DCD Design Note 108.0

FESS Network Restructure

by
David Tang
December 19, 1995

Facilities Engineering Services Sections (FESS) located on 5 East and the Mezzanine of Wilson Hall, has approximately 105 computer systems including IBM PC compatibles, Macintoshes, and UNIX workstations connected to the WH/HIGHRISE1 thickwire ethernet backbone. Systems in WH5E offices connect utilizing thinwire technology to a DEMPR (thinwire repeater), which in turn connects to the FESS router and the WH/HIGHRISE1 ethernet backbone. Structured UTP wiring connects systems in the Mezzanine offices to two Cabletron hubs, which in turn connect to a repeater in WH5E via a fiber pair. The repeater connects to the FESS router located in the same closet. Please refer to Figure 1 for the current network configuration.

As indicated in Jack Schmidt’s December 6, 1996 Acquisition Plan: "A File and Application Server for Facilities Engineering Services Sections," the FESS computing systems in the WH5E and Mezzanine discussed herein are to be connected to the PC Server FDDI LAN.

WH5E and Mezzanine are currently behind an IP/AppleTalk router "r-g-fes". FESS has previously indicated that the AppleTalk routing is very essential to them. It isolates them from the densely populated "MAIN ETHERNET" zone and increases AppleTalk performance on their network.

All physical connections to the PC Server LAN will operate at 10Mbps, but the plan must also be able to accommodate a higher bandwidth of 100Mbps in the future.

Since routing is essential, there are several possible configurations that can accommodate both immediate and future needs. The least complicated method is to connect WH5E and Mezzanine by connecting the existing WH5E router to the existing PC Server LAN etherswitch located in WH7W. The connection will be made over a new multimode fiber pair approximately 700 feet in length. We will install a new 10BaseF transceiver on the "r-g-fes" router, and a 10BaseT to 10BaseF repeater to connect to a port on the PCS etherswitch "s-s-wh7w-pcs1" (Figure 2).

As the network traffic grows, and a higher bandwidth is called for, FESS can form its own workgroup by acquiring a new FDDI concentrator, a 10BaseF etherswitch, and a FDDI interface for the hub router "r-s-hub". The hub router connects to the rest of the site via a port on the Gigaswitch (Figure 3). All FESS sites can easily connect to the etherswitch via a multimode fiber pair, and will receive the benefit of having dedicated 10Mbps bandwidth. If demand grows beyond 10 Mbps at one or more FESS sites, capacity can be increased at those sites by installing local etherswitches. These connect to the FESS workgroup FDDI concentrator by the same fiber pair which had been used to connect these sites to the central etherswitch (Figure 4).

After a meeting with DCD management a final recommendation was proposed. By creating a new FDDI LAN for FESS and extending FDDI to each of site would eliminate all possible traffic bottlenecks both present and future. This is diagramed in figure 5.