– The Internet is based on IP addresses
– Data link protocols (Ethernet, FDDI, ATM) may have
different (MAC) addresses
• The ARP and RARP protocols perform the translation
between IP addresses and MAC layer addresses
• We will discuss ARP for broadcast LANs, particularly Ethernet
With an expanded discussion of network protocols and 45 completely new scenarios, this extensively revised second edition of the best-selling Practical Packet Analysis will teach you how to make sense of your PCAP data. You'll find new sections on troubleshooting slow networks and packet analysis for security to help you better understand how modern exploits and malware behave at the packet level. Add to this a thorough introduction to the TCP/IP network stack and you're on your way to packet analysis proficiency.
General Packet Radio Service (GPRS)
Packet data transmission has already been standardized in GSM phase 2, offering access to the Packet Switched Public Data Network (PSPDN); see Sections 9.5.3 and 9.6.2. However, on the air interface such access occupies a complete circuit switched traf®c channel for the entire call period. In case of bursty traf®c (e.g. Internet traf®c), such access leads to a highly inef®cient resource utilization. It is obvious that in this case, packet switched bearer services result in a much better utilization of the traf®c channels.
This brief guide aims at explaining the basic steps for getting started with GPRS. It supposes you are a bit familiar with GPRS concepts, like network attachment, session or PDP context.
This guide is not intended to give full details about how GPRS works, all GPRS-specific AT commands (check out the GPRS AT command manual).
By default depending on the firmware version, the MS starts up either in class CG (i.e. in GPRS mode and not in GSM mode) or in class B.
What Is VoIP? Real-time Versus Nonreal-time Data Why Change to VoIP? The Business Case VoIP and FCC Regulation 911 A Note on Power General VoIP Topologies Power over Ethernet PoE Basic Operation VoIP Protocols Signaling Protocols Transport Protocol VoIP Basic Operation Performance Unified Communications Summary Standards and Reading Review Questions Review Question Answers Lab Activities Activity 1—Review of the Standards Activity 2—Download Wireshark and the Capture Files for This Chapter Activity 3—Examine VoIP Offerings in Your Area Activity...
Congestion occurs when the number of packets being transmitted through the network approaches the packet handling capacity of the network
Congestion control aims to keep number of packets below level at which performance falls off dramatically
Data network is a network of queues
Generally 80% utilization is critical
Finite queues mean data may be lost
RIP version 2 is not a new protocol—it is RIP Version 1 with some additional fields in the route update packet, key among them being subnet mask information in each route entry. The underlying DV algorithms in RIP-2 are identical to those in RIP-1, implying that RIP-2 still suffers from convergence problems and the maximum hop- count limit of 16 hops.
This chapter describe the primary functions and features of a router, explain how routers use information in data packets to make forwarding decisions in a small to medium-sized business network, explain the encapsulation and de-encapsulation process used by routers when switching packets between interfaces,...
Chapter 20 - Network layer: internet protocol. This chapter is devoted to the main protocol at the network layer that supervises and controls the delivery of packets from the source to destination. This protocol is called the Internet Protocol or IP.
The H.323 standard is a cornerstone technology for the transmission of real-time
audio, video, and data communications over packet-based networks. It specifies
the components, protocols, and procedures providing multimedia
communication over packet-based networks (see Figure 1). Packet-based
networks include IP–based (including the Internet) or Internet packet exchange
(IPX)–based local-area networks (LANs), enterprise networks (ENs),
metropolitan-area networks (MANs), and wide-area networks (WANs). H.
Describe the basic purpose of a router
– Computers that specialize in sending packets over the data
– They are responsible for interconnecting networks by selecting
the best path for a packet to travel and forwarding packets to
Routers are the network center
– Routers generally have 2 connections:
• WAN connection (Connection to ISP)
• LAN connection
Data Link Layer. Learning Objectives
Upon completion of this chapter, you will be able to:
Explain the role of Data Link layer protocols in data transmission.
Describe how the Data Link layer prepares data for transmission on network media.
Describe the different types of media access control methods.
Identify several common logical network topologies and describe how the logical topology determines the media access control method for that network.
Explain the purpose of encapsulating packets into frames to facilitate media access. ...
Multicast is UDP Based!!!
Best Effort Delivery: Drops are to be expected. Multicast applications should not expect reliable delivery of data and should be designed accordingly. Reliable Multicast is still an area for much research. Expect to see more developments in this area.
No Congestion Avoidance: Lack of TCP windowing and “flow-control” mechanisms can result in network congestion. If possible, Multicast applications should attempt to detect and avoid congestion conditions.
Duplicates: Some multicast protocol mechanisms (e.g.
Networking Standards and the OSI Model
Identify organizations that set standards for networking.
Describe the purpose of the OSI Model and each of its layers
Explain specific functions belonging to each OSI Model layer
Understand how two network nodes communicate through the OSI model
Discuss the structure and purpose of data packets and frames.
Describe the two types of addressing covered by the OSI Model.
Used to communicate IP status and error messages between hosts and routers
Uses IP to route its messages between hosts
Must be implemented with IP
remember, IP is just a packet delivery system
transmits and routes datagrams from sources to destinations through a series of interconnected networks
it has a checksum in the IP header to detect lost bits
no error detection on the datagram payload though
but has no native mechanism for source host notification
This is where ICMP comes in
its used to report IP errors to the source host
ICMP data is carried as the payload of an IP datagram
Chapter 10 - TCP/IP Applications. Chapter summary: Bridges selectively relay packets between network segments, depending on their data-link layer destination addresses; bridges maintain a single broadcast domain and create separate collision domains; switches improve on the function of bridges by forwarding packets only to their destination systems;...and other contents.
The Internet Protocol (IP) is a routed protocol that is used to transmit data in
packets. It uses the best-effort delivery for individual packets without any flow
control. Transmission Control Protocol (TCP) is used with IP to provide a
Asynchronous Transfer Mode (ATM), on the other hand, provides connections
between endpoints in the ATM network. The connections are called virtual circuits
IP’s default best effort service can be supplemented by differentiated quality of
service based on IP precedence or DSCP marking.
Một nút gởi, một nút nhận, một kết nối: không cần media access control, không cần địa chỉ/e.g., dialup link, ADSL, ISDN. Một số giao thức DLC điểm - điểm: PPP( point- to- point protocol) HDLC : High level data link control .Packet framing: hỗ trợ nhiều giao thức, dồn kênh/phan kênh. Bit transparency .Error detection( không cần correction).Connection liveness
ARP is used as a tool for confirming that a computer is successfully resolving network Layer 3 addresses to Media Access Control (MAC) Layer 2 addresses. The TCP/IP network protocol relies on IP addresses like 192.168.14.211 to identify individual devices and to assist in navigating data packets between networks. While the IP address is essential to move data from one LAN to another, it cannot deliver the data in the destination LAN by itself. Local network protocols, like Ethernet or Token Ring, use the MAC, or Layer 2, address to identify local devices and deliver all data. A computer MAC...
The Internet Protocol (IP) is the protocol by which information is sent from one computer to another on
the Internet. Each computer on the Internet has at least one address that uniquely identifies it from all other
computers on the Internet. When you send or receive data (for example, an e-mail note or a web page), the
message gets divided into little chunks called packets.