Chapter 4 Network Layer
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15-744: Computer Networking Multicast Routing Example Applications Overview
Multicast Routing • Unicast: one source to one destination • Multicast: one source to many destinations 15-744: Computer Networking • Two main functions: • Efficient data distribution • Logical naming of a group L-20 Multicast 2 Example Applications Overview • Broadcast audio/video • IP Multicast Service Basics • Push-based systems • Software distribution • Multicast Routing Basics • Web-cache updates • Teleconferencing (audio, video, shared • Overlay Multicast whiteboard, text editor) • Multi-player games • Reliability • Server/service location • Other distributed applications • Congestion Control 3 4 1 IP Multicast Architecture Multicast – Efficient Data Distribution Src Src Service model Hosts Host-to-router protocol (IGMP) Routers Multicast routing protocols (various) 5 6 Multicast Router Responsibilities IP Multicast Service Model (rfc1112) • Learn of the existence of multicast groups • Each group identified by a single IP address (through advertisement) • Groups may be of any size • Identify links with group members • Members of groups may be located anywhere in the Internet • Establish state to route packets • Members of groups can join and leave at will • Replicate packets on appropriate interfaces • Senders need not be members • Routing entry: • Group membership not known explicitly • Analogy: Src, incoming interface List of outgoing interfaces • Each multicast address is like a radio frequency, on which anyone can transmit, and to which anyone can tune-in. 7 8 2 IP Multicast Addresses Multicast Scope Control – Small TTLs • Class -
A Comprehensive Study of Routing Protocols Performance with Topological Changes in the Networks Mohsin Masood Mohamed Abuhelala Prof
A comprehensive study of Routing Protocols Performance with Topological Changes in the Networks Mohsin Masood Mohamed Abuhelala Prof. Ivan Glesk Electronics & Electrical Electronics & Electrical Electronics & Electrical Engineering Department Engineering Department Engineering Department University of Strathclyde University of Strathclyde University of Strathclyde Glasgow, Scotland, UK Glasgow, Scotland, UK Glasgow, Scotland, UK mohsin.masood mohamed.abuhelala ivan.glesk @strath.ac.uk @strath.ac.uk @strath.ac.uk ABSTRACT different topologies and compare routing protocols, but no In the modern communication networks, where increasing work has been considered about the changing user demands and advance applications become a functionality of these routing protocols with the topology challenging task for handling user traffic. Routing with real-time network limitations. such as topological protocols have got a significant role not only to route user change, network congestions, and so on. Hence without data across the network but also to reduce congestion with considering the topology with different network scenarios less complexity. Dynamic routing protocols such as one cannot fully understand and make right comparison OSPF, RIP and EIGRP were introduced to handle among any routing protocols. different networks with various traffic environments. Each This paper will give a comprehensive literature review of of these protocols has its own routing process which each routing protocol. Such as how each protocol (OSPF, makes it different and versatile from the other. The paper RIP or EIGRP) does convergence activity with any change will focus on presenting the routing process of each in the network. Two experiments are conducted that are protocol and will compare its performance with the other. -
Solutions to Chapter 2
CS413 Computer Networks ASN 4 Solutions Solutions to Assignment #4 3. What difference does it make to the network layer if the underlying data link layer provides a connection-oriented service versus a connectionless service? [4 marks] Solution: If the data link layer provides a connection-oriented service to the network layer, then the network layer must precede all transfer of information with a connection setup procedure (2). If the connection-oriented service includes assurances that frames of information are transferred correctly and in sequence by the data link layer, the network layer can then assume that the packets it sends to its neighbor traverse an error-free pipe. On the other hand, if the data link layer is connectionless, then each frame is sent independently through the data link, probably in unconfirmed manner (without acknowledgments or retransmissions). In this case the network layer cannot make assumptions about the sequencing or correctness of the packets it exchanges with its neighbors (2). The Ethernet local area network provides an example of connectionless transfer of data link frames. The transfer of frames using "Type 2" service in Logical Link Control (discussed in Chapter 6) provides a connection-oriented data link control example. 4. Suppose transmission channels become virtually error-free. Is the data link layer still needed? [2 marks – 1 for the answer and 1 for explanation] Solution: The data link layer is still needed(1) for framing the data and for flow control over the transmission channel. In a multiple access medium such as a LAN, the data link layer is required to coordinate access to the shared medium among the multiple users (1). -
IP Multicast Routing Technology Overview
IP Multicast Routing Technology Overview • Information About IP Multicast Technology, on page 1 • Additional References for IP Multicast, on page 15 Information About IP Multicast Technology This section provides information about IP multicast technology. About IP Multicast Controlling the transmission rate to a multicast group is not supported. At one end of the IP communication spectrum is IP unicast, where a source IP host sends packets to a specific destination IP host. In IP unicast, the destination address in the IP packet is the address of a single, unique host in the IP network. These IP packets are forwarded across the network from the source to the destination host by devices. At each point on the path between source and destination, a device uses a unicast routing table to make unicast forwarding decisions, based on the IP destination address in the packet. At the other end of the IP communication spectrum is an IP broadcast, where a source host sends packets to all hosts on a network segment. The destination address of an IP broadcast packet has the host portion of the destination IP address set to all ones and the network portion set to the address of the subnet. IP hosts, including devices, understand that packets, which contain an IP broadcast address as the destination address, are addressed to all IP hosts on the subnet. Unless specifically configured otherwise, devices do not forward IP broadcast packets, so IP broadcast communication is normally limited to a local subnet. IP multicasting falls between IP unicast and IP broadcast communication. IP multicast communication enables a host to send IP packets to a group of hosts anywhere within the IP network. -
OSI Model and Network Protocols
CHAPTER4 FOUR OSI Model and Network Protocols Objectives 1.1 Explain the function of common networking protocols . TCP . FTP . UDP . TCP/IP suite . DHCP . TFTP . DNS . HTTP(S) . ARP . SIP (VoIP) . RTP (VoIP) . SSH . POP3 . NTP . IMAP4 . Telnet . SMTP . SNMP2/3 . ICMP . IGMP . TLS 134 Chapter 4: OSI Model and Network Protocols 4.1 Explain the function of each layer of the OSI model . Layer 1 – physical . Layer 2 – data link . Layer 3 – network . Layer 4 – transport . Layer 5 – session . Layer 6 – presentation . Layer 7 – application What You Need To Know . Identify the seven layers of the OSI model. Identify the function of each layer of the OSI model. Identify the layer at which networking devices function. Identify the function of various networking protocols. Introduction One of the most important networking concepts to understand is the Open Systems Interconnect (OSI) reference model. This conceptual model, created by the International Organization for Standardization (ISO) in 1978 and revised in 1984, describes a network architecture that allows data to be passed between computer systems. This chapter looks at the OSI model and describes how it relates to real-world networking. It also examines how common network devices relate to the OSI model. Even though the OSI model is conceptual, an appreciation of its purpose and function can help you better understand how protocol suites and network architectures work in practical applications. The OSI Seven-Layer Model As shown in Figure 4.1, the OSI reference model is built, bottom to top, in the following order: physical, data link, network, transport, session, presentation, and application. -
Medium Access Control Layer
Telematics Chapter 5: Medium Access Control Sublayer User Server watching with video Beispielbildvideo clip clips Application Layer Application Layer Presentation Layer Presentation Layer Session Layer Session Layer Transport Layer Transport Layer Network Layer Network Layer Network Layer Univ.-Prof. Dr.-Ing. Jochen H. Schiller Data Link Layer Data Link Layer Data Link Layer Computer Systems and Telematics (CST) Physical Layer Physical Layer Physical Layer Institute of Computer Science Freie Universität Berlin http://cst.mi.fu-berlin.de Contents ● Design Issues ● Metropolitan Area Networks ● Network Topologies (MAN) ● The Channel Allocation Problem ● Wide Area Networks (WAN) ● Multiple Access Protocols ● Frame Relay (historical) ● Ethernet ● ATM ● IEEE 802.2 – Logical Link Control ● SDH ● Token Bus (historical) ● Network Infrastructure ● Token Ring (historical) ● Virtual LANs ● Fiber Distributed Data Interface ● Structured Cabling Univ.-Prof. Dr.-Ing. Jochen H. Schiller ▪ cst.mi.fu-berlin.de ▪ Telematics ▪ Chapter 5: Medium Access Control Sublayer 5.2 Design Issues Univ.-Prof. Dr.-Ing. Jochen H. Schiller ▪ cst.mi.fu-berlin.de ▪ Telematics ▪ Chapter 5: Medium Access Control Sublayer 5.3 Design Issues ● Two kinds of connections in networks ● Point-to-point connections OSI Reference Model ● Broadcast (Multi-access channel, Application Layer Random access channel) Presentation Layer ● In a network with broadcast Session Layer connections ● Who gets the channel? Transport Layer Network Layer ● Protocols used to determine who gets next access to the channel Data Link Layer ● Medium Access Control (MAC) sublayer Physical Layer Univ.-Prof. Dr.-Ing. Jochen H. Schiller ▪ cst.mi.fu-berlin.de ▪ Telematics ▪ Chapter 5: Medium Access Control Sublayer 5.4 Network Types for the Local Range ● LLC layer: uniform interface and same frame format to upper layers ● MAC layer: defines medium access .. -
WAN-LAN PIM Multicast Routing and LAN IGMP FEATURE OVERVIEW and CONFIGURATION GUIDE
Technical Guide WAN-LAN PIM Multicast Routing and LAN IGMP FEATURE OVERVIEW AND CONFIGURATION GUIDE Introduction This guide describes WAN-LAN PIM Multicast Routing and IGMP on the LAN and how to configure WAN-LAN PIM multicast routing and LAN IGMP snooping. The AlliedTelesis Next Generation Firewalls (NGFWs) can perform routing of IPv4 and IPv6 multicast, using PIM-SM and PIM-DM. Also, switching interfaces of the NGFWs are IGMP aware, and will only forward multicast steams to these switch ports that have received reports. IGMP snooping allows a device to only forward multicast streams to the links on which they have been requested. PIM Sparse mode requires specific designated routers to receive notification of all streams destined to specific ranges of multicast addresses. When a router needs to get hold of a given group, it sends a request to the designated Rendezvous Point for that group. If there is a source in the network that is transmitting a stream to this group, then the Rendezvous Point will be receiving it, and will forward it to the requesting router. C613-22042-00 REV A alliedtelesis.com x Products and software version that apply to this guide Contents Introduction.............................................................................................................................................................................1 Products and software version that apply to this guide .......................................................................2 Configuring WAN-LAN PIM Multicast Routing and LAN IGMP Snooping........................................3 -
The OSI Model: Understanding the Seven Layers of Computer Networks
Expert Reference Series of White Papers The OSI Model: Understanding the Seven Layers of Computer Networks 1-800-COURSES www.globalknowledge.com The OSI Model: Understanding the Seven Layers of Computer Networks Paul Simoneau, Global Knowledge Course Director, Network+, CCNA, CTP Introduction The Open Systems Interconnection (OSI) model is a reference tool for understanding data communications between any two networked systems. It divides the communications processes into seven layers. Each layer both performs specific functions to support the layers above it and offers services to the layers below it. The three lowest layers focus on passing traffic through the network to an end system. The top four layers come into play in the end system to complete the process. This white paper will provide you with an understanding of each of the seven layers, including their functions and their relationships to each other. This will provide you with an overview of the network process, which can then act as a framework for understanding the details of computer networking. Since the discussion of networking often includes talk of “extra layers”, this paper will address these unofficial layers as well. Finally, this paper will draw comparisons between the theoretical OSI model and the functional TCP/IP model. Although TCP/IP has been used for network communications before the adoption of the OSI model, it supports the same functions and features in a differently layered arrangement. An Overview of the OSI Model Copyright ©2006 Global Knowledge Training LLC. All rights reserved. Page 2 A networking model offers a generic means to separate computer networking functions into multiple layers. -
Routing Review Autonomous System Concept
Routing Review Autonomous System Concept • Term Autonomous System (AS) to specify groups of routers • One can think of an AS as a contiguous set of networks and routers all under control of one administrative authority – For example, an AS can correspond to an ISP, an entire corporation, or a university – Alternatively, a large organization with multiple sites may choose to define one AS for each site – In particular, each ISP is usually a single AS, but it is possible for a large ISP to divide itself into multiple ASs • The choice of AS size can be made for – economic, technical, or administrative reasons The Two Types of Internet Routing Protocols • All Internet routing protocols are divided into two major categories: – Interior Gateway Protocols (IGPs) – Exterior Gateway Protocols (EGPs) • After defining the two categories – we will examine a set of example routing protocols that illustrate each category • Interior Gateway Protocols (IGPs) • Exterior Gateway Protocols (EGPs) The Two Types of Internet Routing Protocols Interior Gateway Protocols (IGPs) • Routers within an AS use an IGP exchange routing information • Several IGPs are available – each AS is free to choose its own IGP • Usually, an IGP is easy to install and operate • IGP may limit the size or routing complexity of an AS The Two Types of Internet Routing Protocols Exterior Gateway Protocols (EGPs) • A router in one AS uses an EGP to exchange routing information with a router in another AS • EGPs are more complex to install and operate than IGPs – but EGPs offer more flexibility -
Ipv6 Addresses
56982_CH04II 12/12/97 3:34 PM Page 57 CHAPTER 44 IPv6 Addresses As we already saw in Chapter 1 (Section 1.2.1), the main innovation of IPv6 addresses lies in their size: 128 bits! With 128 bits, 2128 addresses are available, which is ap- proximately 1038 addresses or, more exactly, 340.282.366.920.938.463.463.374.607.431.768.211.456 addresses1. If we estimate that the earth’s surface is 511.263.971.197.990 square meters, the result is that 655.570.793.348.866.943.898.599 IPv6 addresses will be available for each square meter of earth’s surface—a number that would be sufficient considering future colo- nization of other celestial bodies! On this subject, we suggest that people seeking good hu- mor read RFC 1607, “A View From The 21st Century,” 2 which presents a “retrospective” analysis written between 2020 and 2023 on choices made by the IPv6 protocol de- signers. 56982_CH04II 12/12/97 3:34 PM Page 58 58 Chapter Four 4.1 The Addressing Space IPv6 designers decided to subdivide the IPv6 addressing space on the ba- sis of the value assumed by leading bits in the address; the variable-length field comprising these leading bits is called the Format Prefix (FP)3. The allocation scheme adopted is shown in Table 4-1. Table 4-1 Allocation Prefix (binary) Fraction of Address Space Allocation of the Reserved 0000 0000 1/256 IPv6 addressing space Unassigned 0000 0001 1/256 Reserved for NSAP 0000 001 1/128 addresses Reserved for IPX 0000 010 1/128 addresses Unassigned 0000 011 1/128 Unassigned 0000 1 1/32 Unassigned 0001 1/16 Aggregatable global 001 -
Unicast Multicast IP Multicast Introduction
Outline 11: ❒ IP Multicast ❒ Multicast routing IP Multicast ❍ Design choices ❍ Distance Vector Multicast Routing Protocol (DVMRP) Last Modified: ❍ Core Based Trees (CBT) ❍ Protocol Independent Multicast (PIM) 4/9/2003 1:15:00 PM ❍ Border Gateway Multicast Protocol (BGMP) ❒ Issues in IP Multicast Deplyment Based on slides by Gordon Chaffee Berkeley Multimedia Research Center URL: http://bmrc.berkeley.edu/people/chaffee 4: Network Layer 4a-1 4: Network Layer 4a-2 What is multicast? Unicast ❒ ❒ 1 to N communication Problem Sender ❍ ❒ Nandwidth-conserving technology that Sending same data to reduces traffic by simultaneously many receivers via unicast is inefficient delivering a single stream of information to R multiple recipients ❒ Example ❒ Examples of Multicast ❍ Popular WWW sites ❍ Network hardware efficiently supports become serious multicast transport bottlenecks • Example: Ethernet allows one packet to be received by many hosts ❍ Many different protocols and service models • Examples: IETF IP Multicast, ATM Multipoint 4: Network Layer 4a-3 4: Network Layer 4a-4 Multicast IP Multicast Introduction ❒ Efficient one to many Sender ❒ Efficient one to many data distribution data distribution ❍ Tree style data distribution ❍ Packets traverse network links only once R ❒ Location independent addressing ❍ IP address per multicast group ❒ Receiver oriented service model ❍ Applications can join and leave multicast groups ❍ Senders do not know who is listening ❍ Similar to television model ❍ Contrasts with telephone network, ATM 4: Network Layer -
Introduction to IP Multicast Routing
Introduction to IP Multicast Routing by Chuck Semeria and Tom Maufer Abstract The first part of this paper describes the benefits of multicasting, the Multicast Backbone (MBONE), Class D addressing, and the operation of the Internet Group Management Protocol (IGMP). The second section explores a number of different algorithms that may potentially be employed by multicast routing protocols: - Flooding - Spanning Trees - Reverse Path Broadcasting (RPB) - Truncated Reverse Path Broadcasting (TRPB) - Reverse Path Multicasting (RPM) - Core-Based Trees The third part contains the main body of the paper. It describes how the previous algorithms are implemented in multicast routing protocols available today. - Distance Vector Multicast Routing Protocol (DVMRP) - Multicast OSPF (MOSPF) - Protocol-Independent Multicast (PIM) Introduction There are three fundamental types of IPv4 addresses: unicast, broadcast, and multicast. A unicast address is designed to transmit a packet to a single destination. A broadcast address is used to send a datagram to an entire subnetwork. A multicast address is designed to enable the delivery of datagrams to a set of hosts that have been configured as members of a multicast group in various scattered subnetworks. Multicasting is not connection oriented. A multicast datagram is delivered to destination group members with the same “best-effort” reliability as a standard unicast IP datagram. This means that a multicast datagram is not guaranteed to reach all members of the group, or arrive in the same order relative to the transmission of other packets. The only difference between a multicast IP packet and a unicast IP packet is the presence of a “group address” in the Destination Address field of the IP header.