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An Overview of Selected Protocols (Courtesy: Dr. Waheed)

An Overview of Selected Protocols (Courtesy: Dr. Waheed). Channel access protocols Network layer level protocols Transport layer level protocols Application layer level protocols Recent work Objective of this review: To help you select one protocol for your term project.

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An Overview of Selected Protocols (Courtesy: Dr. Waheed)

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  1. An Overview of Selected Protocols(Courtesy: Dr. Waheed) • Channel access protocols • Network layer level protocols • Transport layer level protocols • Application layer level protocols • Recent work • Objective of this review: • To help you select one protocol for your term project 1-3-1

  2. Channel Access Protocols • ALOHA • Carrier sense multiple access (CSMA) protocols • Collision-free protocols • Limited contention protocols • Channel access protocol standards • IEEE 802.x standards • All of these protocols deal with “channel access problem” • Allocation of a shared channel among multiple stations • All of these protocols are implemented at medium access sublayer level • MAC layer is part of data link layer 1-3-2

  3. Network Layer Level Protocols • IPv4 • IPv6 • Mobile IP • RSVP • Internet control protocols • ICMP • ARP • RARP • OSPF • BGP 1-3-3

  4. IP Protocol • Along with the Transmission Control Protocol (TCP), IP represents the heart of the Internet protocols • IP is a network-layer protocol that contains • Addressing information and • Some control information that enables packets to be routed • Documented in RFC 791 • IP has two primary responsibilities: • Providing connectionless, best-effort delivery of datagrams through an internetwork; and • Providing fragmentation and reassembly of datagrams to support data links with different maximum-transmission unit (MTU) sizes • IP is a stateless protocol 1-3-4

  5. RSVP: Resource Reservation Protocol • RSVP allows • Multiple senders to transmit to multiple groups of receivers • Individual receivers to switch channels (groups) freely • Optimize BW use while eliminating congestion • RSVP uses multicast routing through spanning trees • Each group is assigned a group address • Sender puts group’s address in packets • Routing algorithm builds a spanning tree of all members of a group • Difference from normal multicast: • Some extra information that is multicast to the group periodically to tell routers along the way to maintain certain data structures 1-3-5

  6. Internet Control Message Protocol (ICMP) • ICMP is used to report unusual events or to test the internet • Several types of ICMP messages • Destination unreachable • Time exceeded • Parameter problem • Source quench: choke packet • Redirect: teach the router about geography • Echo request: ask a machine if it is alive • Echo reply: yes, I’m alive • Timestamp request: same as echo request but with timestamp • Timestamp reply: echo reply with timestamp • Each ICMP message type is encapsulated in an IP packet 1-3-6

  7. Address Resolution Protocol (ARP) • Data link layer hardware does not understand IP addresses • Mostly hosts are connected through Ethernet LANs • All Ethernet cards have a unique 48-bit (data link layer) address • How to map an IP address to data link address? • One solution: use of a configuration file • Other solution: Address Resolution Protocol (ARP) • ARP: • Host that needs to map IP address to Ethernet address broadcasts a packet on the Ethernet, asking “Who owns IP address w.x.y.z?” • Each machine on Ethernet receives this broadcast and checks its IP address • Machine with matching IP address will respond with its Ethernet address to the sender • Almost every machine on internet runs ARP • ARP is defined in RFC 826 1-3-7

  8. Reverse ARP (RARP) • ARP finds Ethernet address corresponding to an IP address • Sometime reverse problem has to be solved: mapping an Ethernet address to IP address • This problem occurs while booting a diskless workstation, which gets its OS binary image from a remote file server • How does it learn its IP address? • This problem is solved by RARP • A newly booted workstation broadcasts its 48-bit Ethernet address and asks for corresponding IP address • RARP server sees this request, looks up Ethernet address in its configuration files, and sends back corresponding IP address • RFC 903 • Advantage: IP address is not needed in memory image • Disadvantage: RARP uses broadcast to reach RARP server; therefore, all networks are required to have one RARP server as it cannot go through routers • Solution: Use BOOTP 1-3-8

  9. Bootstrap Protocol (BOOTP) • It is a UDP/IP based protocol that allows a network user to • Automatically receive an IP address or • Have a diskless workstation boot automatically by • Discovering its own IP address; • Discovering the IP address of a server; and • Obtain the name of a boot file that should be loaded into memory • It uses UDP messages that are forwarded over routers • Bootstrap process has two phases: • IP address discovery and boot file selection phase (BOOTP) • File transfer phase • BOOTP server managed by a network administrator automatically assigns the IP address form a pool of IP addresses • It is a basis for an advanced network manager protocol, Dynamic Host Configuration Protocol (DHCP) 1-3-9

  10. Interior Gateway Routing Protocol: OSPF • Internet consists of autonomous systems (ASes) • Each AS operated by a different organization • Each AS can use any routing algorithm within its network • Still standards help • Simplify boundary between ASes • Reuse of code • A routing algorithm within an AS is called Interior Gateway Protocol • Open Shortest Path First (OSPF) routing algorithm • Successor of link state routing algorithm, which was a successor of Bellman-Ford distance vector routing algorithm • It became a standard in 1990 and many router vendors support it 1-3-10

  11. Exterior Gateway Routing Protocol: BGP • A routing algorithm between ASes is called an Exterior Gateway protocol • Border Gateway Protocol (BGP) is used for routing between ASes • Different from OSPF as routing goals are also different • Gateway routers often need to enforce certain policies • Send and receive all packets to and from the Internet • Do not carry transit packets from foreign ASes • Carry transit traffic from specific ASes, etc. • Example: traffic starting or ending at SUN should not transit Microsoft • Policies are manually configured into each BGP router • BGP router handles transit traffic with three categories of networks: • Stub networks • Have one connection to BGP graph and cannot be used for transit • Multiconnected networks • Have multiple connections but some may refuse transit traffic • Transit networks • These are backbones willing to handle third-party packets 1-3-11

  12. BGP (Cont’d) • Pairs of BGP routers communicated using TCP • BGP is a distance vector protocol but differ from most others, such as RIP • Instead of maintaining just the cost to each destination, each BGP router keeps track of the exact path used • Instead of periodically providing distance info to each neighbor, each BGP router provides exact paths it uses to all other routers 1-3-12

  13. Transport Layer Level Protocols • TCP • UDP • AATM AAL protocols 1-3-13

  14. TCP Protocol • TCP entities exchange data in variable sized segments • Consists of 20-byte header with 32-bit seq. #, followed by data • It can accumulate data from several writes or split data from one write over multiple segments • Two restrictions on the size of a TCP segment • Segment, including 20-byte header should fit in 65,535 byte IP payload • Segment must fit in maximum transfer unit (MTU) of a network to avoid fragmentation/reassembly • Each fragment adds 20 byte segment header • Basic protocol used by TCP entities: sliding window protocol • When sender transmits a segment, it also starts a timer • After receiving segment, the receiver sends an ack segment with an ack # that is equal to next sequence # it expects to receive • If sender timesout before receiving ack, it retransmits the segment 1-3-14

  15. TCP Protocol (Cont’d) • TCP need to handle following problems • Bits and pieces of delayed, duplicate segments that may be fragmented differently • Require special attention to extract the correct segments at receiver • Example: bytes 3072-4095 arrive but cannot be acknowledged until 2048-3071 bytes are received • Retransmitted segments can take different routes resulting in different fragmentations • TCP entity at receiving end is responsible for reliably extracting the original segment even though sporadic delayed duplicate fragments may turn up • Segments may occasionally hit a congested network • A number of algorithms have been implemented in TCP to solve these problems 1-3-15

  16. UDP • This is a connectionless protocol • Encapsulated IP datagram • Useful for applications that need one request and one response • A UDP segment consists of 8 byte header • UDP length includes 8 byte header and data • UDP checksum is optional • 0 if not computed • 1’s complement of the sum of UDP header, data (padded to even number of bytes), and pseudo header 1-3-16

  17. ATM AAL Protocols • If ATM layer’s functionality is similar to network layer, AAL is similar to transport layer • AAL 5 protocol is similar to UDP • Four protocols to handle four classes of service • AAL1 – AAL4 • Requirements for classes C and D were so similar that AAL3 and AAL4 are combined into AAL ¾ • AAL5 proposed by computer industry in contrast to telecommunication industry that proposed AAL1 – AAL3/4 1-3-17

  18. Application Layer Level Protocols • Authentication protocols • DNS • SNMP • E-mail related protocols • NNTP • HTTP • Multimedia related protocols • RTP • RTSP 1-3-18

  19. Recent Protocols • Active IETF working groups in following areas: • Applications • Internet • Operations and management • Routing • Security • Sub-IP • Transport 1-3-19

  20. Applications Area Protocols • Cross Registry Information Service Protocol (CRISP) • Instant Messaging and Presence Protocol (IMPP) • Lightweight Directory Access Protocol (LDAP) • Message Tracking Protocol (MsgTrk) • SIP for Instant Messaging and Presence Leveraging Extension (SIMPLE) 1-3-20

  21. Internet Area • Dynamic Host Configuration Protocol (DHCP) • Extensible Authentication Protocol (EAP) • IP over Cable Data Network (IPCDN) • IP over InfiniBand (IPoIB) • IP Routing for Wireless/Mobile Hosts (MobileIP) • Protocol for Carrying Authentication for Network Access (PANA) • IPv6 1-3-21

  22. Operations and Management Area • IP Flow Information Export (IPFIX) • Resource Allocation Protocol (RAP) • Remote Network Monitoring (RMONMIB) • Configuration Management with SNMP (SNMPConf) • SNMP version 3 (SNMPv3) 1-3-22

  23. Routing Area • Border Gateway Multicast Protocol (BGMP) • Inter-Domain Multicast Routing (IDMR) • Inter-Domain Routing (IDR) • Multicast Source Discovery Protocol (MSDP) • Routing Information Protocol (RIP) • Virtual Router Redundancy Protocol (VRRP) 1-3-23

  24. Security Area • Authenticated Firewall Traversal (AFT) • IP Security Protocol (IPSec) • Kerberized Internet Negotiation of Keys (KINK) • Multicast Security (Msec) • An Open Specification for Pretty Good Privacy (OpenPGP) • Public-Key Infrastructure (PKIX) • Secure Network Time Protocol (STIME) • Transport Layer Security (TLS) 1-3-24

  25. Sub-IP Area • General Switch Management Protocol (GSMP) • IP Over Optical (IPO) • Multiprotocol Label Switching (MPLS) • Provider Provisioned Virtual Networks (PPVPN) 1-3-25

  26. Transport Area • Audio/Video Transport (AVT) • Datagram Congestion Control Protocol (DCCP) • Differentiated Services (DiffServ) • Telephone Number Mapping (ENUM) • IP Telephony (IPTel) • Media Gateway Control (MEGACO) • Multiparty Multimedia Session Control (MMUSIC) • Network File System Version 4 (NFSv4) • Robust Header Compression (ROHC) • Session Initiation Protocol (SIP) • Speech Services Control (SpeechSC) 1-3-26

  27. Other References • http://www.iol.unh.edu/ • http://www.ietf.org/rfc/rfcxx00.txt 1-3-27

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