Chapter 15 Network Hardware Unix System Administration

If VirtualRatings.Com Had Student Ratings, You’d Get a 10 Network technologies & topologies –Ethernet - bus, star –Token-Ring –FDDI - ring –ATM - star Networking Devices –Hubs –Bridges/switches –Routers

You’ve Got Some Nice Toplogies Ethernet –Bus technology –Can be wired in a bus or physical star topology –The Polite Dinner Party - CSMA/CD Carrier sense Multiple access Collision detection –Hubs, switches, bridges and routers

Wirez Wire Thicknet –10Base ohm RG-11 –Vampire Taps connect drop cable to thicknet –Max length = 117m with 2.5m between devices Thinnet –10Base ohm RG-58 –BNC T connectors –Max length = 185m

Twisting The Au Pairs Star configs using hubs or switches Wires are twisted to compensate for cross- talk - Don’t use a regular phone cable Two pairs (4-wires) are used even though four pair cable is usually installed RJ-45 connector pins 1,2,3 & 6 are used Cabling is rated in levels –Level III (3) is for up to 10Mbps –Level V is for up to 100Mbps

How About More Fiber In Your Diet? Fiber cable is basically a piece of glass covered with a reflective cladding Fiber devices are always configured in a star (point-to-point) Fiber is either multi-mode or single-mode I wouldn’t waste fiber on anything less than 100Mbps. Currently Gigabit Ethernet is only available using fiber. SX-short wave, LX-long wave

Do It Yourself Laser Eye Surgery Fiber-optic safety –Be Careful not to stick yourself with a broken fiber –Two types of signal source, LED and LASER –NEVER look into a fiber cable if you don’t know what’s connected to the other end

Is That a Token In Your Ring, or Are You Just Happy To See Me? Token-Ring use a token passing scheme that guarantees each device gets a chance to transmit data FDDI works similar to token-ring but uses fiber-optics in a 100Mbps dual counter- rotating ring configuration –Good at surviving a single ring cut –Expensive

ATM, Your PIN # Please Asynchronous Transfer Mode For voice, video and data transmissions Uses 53-byte cells instead of packets in a switching network similar to a telephone system. Never really took off in a LAN environment but is very popular in the WAN or backbone Feature QoS and RSVP Big learning curve over Ethernet technologies

Hubs and Switches and Routers, Oh My! Hubs –Basically a multi-port repeater –Ethernet limits repeaters to 4 per segment –Each hub counts as a single repeater –Modern hubs usually have a way to connect them without incurring a repeater hop –Hubs being replaced by inexpensive switches –I wouldn’t suggest a hub except in the most trivial network setup

Bridges, Switches. What’s The Difference? Bridge connects multiple segments of a network together Bridges can also connect differing topologies (e.g. token-ring & Ethernet) Switches are fast bridges Bridges and switches work at layer 2 of the OSI model (data link) which means decisions are based on MAC addresses

Routers Schmouters Routers connect networks/IP subnetworks together. Routers work at Layer 3 of the OSI model (Network) Routers are smart and can make decisions based on IP (or IPX) addresses and can filter based on TCP/UDP port numbers

Trans-topological Devices Layer 3 Switches –a.k.a. fast routers –Routes IP/IPX/Appletalk only –VLANS (port, protocol or network-based) Layer 4 Switches/Routers –Makes decisions based on protocol content, e.g. URL

If You Slept Through Everything Else, Pay Attention Now

10- Pure Perfection!.. When would you pick a switch over a bridge? When would you pick fiber over copper? When would you want to use ATM’s RSVP and QoS?