Additional Material Suguru Yamaguchi Nara Institute of Science and Technology Department of Information Science 2010 Information Network I/No.4 1
! Protocol Suites for the Internet! Widely used from LANs to WANs! Operating in many systems Computers: UNIX workstations PCs supercomputers PDAs, thermometers, cars, satellites, next-generation mobile phones, home electronics,! Active R&D and standardization IETF (Internet Engineering Task Force) http://www.ietf.org/! Structured as hierarchical protocols The early model is the 5-layer model 2010 Information Network I/No.4 2
Gateway packet forwarding between interconnected network nodes in over the network layer Network Gateway Network Gateway Network Hosts group is directly connected through shared media. Network 2010 Information Network I/No.4 3
OSI TCP/IP Protocol Data Unit Address Application Presentation Application Message / Stream Session Transport Transport Transport Packet Port Network Internet IP Datagram IP address Data Link Network Interface Frame Datalink Address Physical Hardware 2010 Information Network I/No.4 4
! Processing the forwarding of IP datagrams communication with upper layers IP datagram Next hop IP address within the same data link! Basic processing mapping between data link address and next hop address assembling the data link frame controlling the network hardware processing sending and reception! data transmission to hosts within the same data link the network layer is responsible for forwarding data to other networks through gateways 2010 Information Network I/No.4 5
! IPv4 / IPv6 uniquely identifies nodes absorbs differences of the data link layer! Characteristics of IP (Internet Protocol) connectionless service the IP datagram is the transmission unit sender host and receiver host do not hold any particular connection Post type the IP datagram is dumped when an error is detected Best Effort type provides communication between hosts on the internet communication between different networks network interface selection in gateways routing 2010 Information Network I/No.4 6
! network part and host part! each subnet has a different range! 163.221.74.127/24! 203.178.142.0/27 163 221 74 127 0xA3 0xDD 0x4A 0x7F Network part Prefix length Host part 2010 Information Network I/No.4 7
! 128-bit address! Sufficient Internet address space support for the next 25 years for the time being, use of 1/8 of the address space! Aggregatable Global Unicast Address allocation 3 13 32 16 64 bits FP TLA ID NLA ID SLA ID Interface ID 2010 Information Network I/No.4 8
! Large address space! Concept of address scope structured address! Classless! Aggregatable address structure! High expandability 2010 Information Network I/No.4 9
! Hop-by-hop, destination oriented next hop is decided on each gateway next hop output interface assumption : each gateway shares in some way the route information routing algorithm! Forwarding and routing routing information derived by routing algorithm packet forwarding follows routing information 2010 Information Network I/No.4 10
IP module routing forwarding interfaces (input) interfaces (output) routing by choice of network interface output I/F = f(destaddr): f(x) is routing 2010 Information Network I/No.4 11
! Fundamental model provide end-to-end communication between processes process identification <IP address, port> using functions of IP layer! Port identifier of the transport layer 2 octets defined by every transport protocol different allocation in TCP and UDP different purposes even for the same number e.g. 5678/TCP, 5678/UDP! Identification of peer entity (sender IP, receiver IP, protocol number, sender port, receiver port) protocol number defined by standard TCP=6, UDP=17 Host Transport process process Internet Network Interface Hardware 2010 Information Network I/No.4 12
! Internet Transmission Control Protocol telephone type communication full duplex Connection Oriented Virtual Circuit unstructured stream no limitation for message length reliability technologies ensures reliability ensures message sequence order acknowledgement retransmission 2010 Information Network I/No.4 13
! Byte stream semantics byte sequence sent by the start point, byte sequence is outputted by the end point bidirectional : distinguished going and returning! applications can not see the limits of packets! Connection setup / release connection is set up upon agreement of both ends 2010 Information Network I/No.4 14
! Internet User Datagram Protocol post type connectionless Datagram communication does not ensure reliability doesn t guarantee neither reachability nor sequence order applies the case where the user uses IP layer functions as is Best Effort defines maximum message length 2010 Information Network I/No.4 15
! Many other transport layer protocols were developed or standardized RTP, SCTP! IP multiplexes packets of several transport layer protocols. 2010 Information Network I/No.4 16
! Provides direct services to the user! Uses services of the transport layer! e.g. SMTP (Simple Mail Transfer Protocol), FTP (File Transfer Protocol), TELENET, POP (Post Office Protocol), HTTP (HyperText Transfer Protocol),.! Standardized data format Web : HTTP, HTML 2010 Information Network I/No.4 17
! MIME internationalization of character expression! ASN.1 standard borrowed from OSI! XDR industrial standard by Sun! XML standard by W3C! many applications use these standards 2010 Information Network I/No.4 18
! Definition of address in each layer Application Layer space of each application WWW: URL Transport Layer identifies pair peer entity Port 2 octets (unsigned short) Network Layer Host identification Internet Address, IP host address octets Data Link Layer follows each standard In the case of ethernet, definition of ethernet address 2010 Information Network I/No.4 19
! TCP/IP protocol suit! IP (IPv4 & IPv6)! Gateway architecture & routing! TCP and other transport protocols! Application Layer protocols! Newly added layer: presentation layer 2010 Information Network I/No.4 20
2010 Information Network I/No.4 21
! Layer2 (data link layer) provides frame transmission functions in various media. implementation of all frame types for each medium is hard 802.2 (LLC layer) was born within IEEE802 IEEE802 will be studied in the next lecture Network Layer ISO/OSI Local Area Network Definitions (8802) CCITT Datalink Layer Definition Data link Layer Logical Link Control Sublayer Media Access Control Sublayer 8802/3 CSMA/CD 8802/2 LLC 8802/4 Token Bus 8802/5 Token Ring CCITT X.25 (HDLC/LAPB) Physical Layer 2010 Information Network I/No.4 22
! Developers want to use device driver many times Even in different media, developers want to use the same interface and frame = development costs reduction ATM was pioneer ATM will be studied in the next lecture Network Layer signaling data Data link Layer ATM Adaptation Layer abstraction of existing data link (AAL) ATM original mechanism of ATM Physical Layer 2010 Information Network I/No.4 23
! sub-layering is a recent trend does not alter the interface with upper layers use existing data links at their most however, new functions are introduced by sub-layering technical advantages offered by new data link technology strict guidelines by IEEE802! Sub-layering is actually the redefinition of functions through specialization shorten the development period by defining layered shared API structures Network Layer Data link Layer Physical Layer Upper layer API function function function 2010 Information Network I/No.4 24
! The idea of Sub-layering can be expanded to other layers! Layer 3 divides network layer function in 2 sub-layers! Layer 4 packet transmission between physical nodes in network provides logical node model for upper layer e.g.1 This model provides network transparency for mobile nodes. Used in Mobile IP e.g.2 encrypted communication implemented in network layer. provides same interface for upper layer until now. Incorporation of numerous functions in process communication for specific services Real-time transmission, multiple data-path management, performance management, etc.! The recent boom 2010 Information Network I/No.4 25
! Birth of technologies that do not conform to the 7- layer model! What is going to happen when L3 is riding over L3? Emergence of the so-called Tunneling technology recently, tunneling is widely used IPsec / VPN (Virtual Private Network) IP Multicasting Virtual network (Mbone, 6bone), overlay network New issues routing MTU control 2010 Information Network I/No.4 26
TP IP in IP TP IP IP Tunneling NIF NIF NIF The address of the tunneling NIF becomes virtual interface address. 2010 Information Network I/No.4 27
TP TP IP Tunneling NIF IP NIF NIF IP appropriate control and header processing for tunneling NIF virtually connect remote nodes by forwarding datagrams over IP layer contribute to virtual development of network 2010 Information Network I/No.4 28
! Free We can define new layers in-between 2 layers. 4.5 layer service mixing part of session layer service and transport layer 3.5 layer service Not limited to 7 layers We can discuss about several unified layers. Since required functions are diversified, in the end the model also requires flexibility becomes a reference model in the true sense of the term needs different ideas to model design and implementation 2010 Information Network I/No.4 29