On our 4 HP workstations the data are distributed on more than 15 disks mounted, for most of them, NFS wide, to provide to every user, whichever machine he may be connected to, an access to his personal information, project data, data reduction software source ...
In order to improve this interconnection between those workstations, we have created a ``pseudo FDDI'' local network which links the machines. The Fiber Distributed Data Interface is based on rings running at 100 Mbits/s.
Since our workstations are located in the same room, we use a concentrator to connect them together. The FDDI network is limited to one single hub backplane on which the concentrator is plugged.
The HP FDDI adapters have only a single-attach station (SAS) feature which limits their use to connecting the workstations with only one pair of optical cables and which does not provide any redundancy. Apart from the concentrator, the DEC hub has also an Ethernet bridge to connect the HP workstations to the IRAM Ethernet network, which includes VMS servers, X terminals and VME micros.
The hub installation was straightforward and used a local terminal connected to the hub to define an IP address.
The firmware was downloaded from a PC and the hub management is based on a solution from DEC, running on a PC which provides a graphic representation of the hub.
The connections between the FDDI ports, the Ethernet bridge and the internal pseudo FDDI ring are achieved through menus and buttons.
This FDDI solution drastically improves the inter-connection bandwidth between
our workstations, as can be seen on the following table:
(nfs asynchronous in write mode means that data are not directly written on disk but only in cache memory on the remote NFS host; data are transferred later on disk).
Although there are a few emerging technologies as fast as FDDI, or even faster,we think that FDDI remains a good choice for high-speed networking without surprise in installation or management.
Alain PERRIGOUARD, Patrick DUMONTROTY