Subject: Current network topology
 
 In fall 1999, we converted our network topology from a flat bus-like
 structure based on copper cables to a switched star-like structure based on
 fiber optic links. All our physically adjacent buildings (NW, EL, CE, and MP)
 got at least one separate fiber feed for each floor (in MP, for each floor
 that the Chemistry Department occupies). JL was connected with one fiber link
 feeding all four floors (as JL is not immediately adjacent to the other
 buildings, we are not at liberty to run multiple fiber pairs between the
 buildings; the JL feed is actually a VPN [virtual private network] going
 through Baker Systems). Until now, most floors were hooked up with 10 MB/s,
 some with 100 MB/s.
 
 We just finished a major network upgrade in NW, CE and MP. The remaining old
 10 MB/s hubs were replaced with 10/100 MB/s switches. All floors in NW, CE
 and MP are now fed with 100 MB/s full duplex. All network jacks on all floors
 in these buildings (except parts of rooms 100 CE and 2060 MP) are 10/100
 MB/s.
 
 Last spring a portion of the network in JL was renovated. A network closet
 was built on the 2nd floor, 10/100 MB/s switches were installed, and 100 JL
 and surrounding offices were converted from coax to twisted pair cabling,
 delivering 10/100 MB/s to every network jack. We are awaiting/hoping for more
 funding to convert the 2nd, 3rd and 4th floor of JL to twisted pair cabling
 later this academic year.
 
 We are in the process of delivering 10/100 MB/s twisted-pair wiring to some
 strategic locations in EL, but this should not be mistaken for a network
 renovation (see below).
 
 All fiber feeds are connected to one central switch (the backbone of the star
 topology); the speed of this switch is currently 15 GB/s. Most of the central
 servers (Unix server, Linux web server, Windows Active Directory servers) are
 directly connected to the backbone switch with 100 MB/s, thus allowing
 maximum throughput and minimum latency between the servers and client
 machines on all floors of all buildings. Some servers, like the Windows file
 server and the backup server, are connected to the backbone switch with 1
 GB/s (1000 MB/s).
 
 As GB-speed equipment becomes more affordable, floors with high traffic will
 be moved from 100 MB/s feeds to 1 GB/s feeds.
 
 The backbone of the star topology is connected to SONNET (the OSU campus
 network) through the departmental firewall. Our connection speed is 100 MB/s
 to SONNET.
 
 All our buildings, except much of JL and almost all of EL, have 10/100BaseT
 (twisted-pair) cabling, allowing you to connect computer equipment to a
 network jack in the wall. Each jack is individually connected to a switch on
 your floor and allows you to use the entire bandwidth of that connection (10
 or 100 MB/s, depending on the network card in your computer). The networks in
 JL and EL are still largely based on coax wires. You connect your computer
 equipment with a T-connector into the coax segment. The coax segment must not
 be interrupted. If you open up a T, or if you remove a piece of the coax
 segment, you interrupt the network on your entire floor or on a major portion
 of your floor. If you have inadvertantly done so once and experienced the
 wrath of your floor, you know that this is "A BAD THING" (tm) to do. Further,
 if you add computers on, say, each side of a large lab, run coax in a zig-zag
 pattern back and forth and thus add another 100 ft or more of coax cable to
 your segment, this may be an "EQUALLY BAD THING" (tm) to do. Coax segments
 have a natural length limit, and extending them significantly beyond that
 limit means asking for trouble. Jim Robbins, in the Electronics Shop, has a
 supply of hubs that can connect a group of 10BaseT computers to the coax
 network. See him if you need this for your network connection.
 
 Even when compared to a 10 MB/s twisted pair network, coax is much much
 slower than twisted-pair because the bandwidth is shared between all
 computers on a segment. EL used to be connected with just one 10 MB/s link.
 It was converted to individual 10 MB/s feeds for each floor in June 2000,
 which resulted in a modest speedup and lower latency. Without a complete
 network renovation, the speed of the network feed to each floor in EL cannot
 be increased. Twisted-pair is faster, much more secure and more reliable, and
 we would like to convert the network as soon as possible. However, it will
 likely still take a while before this expensive network upgrade can be done
 in EL.
 
 If you're unsure about Ethernet cable rules, please consult the Electronics
 Shop. In general, please always consult Jim Robbins before you connect any
 computer to any portion of the network in any of our buildings.