Switches Routers PCs Networking 101 Introduction to Ethernet networking basics; Network types, components, configurations Servers Hubs Protocols Cat-5 UTP NICs Page 1 July 28, 2000
Network Types LAN Local Area Network Connects users in the same building MAN Metropolitan Area Network Connects sites in and around a city Basically a WAN within a city WAN Wide Area Network Connects sites around the country and world Typically is a low speed link (due to cost) Building Backbone Connects LANs within a building May use optical fibre to connect buildings (high speed links) Campus Backbone Connects building LANs May use optical fibre to connect buildings (high speed links) Enterprise Network Connects many (or all) of the networks on this page Page 2 July 28, 2000
Network Components Client (user) system/workstation (including local OS and NOS (Network Operating System) Network Interface Card (NIC) and associated drivers. Each has a unique MAC address Cabling (typically Cat-5 UTP for data transfer rates up to 100Mbps) Servers (including networking software) for applications, fileserving, printing, etc. Connectivity devices (switches, hubs, routers, patch panels) Page 3 July 28, 2000
What is a NOS? Network Operating System Software that makes LAN and WAN communications easy Allows users to interface to the LAN transparently Provides services such as: file, print, email, database, security, etc. The NOS determines if data is to be used locally or redirected (through the NIC) to the network (and likewise, if resources are local or on the network) Provides client software allowing access to servers on the network NOS examples UNIX Novell Netware Windows (NT) MacOS Page 4 July 28, 2000
LAN Types Client/servers Clients File server Print server Peer-to-peer network Distributed management All workstations share their resources with other workstations Typically small (each workstation has performance impacts due to servicing each other s requests over the network) Client/Server Network Centralized management Characteristics: Servers are typically configured for specific needs Servers service requests from clients; clients do not service each other Page 5 July 28, 2000
File Service File Request Copy of File Provided File services are provided by the NOS File services allow users to access files on remote (networked) systems as if they were local Fileservers: Contain data files & permissions for users and groups; Provides shared storage for users Provides file mapping schemes to provide virtual files ; file are made to look like the user s native file system Provides file security Page 6 July 28, 2000
A Typical Network WAN WAN To other sites & networks LAN Router Routers connect networks, not devices they provide logical segmentation, connection of distant sites, and can improve management, security and performance in large networks. Provides logical segmentation Switch Switches also connect a number of devices but they connect only two devices in a transaction, and isolate traffic (allowing better use of network bandwidth). Provides physical segmentation Hubs connect a number of devices they are essentially repeaters (all devices connected to a hub see all of the traffic). Provides physical connectivity (Sales Dept.) Traffic Segmented (Engr.Dept.) Collision Domain A Collision Domain B Page 7 July 28, 2000
Which Cables to Use Crossover Cable Straight-Through Cable Crossover Cable Crossover Cable Switch Straight-Through Cable Straight-Through Cable Two device types DTE Data Terminal Equipment PCs, Terminals, End user devices DCE Data Communications Equipment Hubs, Switches, Modems Straight-through cables are used when connecting DCE to DTE devices Use crossover cables for connecting like devices DTE-DTE or DCE-DCE The exception: Use straight-through cables when connecting like devices through an uplink port Page 8 July 28, 2000
Building a Network (Sales Dept.) Switch 10Mbps Ethernet 5-4-3 Rule Reduces collisions In a collision domain you can have 5 Ethernet segments with 4 hubs between 2 stations Only 3 of these segments can have users Switches or routers restart the rule by creating a new collision domain 100Mbps Ethernet 2-1 Rule Hubs must be connected to an internetworking device (switches or routers) Page 9 July 28, 2000
Stacked Protocols A protocol is a set of rules that defines how computers (or other devices) communicate and exchange information. These are common to most all networking devices SMB, CIFS, NFS TCP/IP Ethernet These protocols are the focus of NAS SMB/CIFS: Windows NFS: Unix/Linux IPX/SPX: Novell AppleShare: Apple Networking devices (NAS in particular) all use these protocols to do their jobs Page 10 July 28, 2000
Ethernet Overview Multiple data transfer speeds 10Mbps, 100Mbps ( Fast Ethernet ), 1000Mbps ( Gigabit Ethernet ) Throughput is significantly lower than these speeds 10BaseT is the most common cabling option UTP (unshielded twisted pair) category 3 or better (typically cat 5) Hubs and NICs connect devices RJ-45 connectors are used on cables and devices If a cable is damaged, only that link is affected Typically uses wall jacks and patch panels to simplify network changes Ethernet II frames are the most common format for packaging data Ethernet can also be referred to as the CSMA/CD protocol Carrier Sense Multiple Access / Collision Detect There is no arbitration by a device to gain access to the bus before transmitting data All devices attempt to transmit; if a collision is detected, all devices back off for a random delay time and attempt to retransmit the frame Using switches in a network isolates traffic, and as such, reduces the number of collisions Page 11 July 28, 2000
TCP/IP Overview Transaction Control Protocol / Internet Protocol Provides a common transport that allows different types of devices to communicate over a network to share files and applications Provides networking services Dominant communications protocol today TCP/IP has several layers Network Access: Provides physical delivery of packets Internet: Provides addressing and routing information Subnetting occurs here A subnet is a network that is a portion of a larger network, connected by routers Host-to-Host :Provides (2) services for the reliability and session aspects of transmission TCP: reliable data transfers with assurance that data was delivered correctly UDP: unreliable data transfers with little/no means to insure data delivery Process: Application support (telnet, smtp, http, ftp, etc.) Page 12 July 28, 2000
Other Important Networking Stuff DHCP Server A Dynamic Host Configuration Protocol A server that can assign IP addresses to client PC s or servers on a network DHCP Client A client that can be assigned an IP address by a DHCP server DNS A Domain Name Server Resolves host names to their equivalent IP addresses so that IP traffic can be transported to the correct destination WINS Windows Internet Name Service Resolves computer names to an IP address Workgroup A group of computers on a network that accesses the same resources Domain Typically an intranet, which may contain many workgroups Page 13 July 28, 2000