Elements of a Small PC Network LAN

Elements of a Small PC Network • LAN Standards – We will focus on LANs that follow the Ethernet standard (80% do) • Small Ethernet PC networks use only inexpensive UTP wiring (or Coax) • Speeds for NICs and Hubs or Switches – 10 Base-T (10 Mbps, baseband, UTP) – 100 Base-TX (100 Mbps, baseband, UTP) – 1000 Base-T (Gigabit Ethernet) (1 Gbps)

Elements of a Small PC Network • Need a hub or switch to connect the PCs – Connector box with multiple plug-in jacks – Hubs and switches are described later • Each PC needs a network interface card (NIC) – Implements physical and data link layer connection to the LAN • Wire – Business-grade UTP telephone wiring

Elements of a Simple PC Network • Ethernet UTP Wiring – 4 -pair bundle (8 wires) – Each pair is twisted – Terminates in RJ-45 connector • Quality Level – Category 5 – Older categories (3 and 4) exist but are now fairly rare

Elements of a Simple PC Network • Ethernet UTP Wiring – Come pre-cut in many useful lengths (1 m, 25 m, etc. ) with connectors already added to both ends – Can also cut to precise lengths needed and then attach connectors • Must test the wire after cutting it and attaching connectors!

Elements of a Simple PC Network • Plenum Wiring – For wiring run through airways; covering does not give off toxic fumes if it burns • Required if wires are run through air conditioning ducts • Not needed in false ceilings – More expensive but required by law and concern for employee safety

Elements of a Small PC Network • Ethernet Hub Operation – One station transmits a single bit to a hub (physical layer operation) – Hub broadcasts bit to all attached stations – All but the destination PC should ignore the message Hub Bit

Elements of a Small PC Network • Ethernet Hubs – Broadcasting is simple, so – Hubs are inexpensive

Elements of a Small PC Network • Ethernet Hubs Can Create Latency – Only one station may transmit at a time or the signals will collide and be unreadable – Other stations must wait (latency) Must Wait

Elements of a Small PC Network • Ethernet Hubs Can Create Latency – Becomes a problem with 100+ PCs and 10 Mbps hub – 200 PCs is upper limit for tolerable service with a 10 Mbps hub Must Wait

Elements of a Small PC Network • Ethernet Switches – One station transmits a frame to a switch (data link layer operation) – Switch only transmits frame out port of destination PC Switch – No broadcasting out all ports Switch Frame

Elements of a Small PC Network • Ethernet Switches – Multiple conversations can take place simultaneously because there is no broadcasting, which ties up all ports – No wait to transmit; no Latency Switch

Elements of a Simple PC Network • Client PCs – End user’s desktop or notebook PC – Add network interface card (NIC) – With Win 95, Win 98, Win NT, or Win 2000, no extra software is needed – Networks have many client PCs

Elements of a Simple PC Network • Servers – Provide services to client PCs – Usually PCs themselves – Most PC nets have multiple servers – Require a NIC – Require a server operating system (SOS) – Require application software

Elements of a Simple PC Network • Server Operating System (SOS) – Servers need operating systems more reliable than client PC operating systems – Windows NT/2000 Server, Novell Net. Ware, UNIX, LINUX • Application Software – Provides the services offered by the servers – E-mail, word processing, file sharing, etc. – More expensive than the SOS

Elements of a Simple PC Network • Novell Net. Ware SOS – Once dominant, but market share has shrunk – Excellent file and print service – Excellent directory service (later) – Until recently, was not sufficiently robust and scalable for servers other than file servers

Elements of a Small PC Network • Microsoft Windows Server Operating System – More robust than desktop Windows (Win 95, Win 98, etc. ) – All 32 -bit code – Microsoft Windows NT Server before 2000 – Newer Microsoft Windows 2000 Server New • Versions in order of increasing functionality: Windows 2000 Server, Advanced Server, Data. Center Server

Elements of a Small PC Network • Microsoft Windows Server Operating System – Easy to install, learn, and use because resembles desktop Windows – Becoming dominant for small business and small department servers – NT Server has had serious reliability and scalability problems – Windows 2000 Server versions promise to improve reliability and scalability

Elements of a Small PC Network • UNIX – Workstation servers run UNIX – Extremely reliable – Dominate for large enterprise servers

Elements of a Small PC Network • UNIX – Expensive to buy – Must retrain staff or hire UNIX staff – Many versions of UNIX exist • Most run the same application software • However, have different management utilities, etc. , requiring training for each version used – Not for Small PC Networks

Elements of a Small PC Network • LINUX – Version of UNIX – Runs on PCs for low cost – Available free • But usually pay around $50 for packaged version – Reliable like other UNIX versions – Open Source: Many people are developing tools to add to the LINUX core

Elements of a Small PC Network • LINUX – Available in Distributions New • A distribution has the LINUX kernel plus other programs • Available on CD-ROM or by downloading • Distributions from different LINUX vendors differ in the specific programs included • Differences make selection, implementation difficult

Elements of a Small PC Network • LINUX – Requires Extensive Labor to Set Up, Maintain – Device driver software often is lacking for printers, disk drives, and other devices – Requires more training because it is UNIX – Better distributions and support coming?