TCP/IP Past, Present, and Future Chapter 6

Learning Objectives Describe the history of TCP/IP Explain how TCP and IP work and how UDP is employed instead of TCP Describe IP addressing and understand how to use it on LANs and WANs Explain new IP version 6 and its intended use continued…

Learning Objectives Discuss how to use application protocols in the TCP/IP suite Understand TCP/IP application protocols Compare TCP/IP to OSI reference model

A Brief History of TCP/IP First attempt to make ARPANET available for universal access (1960s) Network Control Protocol (NCP) Improvements on reliable communication (1970s) Transmission Control Protocol (TCP) Initially designed for point-to-point communications between computers on same network Internet Protocol (IP) Initially developed to enable communications between computers linked to different networks or to WANs

TCP/IP Language computers use to “talk” over Internet Protocol of choice for most medium- and large-sized networks Good choice for most LAN-to-WAN installations Broad acceptance Reliable history Extensive capabilities

Understanding TCP/IP Layered set of protocols similar to, but not identical to, OSI protocol layers Consists of nearly 100 nonproprietary protocols that interconnect computer systems efficiently and reliably Core components Transmission Control Protocol (TCP) User Datagram Protocol (UDP) Internet Protocol (IP)

How TCP Works Establishes communication sessions between networked software application processes Provides reliable end-to-end delivery of data by controlling data flow Sequencing and acknowledging frames

TCP Frame

TCP Source and Destination Ports

TCP Ports

How UDP Works Connectionless alternative to TCP that yields a lower overhead, but is less reliable Relies only on checksum to ensure reliability Handles and transmits data faster; performs no flow control, sequencing, or acknowledgment

UDP Frame

How IP Works Enables packets to reach a destination on a local or remote network by using dotted decimal addressing Used in combination with TCP or UDP

Transport Options Compatible with TCP/IP Ethernet Token ring X.25 FDDI ISDN DSL Frame relay ATM (with conversion)

Basic Functions of IP Data transfer Packet addressing Packet routing Fragmentation Simple detection of packet errors

IP as a Connectionless Protocol Provides network-to-network addressing and routing information Changes size of packets when size varies between networks

TCP/IP Packet Encapsulation

IP Packet

How IP Addressing Works Identifies specific node and network on which it resides Each IP address is unique Dotted decimal notation format 32-bits long; four fields Five classes (Class A through Class E) Reflect size of network and whether packet is unicast or multicast

Role of the Subnet Mask Designated portion of IP address used to: Indicate class of addressing used on a network Divide network into subnetworks to control network traffic

Creating Subnetworks Using a subnet mask to divide a network into smaller networks: Enables Layer 3 devices to ignore traditional address class designations Creates more options for segmenting networks through multiple subnets and additional network addresses Classless Interdomain Routing (CIDR) addressing Newer way to ignore address class designation Provides more IP address options for medium-sized networks

How IPv6 Works Provides logical growth path from IPv4 so that applications and network devices can handle new demands Replaces class-based addresses Designed to be CIDR-compliant Offers options to create distinctions within a single address

Features of IPv6 128-bit address capability Single address associated with multiple interfaces Address autoconfiguration and CIDR addressing 40-byte header instead of IPv4’s 20-byte header New IP extension headers can be implemented for special needs, including more routing and security options

IPv6 Autoconfiguration Techniques Stateful autoconfiguration Employs server management software and leases to automatically assign IP addresses based on parameters set by network administrator Based on Dynamic Host Configuration Protocol (DHCP) Stateless autoconfiguration Network device assigns its own IP address without obtaining it from a server

Types of IPv6 Packets Unicast Anycast Multicast

Fields of the IPv6 Header

IPv6 Extension Headers Hop-by-hop Routing Fragment Authentication Encapsulating security payload Destination options

Example of Extension Headers in an IPv6 Packet

Determining Packet Size Using information acquired from maximum transmission unit (MTU) path discovery, the sending node fragments packets and includes fragment extension header Authentication extension header ensures that the datagram is received s it was sent

Encryption and the IP Packet Using encapsulating security payload extension header Supports key encryption techniques compatible with Data Encryption Standard (DES) security

TCP/IP Application Protocols Telnet File Transfer Protocol (FTP), Trivial File Transfer Protocol (TFTP), and Network File System (NFS) Simple Mail Transfer Protocol (SMTP) Domain Name System (DNS) Dynamic Host Configuration Protocol (DHCP) Address Resolution Protocol (ARP)

Telnet Provides terminal emulation Comes with nearly all vendor implementations of TCP/IP Open standard Supported by wide range of workstations

Telnet Encapsulated in TCP

Telnet Communications Options 7- or 8-bit compatibility Use of different terminal nodes Character echoing at sending and receiving ends Synchronized communications Transmission of character streams or single characters Flow control

FTP Transfers files in bulk data streams Uses two TCP ports (20 and 21) Commonly used on the Internet

Sample FTP Commands

TFTP Designed for transfer of files that enable a diskless workstation to boot Connectionless; runs within UDP Intended for transfer of small files when data transmission errors are not critical and there is no need for security

NFS Transfers information in record streams instead of in bulk file streams Connection-oriented Suited to computers that perform high-volume transaction processing involving records stored within data file of databases

SMTP Designed for exchange of electronic mail between networked systems No login ID/password required for remote system Can send only text files Two parts to messages Address header Message text

SMTP

DNS Converts a computer or domain name to an IP address or converts an IP address to a computer or domain name (resolution) Two parts of computer name, divided by @ Name of computer or node Name of organization (root domain name)

Internet Top Level Domain Conventions

Country Names for Domains

Examples of Proposed TLDs

DNS DNS resolvers and namespaces Use of zones Forward lookup zone Host address (A) resource record Reverse lookup zone Pointer (PTR) resource record

DNS DNS server roles DNS standards Primary DNS server Secondary DNS server Makes sure there is a copy of primary DNS server’s data Enables DNS load balancing Can be spread to different parts of a network DNS standards Service resource record DNS dynamic update protocol

DHCP Automatically leases IP addresses to computers on a network

ARP Enables computer/device to determine MAC address of another computer/device Reverse Address Resolution Protocol (RARP) Used by a network node to determine its own IP address

SNMP Gathers network performance information for troubleshooting Developed in 1980s to provide alternative to OSI standard for network management, Common Management Interface Protocol (CMIP)

Advantages of SNMP Operates independently on the network Does not depend on two-way connection at protocol level with other network entities Can analyze network activity Management functions are carried out at a network management station Lower memory overhead than CMIP

SNMP Node types used with SNMP Management Information Base (MIB) Network management station (NMS) Network agents Management Information Base (MIB) Database of network performance information stored on a network agent for access by a network management station

MIB Variables

Improvements in SNMP v2 Encrypted community name Improved error handling Multiprotocol support Support for IPX and AppleTalk Fast data transmission and ability to retrieve more MIB-II information at one time

Monitoring with SNMP and SNMPv2 Network Associates’ Sniffer software Microsoft’s Network Monitor Remote Network Monitoring (RMON)

Other TCP/IP Application Protocols Archie Bootstrap Protocol (BOOTP) Distance Vector Multicast Routing Protocol (DVMRP) Finger Gopher Hypertext Transfer Protocol (HTTP) Internet Group Management Protocol (IGMP) Multicast Open Shortest Path First Protocol (MOSPF) continued…

Other TCP/IP Application Protocols Open Shortest Path First (OSPF) Ping Real-Time Protocol (RTP) Real-Time Transport Control Protocol (RTCP) Resource Reservation Protocol (RSVP) Routing Information Protocol (RIP) Simple Network Management Protocol (SNMP) Traceroute (tracert)

TCP/IP and OSI Reference Model Compared

Chapter Summary TCP/IP details UDP as alternative to TCP Internals of the TCP and IP packets IP addressing UDP as alternative to TCP When communications acknowledgement is not as important as speed and low overhead IPv6 compared to IPv4 continued…

Chapter Summary Application protocols associated with TCP/IP for: Terminal emulation File transfers E-mail Address naming conversions IP address assignment Network management How TCP/IP relates to OSI reference model