As the following graphs show, in Figures 1 and 2, the demand for network bandwidth grows inexorably. However, there has been no need for increases in the Janet access speed during this period, and the Janet connection has coped well with the demands on it.
The number of nodes connected via the subnetworks continues to rise, as shown in Figure 3. The basic configuration of the backbone network, a double star network consisting of two central switches and 10 edge switches, connecting to about 190 departmental and college subnetworks, remains unchanged. Figure 4 shows the geographical areas of Oxford covered by the network, and Figure 5 is a schematic of the connections within Oxford and to the Janet network. New applications, in particular those related to the Grid, are expected to bring even greater demands. As the present network is coping well with demand, the planned upgrade of the backbone to 10Gb/second has been deferred until the summer of 2004. The equipment needed has only recently come onto the market, and without an urgent need in Oxford it is better to let this become more established before it is deployed. The gigabit Ethernet backbone, installed in 2000-1, has proved extremely reliable in operation, and has accommodated the growth in demand, as illustrated in Figure 6.
The vital importance of the network, not only to the teaching and research of the University, but increasingly to its business model, is well understood, and is being quantified as part of the current Risk Assessment exercise. OUCS has always striven to build resilience into its network provision and network services. For the backbone network, the “double-star”, with each edge-node connected to both of the central nodes (situated at OUCS and the Museum Lodge telecommunications building) provides resilience against failure of either central node, although the failure of an edge-node will result in loss of connection to units connected to that node. Major fibre connections (eg the link to the Headington hospital departments) are duplicated, but individual cable damage in central Oxford would again result in loss of connectivity to some units. Standby arrangements with cable contractors are in place to ensure speedy repair. Within units, responsibility for provision of IT and communications facilities is devolved.
Although all central equipment is protected from short power interruptions by a UPS, the network connections, and indeed all functions of the University, are vulnerable to external events such as power failure, or civil incidents.
It is becoming increasingly necessary for the University to assess the level of service that it considers essential for it to function, and consider the funding implications of ensuring that level of service. This is not only, or even predominantly, an issue for OUCS: the issues of delivery of administration, teaching and research functions to University members encompass all the central support bodies, as well as those in departments and colleges.
Although the dial-up service continues to be popular and heavily used, the fall in usage noted last year has continued this year as shown in Figure 7 . This is probably because of the increased availability of broadband connection to the home, and the use of VPN through outside ISPs. The service will be kept under review, and line capacity reduced if appropriate.