DOCSLIB.ORG

A Protocol for Packet Network Intercommunication”

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Protocol for Packet Network Intercommunication” Lecture 9: Internetworking CSE 123: Computer Networks Aaron Schulman HW 1 due TODAY Combing Networks ● Main challenge is heterogeneity of link layers: u Addressing » Each network media has a different addressing scheme u Bandwidth » Modems to teraBits u Latency » Seconds to nanoseconds u Frame size » Dozens to thousands of Bytes u Loss rates » Differ By many orders of magnitude u Service guarantees » “Send and pray” vs reserved Bandwidth CSE 123 – Lecture 8: From networks to Internetworks 2 Internetworking ● Cerf & Kahn74, “A Protocol for Packet Network Intercommunication” u Foundation for the modern Internet ● Routers forward packets from source to destination u May cross many separate networks along the way ● All packets use a common Internet Protocol u Any underlying data link protocol u Any higher layer transport protocol CSE 123 – Lecture 8: From networks to Internetworks 3 TCP/IP Protocol Stack host host HTTP Application Layer HTTP TCP Transport Layer TCP router router I I Network Layer I I P P P P Ethernet Ethernet SONET SONET Ethernet Ethernet interface interface interfaceLink Layerinterface interface interface CSE 123 – Lecture 9: Internetworking 4 IP Networking Router WiFi Ethernet data packet data packet Eth IP TCP HTTP FDDI IP TCP HTTP CSE 123 – Lecture 9: Internetworking 5 Routers ● A router is a store-and-forward device u Routers are connected to multiple networks u On each network, looks just like another host u A lot like a switch, But supports multiple datalink layers and makes decisions at the network layer ● Must Be explicitly addressed By incoming frames (L2) u Not at all like a switch, which is transparent u Removes link-layer header, parses IP header (L3) ● Looks up next hop, forwards on appropriate network u Each router need only get one step closer to destination CSE 123 – Lecture 9: Internetworking 6 IP Philosophy ● Impose few demands on network u Make few assumptions aBout what network can do u No QoS, no reliaBility, no ordering, no large packets u No persistent state aBout communications; no connections ● Manage heterogeneity at hosts (not in network) u Adapt to underlying network heterogeneity u Re-order packets, detect errors, retransmit lost messages… u Persistent network state only kept in hosts (fate-sharing) ● Service model: Best effort, a.k.a. send and pray CSE 123 – Lecture 9: Internetworking 7 IP Packet Header 0 15 16 31 ver HL TOS length R M D identification E F F offset S TTL protocol header checksum 20 bytes source address destination address options (if any) data (if any) CSE 123 – Lecture 9: Internetworking 8 Version field ● Which version of IP is this? u Plan for change u Very important! ● Current versions u 4: most of Internet today u 6: new protocol with larger addresses u What happened to 5? Standards Body politics. CSE 123 – Lecture 9: Internetworking 9 Header length ● How Big is IP header? u Counted in 32-bit words u VariaBle length » Options u Engineering consequences of variaBle length… ● Most IP packet headers are 20 Bytes long CSE 123 – Lecture 9: Internetworking 10 Type-of-Service ● How should this packet be treated? u Care/don’t care for delay, throughput, reliaBility, cost u How to interpret, how to apply on underlying net? u Largely unused until 2000 (hijacked for new purposes, ECN & Diffserv) CSE 123 – Lecture 9: Internetworking 11 Length ● How long is whole packet in Bytes? u Includes header u Limits total packet to 64K u Redundant? CSE 123 – Lecture 9: Internetworking 12 TTL (Time-to-Live) ● How many more routers can this packet pass through? u Designed to limit packet from looping forever ● Each router decrements TTL field ● If TTL is 0 then router discards packet CSE 123 – Lecture 9: Internetworking 13 Protocol ● Which transport protocol is the data using? u i.e. how should a host interpret the data ● TCP = 6 ● UDP = 17 CSE 123 – Lecture 9: Internetworking 14 IP Checksum ● Header contains simple checksum u Validates content of header only ● Recalculated at each hop u Routers need to update TTL u Hence straightforward to modify ● Ensures correct destination receives packet CSE 123 – Lecture 9: Internetworking 15 So what does IP do? ● Addressing ● Fragmentation u E.g. FDDI’s maximum packet is 4500 Bytes while Ethernet is 1500 Bytes, how to manage this? ● Some error detection ● Routers only forward packets to next hop u They do not: » Detect packet loss, packet duplication » ReassemBle or retransmit packets ● Today we’ll talk aBout fragmentation CSE 123 – Lecture 9: Internetworking 16 For Next Time ● Read 3.2.5 in P&D ● Homework 1 due TODAY ● Homework 2 out on Monday ● Project 1 due in 1.5 weeks! CSE 123 – Lecture 9: Internetworking 17.
Load more

Recommended publications
  • Lecture 10: Switching & Internetworking
    Lecture 10: Switching & Internetworking CSE 123: Computer Networks Alex C. Snoeren HW 2 due WEDNESDAY Lecture 10 Overview ● Bridging & switching ◆ Spanning Tree ● Internet Protocol ◆ Service model ◆ Packet format CSE 123 – Lecture 10: Internetworking 2 Selective Forwarding ● Only rebroadcast a frame to the LAN where its destination resides ◆ If A sends packet to X, then bridge must forward frame ◆ If A sends packet to B, then bridge shouldn’t LAN 1 LAN 2 A W B X bridge C Y D Z CSE 123 – Lecture 9: Bridging & Switching 3 Forwarding Tables ● Need to know “destination” of frame ◆ Destination address in frame header (48bit in Ethernet) ● Need know which destinations are on which LANs ◆ One approach: statically configured by hand » Table, mapping address to output port (i.e. LAN) ◆ But we’d prefer something automatic and dynamic… ● Simple algorithm: Receive frame f on port q Lookup f.dest for output port /* know where to send it? */ If f.dest found then if output port is q then drop /* already delivered */ else forward f on output port; else flood f; /* forward on all ports but the one where frame arrived*/ CSE 123 – Lecture 9: Bridging & Switching 4 Learning Bridges ● Eliminate manual configuration by learning which addresses are on which LANs Host Port A 1 ● Basic approach B 1 ◆ If a frame arrives on a port, then associate its source C 1 address with that port D 1 ◆ As each host transmits, the table becomes accurate W 2 X 2 ● What if a node moves? Table aging Y 3 ◆ Associate a timestamp with each table entry Z 2 ◆ Refresh timestamp for each
    [Show full text]
  • Wifi Direct Internetworking
    WiFi Direct Internetworking António Teólo∗† Hervé Paulino João M. Lourenço ADEETC, Instituto Superior de NOVA LINCS, DI, NOVA LINCS, DI, Engenharia de Lisboa, Faculdade de Ciências e Tecnologia, Faculdade de Ciências e Tecnologia, Instituto Politécnico de Lisboa Universidade NOVA de Lisboa Universidade NOVA de Lisboa Portugal Portugal Portugal [email protected] [email protected] [email protected] ABSTRACT will enable WiFi communication range and speed even in cases of: We propose to interconnect mobile devices using WiFi-Direct. Hav- network infrastructure congestion, which may happen in highly ing that, it will be possible to interconnect multiple o-the-shelf crowded venues (such as sports and cultural events); or temporary, mobile devices, via WiFi, but without any supportive infrastructure. or permanent, absence of infrastructure, as may happen in remote This will pave the way for mobile autonomous collaborative sys- locations or disaster situations. tems that can operate in any conditions, like in disaster situations, WFD allows devices to form groups, with one of them, called in very crowded scenarios or in isolated areas. This work is relevant Group Owner (GO), acting as a soft access point for remaining since the WiFi-Direct specication, that works on groups of devices, group members. WFD oers node discovery, authentication, group does not tackle inter-group communication and existing research formation and message routing between nodes in the same group. solutions have strong limitations. However, WFD communication is very constrained, current imple- We have a two phase work plan. Our rst goal is to achieve mentations restrict group size 9 devices and none of these devices inter-group communication, i.e., enable the ecient interconnec- may be a member of more than one WFD group.
    [Show full text]
  • Internetworking and Layered Models
    1 Internetworking and Layered Models The Internet today is a widespread information infrastructure, but it is inherently an insecure channel for sending messages. When a message (or packet) is sent from one Website to another, the data contained in the message are routed through a number of intermediate sites before reaching its destination. The Internet was designed to accom- modate heterogeneous platforms so that people who are using different computers and operating systems can communicate. The history of the Internet is complex and involves many aspects – technological, organisational and community. The Internet concept has been a big step along the path towards electronic commerce, information acquisition and community operations. Early ARPANET researchers accomplished the initial demonstrations of packet- switching technology. In the late 1970s, the growth of the Internet was recognised and subsequently a growth in the size of the interested research community was accompanied by an increased need for a coordination mechanism. The Defense Advanced Research Projects Agency (DARPA) then formed an International Cooperation Board (ICB) to coordinate activities with some European countries centered on packet satellite research, while the Internet Configuration Control Board (ICCB) assisted DARPA in managing Internet activity. In 1983, DARPA recognised that the continuing growth of the Internet community demanded a restructuring of coordination mechanisms. The ICCB was dis- banded and in its place the Internet Activities Board (IAB) was formed from the chairs of the Task Forces. The IAB revitalised the Internet Engineering Task Force (IETF) as a member of the IAB. By 1985, there was a tremendous growth in the more practical engineering side of the Internet.
    [Show full text]
  • Guidelines for the Secure Deployment of Ipv6
    Special Publication 800-119 Guidelines for the Secure Deployment of IPv6 Recommendations of the National Institute of Standards and Technology Sheila Frankel Richard Graveman John Pearce Mark Rooks NIST Special Publication 800-119 Guidelines for the Secure Deployment of IPv6 Recommendations of the National Institute of Standards and Technology Sheila Frankel Richard Graveman John Pearce Mark Rooks C O M P U T E R S E C U R I T Y Computer Security Division Information Technology Laboratory National Institute of Standards and Technology Gaithersburg, MD 20899-8930 December 2010 U.S. Department of Commerce Gary Locke, Secretary National Institute of Standards and Technology Dr. Patrick D. Gallagher, Director GUIDELINES FOR THE SECURE DEPLOYMENT OF IPV6 Reports on Computer Systems Technology The Information Technology Laboratory (ITL) at the National Institute of Standards and Technology (NIST) promotes the U.S. economy and public welfare by providing technical leadership for the nation’s measurement and standards infrastructure. ITL develops tests, test methods, reference data, proof of concept implementations, and technical analysis to advance the development and productive use of information technology. ITL’s responsibilities include the development of technical, physical, administrative, and management standards and guidelines for the cost-effective security and privacy of sensitive unclassified information in Federal computer systems. This Special Publication 800-series reports on ITL’s research, guidance, and outreach efforts in computer security and its collaborative activities with industry, government, and academic organizations. National Institute of Standards and Technology Special Publication 800-119 Natl. Inst. Stand. Technol. Spec. Publ. 800-119, 188 pages (Dec. 2010) Certain commercial entities, equipment, or materials may be identified in this document in order to describe an experimental procedure or concept adequately.
    [Show full text]
  • An Architecture for High-Speed Packet Switched Networks (Thesis)
    Purdue University Purdue e-Pubs Department of Computer Science Technical Reports Department of Computer Science 1989 An Architecture for High-Speed Packet Switched Networks (Thesis) Rajendra Shirvaram Yavatkar Report Number: 89-898 Yavatkar, Rajendra Shirvaram, "An Architecture for High-Speed Packet Switched Networks (Thesis)" (1989). Department of Computer Science Technical Reports. Paper 765. https://docs.lib.purdue.edu/cstech/765 This document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact [email protected] for additional information. AN ARCIITTECTURE FOR IDGH-SPEED PACKET SWITCHED NETWORKS Rajcndra Shivaram Yavalkar CSD-TR-898 AugusL 1989 AN ARCHITECTURE FOR HIGH-SPEED PACKET SWITCHED NETWORKS A Thesis Submitted to the Faculty of Purdue University by Rajendra Shivaram Yavatkar In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy August 1989 Il TABLE OF CONTENTS Page LIST OF FIGURES Vl ABSTRACT ................................... Vlll 1. INTRODUCTION 1 1.1 BackgroWld... 2 1.1.1 Network Architecture 2 1.1.2 Network-Level Services. 7 1.1.3 Circuit Switching. 7 1.1.4 Packet Switching . 8 1.1.5 Summary.... 11 1.2 The Proposed Solution. 12 1.3 Plan of Thesis. ..... 14 2. DEFINITIONS AND TERMINOLOGY 15 2.1 Components of Packet Switched Networks 15 2.2 Concept Of Internetworking .. 16 2.3 Communication Services .... 17 2.4 Flow And Congestion Control. 18 3. NETWORK ARCHITECTURE 19 3.1 Basic Model . ... 20 3.2 Services Provided. 22 3.3 Protocol Hierarchy 24 3.4 Addressing . 26 3.5 Routing .. 29 3.6 Rate-based Congestion Avoidance 31 3.7 Responsibilities of a Router 32 3.8 Autoconfiguration ..
    [Show full text]
  • MODULE V Internetworking
    MODULE V Internetworking: Concepts, Addressing, Architecture, Protocols, Datagram Processing, Transport-Layer Protocols, And End-To-End Services Computer Networks and Internets -- Module 5 1 Spring, 2014 Copyright 2014. All rights reserved. Topics d Internet concept and architecture d Internet addressing d Internet Protocol packets (datagrams) d Datagram forwarding d Address resolution d Error reporting mechanism d Con®guration d Network address translation Computer Networks and Internets -- Module 5 2 Spring, 2014 Copyright 2014. All rights reserved. Topics (continued) d Transport layer protocol characteristics and techniques d Message transport with the User Datagram Protocol (UDP) d Stream transport with the Transmission Control Protocol (TCP) d Routing algorithms and protocols d Internet multicast and multicast routing Computer Networks and Internets -- Module 5 3 Spring, 2014 Copyright 2014. All rights reserved. Internet Concept And Internet Architecture What Is The Internet? d Users see it as services and applications ± Web and e-commerce ± Email, texting, instant messenger ± Social networking and blogs ± Music and video download (and upload) ± Voice and video teleconferencing d Networking professionals see it as infrastructure ± Platform on which above services run ± Grows rapidly Computer Networks and Internets -- Module 5 5 Spring, 2014 Copyright 2014. All rights reserved. Growth Of The Internet 1000M . .. .. .. 900M ... .. .. .. ... .. 800M .. .. .. ... .. 700M .. .. .. ... .. 600M .. .. .. ... .. 500M .. .. .. ... .. .
    [Show full text]
  • Internetworking
    Carnegie Mellon Internetworking 15-213: Introduc0on to Computer Systems 19th Lecture, Oct. 28, 2010 Instructors: Randy Bryant and Dave O’Hallaron 1 Carnegie Mellon A Client-Server Transac8on 1. Client sends request Client Server process process Resource 4. Client 3. Server sends response 2. Server handles handles response request Note: clients and servers are processes running on hosts (can be the same or different hosts) Most network applica8ons are based on the client-server model: . A server process and one or more client processes . Server manages some resource . Server provides service by manipulang resource for clients . Server ac0vated by request from client (vending machine analogy) 2 Carnegie Mellon Hardware Organiza8on of a Network Host CPU chip register file ALU system bus memory bus I/O main MI bridge memory Expansion slots I/O bus USB graphics disk network controller adapter controller adapter mouse keyboard monitor disk network 3 Carnegie Mellon Computer Networks A network is a hierarchical system of boxes and wires organized by geographical proximity . SAN (System Area Network) spans cluster or machine room . Switched Ethernet, Quadrics QSW, … . LAN (Local Area Network) spans a building or campus . Ethernet is most prominent example . WAN (Wide Area Network) spans country or world . Typically high-speed point-to-point phone lines An internetwork (internet) is an interconnected set of networks . The Global IP Internet (uppercase “I”) is the most famous example of an internet (lowercase “i”) Let’s see how an internet is built from the ground up 4 Carnegie Mellon Lowest Level: Ethernet Segment host host host 100 Mb/s 100 Mb/s hub port Ethernet segment consists of a collec8on of hosts connected by wires (twisted pairs) to a hub Spans room or floor in a building Operaon .
    [Show full text]
  • Connecting Computers with Packet Switching
    LECTURE 1 Connecting Computers with Packet Switching 1 This lecture discusses different ways of interconnecting links (of the same kind) to build a simple computer network. To achieve this task, we will use a device called a switch, and discuss several different ways of switching to move data across a network. We focus on packet switching, discussing its main ideas and principles. This lecture assumes that the reader is familiar with standard ways of communicating digital information (bits and link-layer frames) over a single link. Most networking texts cover this material in depth; we provide a short summary of the essential ideas in L0. ! 1.1 Interconnections The rather limited scope—in terms of physical distance, number of connected hosts, and amount of sustainable traffic—of single-link networks leads us to examine ways of inter- connecting single-link communication media together to form larger networks of comput- ers. We start by discussing a few different interconnection techniques. The fundamental problem is that the most obvious way to build a computer network—by connecting each pair of computers with a dedicated link—is both prohibitively expensive (because of the sheer number of links required, a number that grows quadratically with the network size) and technically challenging (because signals attenuate with distance, requiring ways to regenerate information across large distances). The solution to these problems is to de- velop ways to share links between different communicating nodes, and to regenerate the information being communicated as it travels across the network. The key component used for such interconnections is a switch, which is a specialized computing device that receives data frames (of bits) that arrive over links, processes them, and forwards them over one (or more) other links.
    [Show full text]
  • ETSI White Paper on Ipv6 Best Practices, Benefits, Transition
    ETSI White Paper No. 35 IPv6 Best Practices, Benefits, Transition Challenges and the Way Forward First edition – August 2020 ISBN No. 979-10-92620-31-1 ETSI 06921 Sophia Antipolis CEDEX, France Tel +33 4 92 94 42 00 [email protected] www.etsi.org Contributing organizations and authors CAICT Zhiruo Liu China Telecom Chongfeng Xie, Cong Li Cisco Patrick Wetterwald, Pascal Thubert, Francois Clad Hewlett-Packard Enterprise Yanick Pouffary Huawei Giuseppe Fioccola, Xipeng Xiao, Georgios Karagiannis, Shucheng(Will) Liu KPN Eduard Metz Luxembourg University Latif Ladid PT Telecom Jose Cananao, Jose Palma Post Luxembourg Sébastien Lourdez Telefonica Luis M. Contreras IPv6 Best Practices, Benefits, Transition Challenges and the Way Forward 2 Contents Contributing organizations and authors 2 Contents 3 Executive Summary 6 1 Background 8 1.1 Why should IPv6 become a priority again? 8 1.2 Goals of this White Paper 9 2 IPv6 progress in the last 5 years 10 2.1 Devices supporting IPv6 10 2.2 Content (web sites, cloud services) supporting IPv6 11 2.3 Networks supporting IPv6 12 2.4 Number of IPv6 users 12 2.5 Amount of IPv6 traffic 13 2.6 IPv6 standardization progress 14 3 IPv6 service design for Mobile, Fixed broadband and enterprises 14 3.1 IPv6 transition solutions from operator perspective 15 3.1.1 For IPv6 introduction 16 3.1.2 For IPv6-only service delivery 17 3.2 IPv6 prefix and address assignment at the CPEs 22 3.2.1 For MBB UEs 23 3.2.2 For FBB RGs 23 3.2.3 For Enterprise CPEs 23 3.3 IPv6 Packet Transport 24 3.4 IPv6 deployment inside enterprise
    [Show full text]
  • Empirical Analysis of Ipv4 and Ipv6 Networks Through Dual-Stack Sites
    information Article Empirical Analysis of IPv4 and IPv6 Networks through Dual-Stack Sites Kwun-Hung Li and Kin-Yeung Wong * School of Science and Technology, The Open University of Hong Kong, Hong Kong, China; [email protected] * Correspondence: [email protected] Abstract: IPv6 is the most recent version of the Internet Protocol (IP), which can solve the problem of IPv4 address exhaustion and allow the growth of the Internet (particularly in the era of the Internet of Things). IPv6 networks have been deployed for more than a decade, and the deployment is still growing every year. This empirical study was conducted from the perspective of end users to evaluate IPv6 and IPv4 performance by sending probing traffic to 1792 dual-stack sites around the world. Connectivity, packet loss, hop count, round-trip time (RTT), and throughput were used as performance metrics. The results show that, compared with IPv4, IPv6 has better connectivity, lower packet loss, and similar hop count. However, compared with IPv4, it has higher latency and lower throughput. We compared our results with previous studies conducted in 2004, 2007, and 2014 to investigate the improvement of IPv6 networks. The results of the past 16 years have shown that the connectivity of IPv6 has increased by 1–4%, and the IPv6 RTT (194.85 ms) has been greatly reduced, but it is still longer than IPv4 (163.72 ms). The throughput of IPv6 is still lower than that of IPv4. Keywords: IPv6; IPv4; network performance; Internet; IoT Citation: Li, K.-H.; Wong, K.-Y. Empirical Analysis of IPv4 and IPv6 1.
    [Show full text]
  • Networking and Internetworking (Basics)
    DTU Informatics Department of Informatics and Mathematical Modelling Networking and Internetworking (Basics) 3.1 Introduction 3.2 Types of Network 3.3 Network Principles DTU Informatics Department of Informatics and Mathematical Modelling Introduction • The networks used in distributed systems are built from a variety of ‣ transmission media (wire, cable, fiber and wireless channels) ‣ hardware devices (routers, switches, bridges, hubs, ...) ‣ software components (protocol stacks, communication handlers and drivers) • The resulting functionality and performance available to distributed system and application programs is affected by all these. 2 DTU Informatics Department of Informatics and Mathematical Modelling Some Terminology • Communication subsystem: the collection of hardware and software components that provide the communication facilities for a distributed system. • Host: computer or other device that use the network for communication purposes. • Node: any computer or switching device attached to a network. • Example: the Internet is a single communication subsystem providing communication between all of the hosts that are connected to it. The Internet is constructed from many subnets. A subnet is a unit of routing; it is a collection of nodes that can all be reached on the same physical network. 3 DTU Informatics Department of Informatics and Mathematical Modelling Network Performance Parameters • The network performance parameters that are of primary interest are those affecting the speed with which individual messages can be transferred between interconnected computers. These parameters are: ‣ Network Latency: the delay that occurs after a send operation is executed before data starts to arrive at the destination computer. ✓Measured as the time required to transfer an empty message ✓Determined primarily by software overheads, routing delays, ..
    [Show full text]
  • Unit 4 Internetworking: Concept, Architecture and Protocols
    - - --- - - UNIT 4 INTERNETWORKING: CONCEPT, ARCHITECTURE AND PROTOCOLS Structure Page Nos. 4.0 Introduction 87 4.1 Objectives 88 4.2 History of Internetworking 88 4.3 Packet Switching 89 4.4 Internetworking Concepts 90 4.5 Internet Addresses 91 4.6 Configuring IP Addresses 92 4.7 TCP/IP 93 4.8 Additional TCP/IP-Related Protocols 94 1 4.9 Application Layer Protocols 4.9.1 File Transfer Protocol 4.9.2 Trivial File Transfer Protocol (TFTP) 4.9.3 TELNET 4.9.4 Remote Login 4.9.5 Electronic Mail (Email) 4.10 World Wide Web .4.11 Domain Name System 4.12 SNMP AND UDP 4.13 Summary 4.15 Further Readings 4.0 INTRODUCTION An internetwork is a collection of packet-switching and broadcast networks, connected by bridges, switches, or routers which are intermediate networking devices, that functions as a single large network. So a11 users and devices can communicate, regardless of the network segment to which they are attached. Figure I illustrates some different kinds of network technologies that can be interconnected by routers and other networking devices to create an internetwork. Figure 1: Internetworking Operating System In this unit we will explain the concepts, architecture and protocols of internetworking. Fundamentals & Networking 4.1 OBJECTIVES After going through this unit you should be able to: define packet switching concept; differentiate between virtual circuit & datagram, and understand the functioning of a large number of protocols. 4.2 HISTORY OF INTERNETWORKING Networking allows computers to share information, applications and even hardware devices. For any two computers to communicate with each other, they must follow a set of rules called protocol.
    [Show full text]