CMPE 257 Wireless and Mobile Networking Katia Obraczka Computer Engineering UCSC Baskin Engineering Lecture 8 CMPE 257 Winter 11 1 Announcements Student presentations Security Jim Seth security in sensor networks Chris security at the MAC layer DTNs Phillip Rance Mobility management Tyler Niosha Energy management Mohamed Hybrid networks Gregg CMPE 257 Winter 11 2 Student Presentations March 7 Feb 28 Mobility management Tyler and Niosha March 2 DTNs Philip and Rance Hybrid networks Gregg Energy management Mohamed March 9 Security Jim March 14 Security Chris and and Seth CMPE 257 Winter 11 3 Today Wireless internetworking CMPE 257 Winter 11 4 Wireless Internetworking Extension of Internet services to wireless mobile users Challenges Wireless medium Node mobility TCP IP stack CMPE 257 Winter 11 5 Mobility IP assumes fixed nodes Hierarchical addresses IP address network number host number IP address uniquely identifies host s PoA Host must attach to network specified by its IP address to send receive datagrams But what if nodes move Change address How about packets destined to them CMPE 257 Winter 11 6 Mobile IP Addresses redirection Manages mobility at the IP layer Hides mobility from upper layers CMPE 257 Winter 11 7 Mobile IP Goals Nodes can receive datagrams no matter where they attach to the Internet IMHP Internet Mobile Host Protocol as Mobile IP precursor CMPE 257 Winter 11 8 Last hop Mobility Mobile IP is the Internet standard for lasthop mobility support in IP networks RFC 2290 How do we deliver IP packets when the endpoints move Mobile host must be able to communicate after changing its link layer point of attachment Mobile host must be able to communicate using its permanent home IP address CMPE 257 Winter 11 9 Mobile IP Design Issues Issues Impact on IP addressing Impact on routing Impact on higher layers Key design considerations Scale Compatibility Transparency CMPE 257 Winter 11 10 Terminology Home Agent HA Foreign Agent FA HN CH Mobile Host MH CMPE 257 Winter 11 11 Terminology Cont d Similar to cellular Mobile Node MN or MH node changing its PoA Correspondent Host CH Home Network HN and Foreign Network FN CMPE 257 Winter 11 12 Terminology Cont d Mobility Agents Home Agent HA router on MN s HN that tunnels datagrams to MH when away and keeps MH s current location info Foreign Agent FA router on foreign network delivers datagrmas to MH while on FN Home Address HoA and Care of Address CoA HoA MH s permanent address on HN CoA MH s temporary address on FN CMPE 257 Winter 11 13 Care of Address FA based MN s address is its current FA s address FN based Locally assigned address in FN E g DHCP address What s the difference CMPE 257 Winter 11 14 Mobile IP Basic Operation MH normally uses its home address HoA When MH visits a foreign network Registration with FA Discover mobile agent and CoA Registration with HA Binding update HoA CoA Communicating with MN use HoA HA forwards packet from HoA to CoA CMPE 257 Winter 11 15 Discovering Agents Agents periodically beacon advertisements CMPE 257 Winter 11 16 Agent Discovery Agent advertisement beaconing Mobile agent broadcast agent advertisement at regular intervals I am here Agent solicitation MH can poll anyone here Mobile agent responds to poll CMPE 257 Winter 11 17 Discovering Agents MH polls agent responds CMPE 257 Winter 11 18 Agent Advertisement Follows ICMP router advertisement message List one or more available care of addresses Inform the MN about special features provided by FA Example Alternative encapsulation techniques header compression CMPE 257 Winter 11 19 Registration CMPE 257 Winter 11 20 Registering When away MH registers its CoA with HA binding update Binding HoA CoA Binding has a lifetime CMPE 257 Winter 11 21 Registration Process MH sends a registration request with CoA HA authenticates request HA approves or disapproves the request HA adds necessary information to its routing table HA sends registration reply back to MH CMPE 257 Winter 11 22 Registration Process cont d In the case of FA based CoA FA is involved in registration FA is also involved in packet forwarding Encapsulation Tunneling CMPE 257 Winter 11 23 Tunneling HA tunnels datagrams destined to MN when MN is away Datagrams sent to MH directly Or sent to FA which forwards to MN s CoA Tunnel terminates at MH s CoA either the MH or the FA CMPE 257 Winter 11 24 Tunneling SRC Tunneled Data Packet HA keeps binding between MH and CoA CMPE 257 Winter 11 25 Encapsulation Tunneling requires encapsulation Sending the original packet CH MH in another packet HA CoA Default encapsulation mechanism IP within IP tunnel Tunnel header new IP header inserted by the tunnel source home agent Destination IP CoA CMPE 257 Winter 11 26 Tunneling in Mobile IP CMPE 257 Winter 11 27 The Triangle Routing Problem Aka dogleg routing MH CH direct CH MH CH HA MH Inefficient Solution route optimization Deliver binding updates directly to CH CMPE 257 Winter 11 28 Route Optimization Binding caches Nodes can keep caches with CoA for MHs If node has entry for MH sends data directly Otherwise triangulates with HA Binding cache entries have TTL HA FA or MH can send binding cache updates to CH CMPE 257 Winter 11 29 Simultaneous Bindings MN can register multiple CoA swith HA Why De registration Explicit Implicit CMPE 257 Winter 11 30 Handoffs MH moving among FN New CoA registered with HA Previous FA not necessarily notified Old registration will expire New data delivered to new CoA In flight data Dropped and retransmitted by upper layers or FA notified of new CoA FA forwards data to new CoA CMPE 257 Winter 11 31 Types of Handoffs MN initiated Handoff managed by MN MN measures signal strength to AP Decides target AP and switchs over Network initiated APs decide when to hand over and to whom CMPE 257 Winter 11 32 Handoff Signaling Forward handoff Target AP contacts current AP to initiate handoff Backward handoff Current AP contacts the target AP CMPE 257 Winter 11 33 Handoff Delay 3 components Detect need of handoff Link establishment between MN and new AP Registration with HA Pre and post registration handoffs Pre registration registers MN with HA before handoff Post registration HA registration happens after handoff CMPE 257 Winter 11 34 Authentication Malicious nodes can infiltrate FNs Mobile IP registration includes authentication info exchange MH HA MH FA HA FA Protection against replay attacks Timestamp and nonces CMPE 257 Winter 11 35 Mobility Support in IPv6 Route optimization is