Subject: Current network topology
 
 About a year ago, we started to convert 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) have at least one separate fiber feed for each floor (in MP, for
 each floor that the Chemistry Department occupies). JL is connected with one
 fiber link feeding all four floors. Most floors are hooked up with 10 MB/s,
 some with 100 MB/s. Every year, some of the 10 MB/s hubs are replaced with
 10/100 MB/s switches; these upgrades are contingent on funding. All fiber
 feeds are connected to one central switch (the backbone of the star
 topology); the speed of this switch is currently 1 GB/s (scheduled to be
 upgraded). All central servers (Unix server, NT 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.
 
 The backbone of the star topology is connected to SONNET (the OSU campus
 network) through the departmental firewall. Our connection speed is currently
 10 MB/s to SONNET. We plan to upgrade it to 100 MB/s some time this fall.
 
 All our buildings, except JL and 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 the hub or switch on your floor and
 allows you to use the entire bandwidth of that connection (10 or 100 MB/s,
 depending on the hub or switch on your floor). The network in JL and EL is
 still 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.
 
 Even at the same nominal speed of 10 MB/s, coax is much much slower than
 twisted-pair because the bandwidth is shared between all computers on a
 segment. JL is scheduled for renovation this year, and the network will be
 upgraded to twisted-pair. 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,
 which resulted in a modest speedup and lower latency. It will take several
 years until the network in EL can be converted to 10/100 MB/s twisted-pair
 cabling (depending on funding). Twisted-pair is faster, much more secure and
 more reliable, and we would like to convert the network as soon as possible.
 
 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.