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 –10Base-T (10 Mbps, baseband, UTP) –100Base-TX (100 Mbps, baseband, UTP) –1000Base-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, 2 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 –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 Win95, Win98, 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 NetWare, UNIX, LINUX Application Software –Provides the services offered by the servers – , word processing, file sharing, etc. –More expensive than the SOS

Elements of a Simple PC Network Novell NetWare 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 Versions in order of increasing functionality: Windows 2000 Server, Advanced Server, DataCenter Server New

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 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 New

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?