondent Node for visiting Mobile Nodes

Requirements for Mobility in Internet Mobility Increasing number of users asks for Mobility Support in Internet Transparency Mobility shall be transparent to all Protocol Layers above IP Routing Mobility shall be compatible to all Routing Protocols and shall optimize routes Easy to use Mobility shall be as easy to handle as with Mobile Phones in GSM Security Mobility shall not decrease security in Internet

19 Mobile IP – Basic Mechanisms Discovery of the Care–of Address (CoA) using Router Advertisements Registering the Care–of Address Tunneling to the Care–of Address

20 Mobile IP Scenario Internet R R R Home Link Link A Link B Link C Home Agent Foreign Agent Mobile Node Node C

21 Mobile Node registers at its Home Agent Internet R R R Link B Link C Home Agent Foreign Agent Mobile Node Host C Mobile Node sends Binding Update Home Agent confirms with Binding Acknowledgement Home Link Link A

22 Packet Delivery Internet R R R Link B Link C Home Agent Mobile Node Node C Node C sends to the Home Address of the Mobile Node Home Agent tunnels to Foreign Agent (CoA) Mobile Node sends directly to Node C Foreign Agent Home Link Link A

23 Tunneling Decapsulation Encapsulation Source Destination

24 Internet Home Agent R R R Mobile Node moves Home Network Network A Network B Network C R Router Correspondent Node Mobile Node

25  Mobile Node sends Binding Update  Home Agent confirms with Binding Acknowledgement Mobile Node registers at its Home Agent Internet Home Agent Mobile Node R   R R Network B Network C Network A Correspondent Node

26 Internet  Correspondent Node C initiates connection and sends packets to the Home Address of the Mobile Node  Home Agent intercepts packets and tunnels them to the Mobile Node  Mobile Node sends answer directly to Host C Home Agent R Mobile Node    R R Triangular Routing during Initial Phase Network B Network C Network A Correspondent Node C

27 Internet  Mobile Node sends Binding Update to Correspondent Node C  Now Correspondent Node can address the CoA of the Mobile Node directly Home Agent R Mobile Node   R R Normal Operation by Route Optimization Network B Network C Network A Correspondent Node

28 Internet  Mobile Node sends Binding Updates to the Home Agent and to all the Nodes, he is connected to Home Agent R R  R R Mobile Node moves Network B Network C Network A Network D Correspondent Node Mobile Node

Internet Mobile Node Home Agent 2 Home Agent 3  Mobile Node sends Binding Update to the Home-Agents Anycast Address of its Home Network.  A Home Agent answers with Binding Acknowledgement which contains the Home Agents List Home Agent 1 R R Dynamic Home Agent Address Discovery Home Agent 3 9 Home Agent 1 2 Home Agent 2-3 Home Agents List Priority

 Mobile Node sends Binding Update to the first Home Agent from the Home Agents List  Binding Acknowledgement; Registration OK Registration with selected Home Agent Internet Mobile Node Home Agent 2 Home Agent 3 Home Agent 1 R R Home Agent 3 9 Home Agent 1 2 Home Agent 2-3 Home Agents List Priority

31 Packet Format Mobile IPv6 MN  Correspondent NodeCorrespondent  Node MN

32 Advantages Mobile IPv6 Mobility already considered in design of IPv6 128 bit IPv6-Addresses allows Mobile Node to derive CoA from Router Advertisement easily Stateless Address Autoconfiguration and Neighbor Discovery make FAs and DHCP-Server superfluous IPv6 supports dynamically finding of HA efficiently by means of Anycast Address Integrated IPSec-Functionality in IPv6 makes Authentication of Mobile IPv6 Packets easier (in MIPv4 IPSec is optional, in MIPv6 mandatory)

33 RFC IP Mobility Support (RFC 2002) IP Encapsulation within IP (RFC 2003) Minimal Encapsulation within IP (RFC 2004) Reverse Tunneling for Mobile IP (RFC 2344)... Internet Draft Mobility Support in IPv6 Route Optimization in Mobile IP Requirements on Mobile IP from a Cellular Perspective... Mobile IP in Standardization

34 IPv6 in 3G Networks IM Domain IPv6 PS Domain IPv4 or IPv6 Existing IPv4 Internet SGSN GGSN Mobile Terminal SIP Proxy Server Media/ Signalling Gateway PSTN SIP Client SIP Proxy Server GTP Operators ISP WWW Server

35 IPv6 in Broadband Networks DSLAM ATM IP Core Internet BAS Internet VC – Variable Bit Rate SIP VC – Constant Bit Rate IPv6 Multimedia Domain SIP Serve r Other Operator’s Multimedia Domain Globally routable IPv6 address(es) IPv4 or IPv6 address

36 Broadband/3G Integration Unified infrastructure –No interworking or gateways No addressing problems –Forecasted volumes easy to cater for Leverage application development for maximum returns

37 MobileIPv6 Benefits MobileIPv6 + Broadband ‘Direct’ model is a powerful enabler of IP mobility End-users running services are continuously on-line and contactable while roaming between broadband network access segments

38 MobileIPv6 and Broadband  Without MobileIP, connections from UserA to UserB have to go via ISP A and ISP B  Inefficient routing  Poor scalability  Multiple single-points- of-failure ISP B User A User B ISP A

39 MobileIPv6 and Broadband ISP B User A User B ISP A Initial traffic only passes through ISPs Subsequent traffic direct to Care-of-address Home Agent Holds care-of- address of user B Holds care-of- address of user A

40 IPv6 Transition & Interworking Transition –how we migrate to IPv6 Interworking –how we continue to operate with IPv4 New networks have no transition requirements Transition requirements for core networks met through routine upgrades

41 IPv6 Interworking Interworking multimedia domains –Enabling SIP application interworking –Deploy proxies at the network boundary Interworking network core –Dependent on type of address allocation to end-user –Translation is required where user has no IPv4 address

42 IM Domain IPv6 PS Domain IPv4 or IPv6 Existing IPv4 Internet SGSN GGSN Mobile Terminal SIP Proxy Server Media/ Signalling Gateway PSTN SIP Client SIP Proxy Server GTP Operators ISP WWW Server Interworking Options Potential points of IPv4/IPv6 interworking support

43 NAT-PT Translation DSL Access Network IP Network (IPv4) Access Router (IPv6) End User Equipment (IPv6 only) NAT-PT IPv6 DNS IPv4 DNS DNS exchange initiates communication via translator Communication with IPv4 via translator

44 DSTM Support for native IPv4 DSL Access Network IP Network (IPv4) Access Router (IPv6) End User Equipment (Initially IPv6 only) DHCPv6 End user discovers communication to IPv4 – requests temporary IPv4 address Native communication with IPv4 IPv4 over IPv6 tunnel

45 IPv4 GPRS Container RNC WLAN BS2 Serial Router 2 Ultima HK Live IPv4 MAP Scenario 4: Fixed/Mobile roaming R520 Ethernet Scenario 3: Broadband MobileIPv6 Scenario 2: Wireless broadband IPv6 WLAN BS1 Scenario 1: Fixed broadband IPv6 VOD Local Native IPv6 Network HA Hub 3Hub 2 APPS (WWW, MP3, Quake, DNS) PROXY CN Hub 1 Router 1 Ethernet 6in4 tunnel PC 6in4 tunnel Private IPv4 addresses PC MIPv6

46 Scenario 1: Broadband IPv6 Applications Server DNS Server HK IPv6 Network WLAN Quake IPv6 Local Internet IPv6 MP3 Audio IPv6 VoD

47 Scenario 2: IPv6 meets IPv4 DNS Server IPv6 Network IPv4 Internet IPv6 Network IPv6 Internet IPv4 Internet IPv6 MP3 Audio IP v4

48 Scenario 3: MobileIPv6 Portal Server Database Server Home Agent IPv4 Internet HK IPv6 Network Local News & Weather Home Domain Office Domain WLAN Business News, Shares & Reminders WLAN MIPv6

49 Scenario 4: Inter-technology handover Portal Server Database Server Home Agent IPv4 Internet WLAN HK IPv6 Network GPRS Business News, Shares & Reminders Mobile Domain Low Bandwidth GPRS Office Domain High Bandwidth Business News, Shares & Reminders MIPv6

50 Testbed System

51 IP Mobility Support Basic idea of IP mobility management –understand the issues of network-layer mobility support in IP network –understand the basic design principles underlying all mobility support schemes Internet standard: mobile IPv4, Mobile IPv6 –the operations of MIPv4 –introduction to MIPv6 Fast handover solutions

52 Network Support for Mobility In TCP/IP, the host address plays two roles: –acts as an end-point identifier for connections involving the host a host address should always remain the same –provides routing info for packets destined for the host a host address should change whenever the host moves Goal: support mobility without having to change the protocols in all the millions of hosts currently on the Internet

53 Two Tier Addressing We need an address pair to identify a MH at any time: –Home address for identification –current address for routing How to do two-tier addressing: –not physically done (which requires 8 bytes of address per host) –perform address translation along the way by some specialized agents that cache both addresses.

54 Architecture to Support Mobility Mobile host (MH): a host that moves Home address (HA): a location-independent address for a MH Home network: the network identified by the net id part of the HA of MH. A home net has some special agents for proxy-arp, packet forwarding, address translation etc. to support mobility When a MH moves within its home network, no network- level support is needed since packet forwarding is achieved by bridges When a MH moves across networks, the HA cannot be used for routing, though the HA has to be used for end- point identification by TCP

55 Forwarding Agent Current address must refer to the foreign network when a MH is in a foreign network Packets destined for the MH contain the address of a Forwarding Agent (FA). FA forwards packets to the MH –If FA and MH are directly connected, FA simply replaces the destination address with the Home Address of the MH –otherwise, FA has to forward the packet to other FAs till the packet reaches the MH Note that the router/agent that is the last hop to the MH must be mobility aware, since it has to do the final address translation from FA to MH –example: base stations act as FAs

56 Location Directory Location directory (LD) provides the mapping between the home address and forwarding address for a MH MH is responsible for sending updates to the LD when it moves LD is distributed Typically, the Home network maintains LD for its MHs, though parts of the LD are allowed to be cached by other foreign networks

57 Address Translation When a source communicates with a MH, the MH puts its HA in the destination address field. Somewhere along the route, this has to pass thru an address translation agent (ATA), which converts the HA to the forwarding address. Address Translation can be provided by 2 mechanisms: –IP-IP Encapsulation: encapsulate the original datagram within another datagram that contains the FA address –Loose source routing: indicates intermediate hops over which the datagram must travel to the final destination. In this case, the intermediate hop will be the FA, which then converts the packet address to the final destination –

58 Packet Forwarding Source sends out packets that are addressed to HA of MH ATA intercepts packets and maps HA to FA (using IPIP or LSR) Packets arrive at FA FA remaps address to HA and delivers packets over the last hop At the MH, the packet seems to arrive from Source to HA; thus, transport layer is provided transparency What if the final FA and the MH were co-located ? Optimizations in this case ?

59 Mobile IPv4: RFC2002 Macro-management for mobility –less frequent than once per second –More concerned about long-term performance: whether to allow seamless mobility or not Two scenarios for packet forwarding: –MH to a static host: as usual –a static host to a MH: needs Mobile IP

60 A Quick Mapping for Mobile IPv4 to the Architecture Forwarding agent: co-located with foreign Agent or with MH (if DHCP is used) Location Directory: at home router only Address Translation Agent: co-located with home router location update protocol: caching of LD is not allowed; when a MH moves, only the primary copy is modified

61 Basic Concepts Home agent: a router on a MH’s home network which tunnels datagrams for delivery to the MH when it is away from home, maintains LD for MH Foreign agent: a router on a MH’s visited network which provides routing services to the MH while registered. FA detunnels and delivers datagrams to the MH that were tunneled by the MH’s HA. Care-of Address: termination point of a tunnel toward a MH, for datagrams forwarded to the MH while it is away from home. –Foreign agent care-of address: the address of a foreign agent that MH registers with –co-located care-of address: an externally obtained local address that a MH gets.

62 Protocol Overview Mobility agents (FAs & HAs) advertise their presence MH receives the agent advertisements & determines whether it is on its home net or a foreign net –Home net: MH operates without mobility service –Foreign net: obtains a care-of address on the foreign net (via FA’s agent advertisements or DHCP) if away from home, MH registers its new care-of address with its HA thru a registration request/response process (possibly via a FA). Datagram sent to the MH’s home address: – intercepted by its home agent, –tunneled by the HA to the MH’s care-of address, –detunneled at the tunnel endpoint (either a FA or MH itself), –and finally delivered to the MH In the reverse direction, using standard IP routing.

63 Agent Discovery Method used by a MH to determine whether it is in its home net or a foreign net; may allow MH to determine the foreign agent care-of address Mobile IP extends ICMP router Discovery as its mechanism for Agent Discovery –agent advertisement & agent solicitation Agent advertisement: –lifetime: maximum length of time that the Advertisement is considered valid in the absence of further Advertisement –if sends periodically, allows a MH to miss 3 Adv messages before deleting the agent from its list. –If it can serve as a FA, must announce its FA care of address –HA must always be prepared to serve the MHs for which it is the HA. –FA may announce too busy to handle additional MHs, but must still continually send out the Adv messages. Agent solicitation: must be implemented by a MH

64 Registration A mechanism for MHs to communicate their current reachability info to their home agent MHs use registration to –request forwarding service when it is in a foreign network –inform their HA of their current care-of address –renew a registration which is due to expire –deregister when they return to home registration may be via a FA or directly from the MH. –Via a FA: If a MH is registering a FA care-of address if a MH is using a co-located care-of address and receives an Agent Adv from a FA if the “Registration required” bit is set in the Adv message –directly with HA: MH is using a co-located care-of address and not in the above case when MH returns to home net,

65 Registration Overview Via FA: MH sends a Registration Request to the FA FA receives the request and relays it to the HA HA sends a Registration Reply to the FA to grant/deny the registration request FA processes the Registration Reply and relays it to the MH Directly with HA: exchanges Request/Reply with HA directly After a successful registration: HA creates/modifies the entry for the MH: –MH’s care-of address, remaining lifetime of the registration, ID field from the Registration Reply

66 Routing Consideration Foreign Agent : –maintains a visitor list –when receives an encapsulated datagram, compare the inner destination address to entries in its visitor list; route datagrams. Home Agent : –how to intercept any datagrams on the home net addressed to the MH when the MH is away from home –use Proxy and gratuitous ARP: when a MH is registered on a foreign net, its HA uses proxy ARP to reply to ARP request that seeks the MH’s link-layer address when MH leaves/returns its home net, its HA uses gratuitous ARP to update the ARP caches of nodes on the home net, causing such nodes to associate the link-layer address of the HA with the MH’s home IP address –Proxy ARP: an ARP reply sent by one node on behalf of another in response to an ARP request. The proxy supplies its own link-layer address in the reply. –Gratuitous ARP: an ARP packet sent by a node to spontaneously cause others to update an entry in their ARP cache.

67 Co-located care-off address via DHCP DHCP (RFC1541): –a generic protocol for dynamic host configuration –can be used to obtain care-of IP address, default router address, IP subnet mask of a foreign net, domain, and DNS name –Each net is expected to provide either a DHCP server or relay Steps: –The DHCP client sends a DHCP_DISCOVER or DHCP_REQUEST message –The DHCP server has a pool of available addresses. When it sees an address request, it picks one of the addresses and responds with the DHCP_OFFER message, containing the home address. –The DHCP client receives the address, and responds with a DHCP_REQUEST request confirming the address acceptance. The server then binds the address to the client. The server responds with a DHCP_ACK message. –The DHCP client may proceed with its registration process.

68 Route Optimization Idea: –Correspondent hosts can learn the current care-of address for a MH, and creates a valid binding (LD cache entry) for a MH, and becomes Address Translation Agents –Host can encapsulate packets directly to the care-of address of MH (thus bypassing the HA), just as the HA does in the basic Mobile IP spec; host can also use minimal encapsulation as an abbreviated style of encapsulation (8 bytes addtion to the IP datagram) Two main issues: –updating binding caches only when it received and authenticated the MH’s mobility binding when HA intercepts a datagram and tunnels it to the MH, HA sends a Binding Update message to the sender when FA sees that MH is not on its visitor list, it sends HA a Binding Warning message, advising HA to send a Binding Update message to the MH

69 Route Optimization (contd) Foreign Agent Smooth Handoff (this is so-called fast handover, to be talked further) –In basic Mobile IP, datagrams in flight may be lost during handoff since HA forwarded those packets to the old FA. –Solution: old FA is notified of the MH’s new FA via a Binding Update message from the new FA, and forwards datagrams in flight to the MH’s new care-of address Summary –Forwarding agent: same as basic mobile IP –Location Directory: correspondent hosts can cache LD entries –Address Translation Agent: colocated with correspondent hosts –Location update: HA is responsible for sending Binding Update message

70 IPv6 Mobility Proposal Mobility support is a basic requirement for IPv6 design Key differences from Mobile IPv4: –support for route optimization becomes a fundamental part of the protocol, not an optional part as in Mobile IPv4 –no need to deploy foreign agents any more –packets sent to a MH while away from home are tunneled using an IPv6 Routing header (analogous to loose source routing in IPv4) rather than IP encapsulation –MH is always responsible for delivering binding updates to its correspondence hosts

71 Overview of Mobile IPv6 Forwarding agent: co-located with MHs Location directory: LD is maintained at home router. Cache entries are acquired thru Binding Update messages issued by MHs Address Translation Agent: colocated with all hosts and home routers Location Update: MH is responsible for updating the primary copy and all LD cache entries.

72 Fast Handover So far we only care about the long-term performance, what about short-term transience during the handovers? –Will lose packets in flight, hard for TCP to swallow –Handover across geographically adjacent subnets happen most often in practice Fast handover seeks to solve this problem

73 Idea behind fast handover Set up a forwarding tunnel between the old access router and the new access router The old access router forwards all the packets through the tunnel to the new access router, which delivers them to the MH Several solution proposals so far: –MAC bridge based –Proposal within MIPv6

74 Summary Forwarding agent: co-located with foreign Agent or with MH (if DHCP is used) Location Directory: at home router only Address Translation Agent: co-located with home router location update protocol: caching of LD is not allowed; when a MH moves, only the primary copy is modified Route optimization: never; –triangle routing problem –location info is NOT allowed to be cached due to security concerns

75 Link