In the last NACS-News, we presented an overview of UCInet (see http://www.nacs.uci.edu/news/97.9.html). Continuing in our UCInet series, we examine some important UCI network performance issues below.
Performance at “the Edges” of the Network
A key network performance consideration is how networks are used within departments and among other groups of people who work together (workgroups). E-mail is exchanged, data and programs are accessed from local servers, printers are shared, and so forth. In the best case, members of a given workgroup are connected to a single Local Area Network (LAN). These workgroup LANs constitute the “edges” of UCInet.
Workgroup LAN performance is often limited by the shared 10 Mbps (Megabits per second) Ethernet speed typical of most campus LANs. Shared Ethernet requires all users to share bandwidth – the more users that are added to the LAN, and the more the network is used, the slower the network becomes. In fact, a single user can unknowingly monopolize shared network bandwidth, and slow response for everyone else.
When workgroups are split over multiple LANs, communication must travel through multiple network “routers” and the network backbone. Latency (response time) in this case is always worse than in single-LAN workgroups. Routers require more time to do their work than LAN switches or hubs, because their task is more complicated, and resource intensive.
Networking in many UCI workgroups currently suffers from LANs with too many computers sharing bandwidth, and from being split across multiple LANs. There is no “quick fix”, as network wiring in many UCI buildings will not support new, higher speed network technologies such as “Fast Ethernet”.
Backbone Considerations
UCInet’s backbone consists of six subnets, five of which use 10 Mbps ethernet, and one of which uses a 100 Mbps Fiber Digital Device Interface (FDDI) ring. The speed of traffic across the backbone depends on which of these subnets is required according to the source and destination of the traffic.
Another issue is the age of routers (up to 8 years old) on the slower UCInet segments. Older routers cannot support current software revisions, in much the same way that older PCs cannot run new system software like Windows NT. Important new features cannot be employed without replacing these routers. The good news is that there is bandwidth available on the FDDI backbone ring to support some additional, new routers and LANs as older routers are replaced.
The Internet and other Considerations
UCI’s off-campus connection can handle more traffic than is currently flowing through it. Unfortunately, the Internet itself has become so slow that some people are expanding the acronym WWW to World Wide Wait! A typical Web request can suffer from a variety of bottlenecks including slow Domain Name Service (DNS) lookup of host names, congestion on networks traversed en-route, a slow destination network, or a slow destination system. Slow response is one motivation for the recent nation-wide interest in a “new” Internet, which will address many of these problems.
UCI’s own network services, such as campus DNS, can also contribute to slow network response if not upgraded to handle expanding demand.
What’s the Plan?
Improving the speed and configuration of campus LANs is a critical UCI network need, as is the upgrade of data wiring and network backbone components. There is much to be done. We will discuss current plans and considerations next time.