Chapter 6 - Mobile Network Layer.ppt111111
- 1. Chapter 6 Mobile Network Layer Compiled by Mikiyas .A 1
- 2. Outlines Mobile IP • Introduction • Mobile IP entities and Terminologies • IP packet delivery • Registration • Tunneling and Encapsulation Introduction to Mobile ad-hoc networks 2
- 3. What is mobile IP •Mobile IP is a protocol developed to support mobility in the Internet. It allows mobile devices, such as laptops, smartphones, and tablets, to maintain connectivity while moving across different IP networks. •It's especially useful in scenarios where devices change their point of attachment to the Internet frequently, such as in wireless LANs or when switching between cellular towers 3
- 4. Requirements(features) for Mobile IP Compatibility - support of the same layer 2 protocols as IP - no changes to current end-systems and routers required - mobile end-systems can communicate with fixed systems Transparency - mobile end-systems keep their IP address - continuation of communication after interruption of link possible -point of connection to the fixed network can be changed -Scalability and Efficiency - only little additional messages to the mobile system required (connection - typically via a low bandwidth radio link) - world-wide support of a large number of mobile systems in the whole Internet Security - authentication of all registration messages 4
- 5. Terminology • Mobile Node (MN) • system (node) that can change the point of connection to the network without changing its IP address • Home Agent (HA) • system in the home network of the MN, typically a router • registers the location of the MN, tunnels IP datagrams to the COA • Foreign Agent (FA) • system in the current foreign network of the MN, typically a router • forwards the tunneled datagrams to the MN, typically also the default router for the MN • Care-of Address (COA) • address of the current tunnel end-point for the MN (at FA or MN) • actual location of the MN from an IP point of view • can be chosen, e.g., via DHCP • Correspondent Node (CN) • communication partner 5
- 6. Mobile IP: Processes • Agent Discovery: To find agents • Home agents and foreign agents advertise periodically on network layer and optionally on datalink, • Registration – Mobile registers its care‐of‐address with home agent. Either directly or through foreign agent – agent sends a reply to the CoA. • Return to Home: – Mobile node deregisters with home agent sets care‐ of‐address to its permanent IP address. • Simultaneous registrations with more than one COA allowed (for handoff). 6
- 7. Cont.. • Tunneling and Routing • Home agent intercepts mobile node's datagrams and forwards them to care‐of‐address . • Care of Address can be the Foreign Agent or it can be collocated in the mobile host • Home agent tells local nodes and routers to send mobile node's datagrams to it • De‐encapsulation: Datagram is extracted and sent to mobile node. 7
- 8. Mobile IP example network 8
- 9. IP Packet Delivery • IP packet delivery refers to the process by which Internet Protocol (IP) packets are transmitted from a source to a destination across a network. • The delivery process involves several steps and components within the network infrastructure to ensure that packets reach their intended destination accurately and efficiently. • Here's an overview of IP packet delivery steps: Packet Encapsulation,Routing,Forwarding,Switching,Transmission, Error Checking, and Acknowledgment. 9
- 10. IP Packet Delivery aim: allow packet from CN to MN 10
- 11. What is Registration ? • Registration is a critical aspect of mobile and network communication • It enabling devices to establish connectivity, inform networks about their current status, and obtain necessary resources for communication. • By following standardized registration procedures, devices can seamlessly integrate into networks and maintain uninterrupted communication services. 11
- 12. Registration 12
- 13. Tunneling and encapsulation • Tunneling and encapsulation are techniques used in networking to transmit data packets over networks that would not normally support that type of packet or to ensure secure transmission of data. • Tunneling is a process that allows the encapsulation of one type of network packet within the payload of another network packet. • This enables the transmission of packets over networks that may not natively support the encapsulated protocol. • Purpose: Tunneling is used for various purposes, including: Connecting networks with different underlying technologies (e.g., IPv4 over IPv6). 13
- 14. Cont.. • Encapsulation involves enclosing data within a specific protocol format for transmission over a network. • It adds a header and possibly a trailer to the original data, forming a new packet structure. • Purpose: Encapsulation helps ensure that data is transmitted efficiently and correctly across the network. • Example: In Internet Protocol (IP) networks, data packets are encapsulated with IP headers containing source and destination IP addresses. 14
- 16. What is DHCP ? • Dynamic Host Configuration Protocol (DHCP) is a network management protocol used to dynamically assign IP addresses and other network configuration parameters to devices on a network. • It simplifies the process of IP address allocation and management by automating the assignment of IP addresses and related configuration settings. 16
- 17. How DHCP Works ? I. Client Initialization: When a device (client) joins a network and needs to obtain an IP address, it sends a broadcast message called a DHCPDISCOVER to discover DHCP servers available on the network. II. DHCP Server Response: DHCP servers on the network receive the DHCPDISCOVER broadcast message and respond with a DHCPOFFER message. This message includes an available IP address and other network configuration parameters, such as subnet mask, default gateway, DNS server addresses, and lease duration. III)Client Request: The client receives multiple DHCPOFFER messages from different DHCP servers and selects one of them. It then sends a DHCPREQUEST message to the selected DHCP server, indicating its acceptance of the offered IP address and configuration parameters. 17
- 18. Cont.. IV) IP Address Assignment: The DHCP server responds to the DHCPREQUEST message with a DHCPACK message, confirming the IP address assignment and providing the client with the network configuration parameters. V) Lease Renewal: The client uses the assigned IP address and configuration settings for a specific lease period, which is typically configurable by the network administrator. Before the lease expires, the client may attempt to renew the lease by sending a DHCPREQUEST message to the DHCP server. VI) Release and Reclamation: When a device disconnects from the network or no longer requires the assigned IP address, it sends a DHCPRELEASE message to the DHCP server to release the IP address lease. The DHCP server then reclaims the IP address and makes it available for assignment to other devices. 18
- 19. DHCP: Dynamic Host Configuration Protocol • Application • simplification of installation and maintenance of networked computers • supplies systems with all necessary information, such as IP address, DNS server address, domain name, subnet mask, default router etc. • enables automatic integration of systems into an Intranet or the Internet, can be used to acquire a COA for Mobile IP • Client/Server-Model • the client sends via a MAC broadcast a request to the DHCP server (might be via a DHCP relay) 19
- 21. Client initialization via DHCP 21
- 22. Mobile Ad hoc Networks • Standard Mobile IP needs an infrastructure • Home Agent/Foreign Agent in the fixed network • DNS, routing etc. are not designed for mobility • Sometimes there is no infrastructure! • remote areas, ad-hoc meetings, disaster areas • cost can also be an argument against an infrastructure! • Main topic: routing • no default router available • every node should be able to forward 22
- 23. Mobile Ad hoc Networks Architecture Single Hop In a single-hop ad hoc network, all communication occurs directly between individual devices within the transmission range of each other. Each device can directly communicate with any other device within its range without needing any intermediate nodes. Multihop In a multi-hop ad hoc network, communication between devices can occur over multiple intermediate hops. If a device wants to communicate with another device that is out of its direct transmission range, it can do so by relaying data through one or more intermediate devices until it reaches the destination. 23
- 24. Questions ? What is the difference between Cellular and Ad hoc Wireless Networks ? 24
- 25. MANETs and mobile IP 25
- 26. Example ad-hoc network Highly dynamic network topology •Device mobility plus varying channel quality •Separation and merging of networks possible •Asymmetric connections possible 26
- 27. MANET Routing MANET (Mobile Ad hoc Network) routing protocols are designed to facilitate communication between mobile devices without the need for a fixed infrastructure. These devices, often referred to as nodes, can dynamically form a network and communicate with each other. MANET routing protocols can be broadly categorized into three types: 1) Proactive (Table-driven) Routing Protocols: 2) Reactive (On-demand) Routing Protocols: 3) Hybrid Routing Protocols: 27
- 28. Traditional routing algorithms • Distance Vector • periodic exchange of messages with all physical neighbors that contain information about who can be reached at what distance • selection of the shortest path if several paths available • Link State • periodic notification of all routers about the current state of all physical links • router get a complete picture of the network • Example • ARPA packet radio network (1973), DV-Routing • every 7.5s exchange of routing tables including link quality • updating of tables also by reception of packets • routing problems solved with limited flooding 28
- 29. Routing in ad-hoc networks • THE big topic in many research projects • Far more than 50 different proposals exist • The most simplest one: Flooding! • Reasons • Classical approaches from fixed networks fail • Very slow convergence, large overhead • High dynamicity, low bandwidth, low computing power • Metrics for routing • Minimal • Number of nodes, loss rate, delay, congestion, interference … • Maximal • Stability of the logical network, battery run-time, time of connectivity 29
- 30. Problems of traditional routing algorithms • Dynamic nature of the topology • frequent changes of connections, connection quality, participants • Limited performance of mobile systems • periodic updates of routing tables need energy without contributing to the transmission of user data, sleep modes difficult to realize • limited bandwidth of the system is reduced even more due to the exchange of routing information • links can be asymmetric, i.e., they can have a direction dependent transmission quality 30
- 31. DSDV (Destination Sequenced Distance Vector, historical) • Early work • on demand version: AODV • Expansion of distance vector routing • Sequence numbers for all routing updates • assures in-order execution of all updates • avoids loops and inconsistencies • Decrease of update frequency • store time between first and best announcement of a path • inhibit update if it seems to be unstable (based on the stored time values) 31
- 32. Dynamic source routing • Split routing into discovering a path and maintaining a path • Route Discover • only if a path for sending packets to a certain destination is needed and no path is currently available • Route Maintenance • only while the path is in use one has to make sure that it can be used continuously • No periodic updates needed! 32
- 33. Dynamic source routing • Path discovery • broadcast a packet with destination address and unique ID • if a station receives a broadcast packet • if the station is the receiver (i.e., has the correct destination address) then return the packet to the sender (path was collected in the packet) • if the packet has already been received earlier (identified via ID) then discard the packet • otherwise, append own address and broadcast packet • sender receives packet with the current path (address list) • Optimizations • limit broadcasting if maximum diameter of the network is known • caching of address lists (i.e. paths) with help of passing packets • stations can use the cached information for path discovery (own paths or paths for other hosts) 33
- 34. See you next class!!! 34