New UCInet Backbone

The implementation of UCI’s new network backbone began in January and is proceeding on schedule. The Gigabit Ethernet, fault-tolerant, backbone “core” has been tested and placed into production. The implementation team is in the process of connecting buildings to the new core that had been on an interim Fast Ethernet backbone. The team is also configuring and testing the building switches that comprise the rest of the backbone.

The plan is to move the bulk of campus subnets to the new backbone over the summer. Moving departmental subnets will require a few hours of network downtime in each building. Each outage will be scheduled in advance and announced on the UCInet-OPS@UCI.EDU LISTSERV mailing list. In addition, the full schedule will be maintained on the Web:

The new backbone will address rapidly growing communication needs, provide a foundation for ongoing departmental network improvement projects, and ensure continued, reliable operation of the critical campus data communication infrastructure. For more information, please see:

Questions about the project may be addressed to Garrett Hildebrand, whose e-mail address is GDH@UCI.EDU.

UCInet Performance Considerations

In the last NACS-News, we presented an overview of UCInet (see 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.

UCI Network Overview

With the growing utilization of electronic communication in all aspects of University affairs, the campus network (UCInet) has become a critical campus asset. As communication needs continue to grow and change, the network must be maintained and enhanced to keep up. This requires a substantial campus investment. To facilitate discussions, NACS seeks to broaden campus understanding of network issues and options. Toward that goal, this article summarizes the layout and important components of UCInet. Subsequent articles will address current performance issues and planned improvements to UCInet.

UCInet may be logically grouped into six fundamental components, as follows:

1. Departmental and organizational LANs (Local Area Networks);
2. The campus backbone;
3. Network services;
4. WAN (Wide Area Network) connections;
5. Internet connectivity;
6. Remote access (e.g., modems and related equipment)

Departmental LANs, which connect to the backbone via devices known as routers, may be viewed as the “edges” of the network. UCI has a diverse collection of LANs. Most operate as “shared Ethernet”, meaning that connected computers “take turns” utilizing the network’s 10 Mbps (Megabits Per Second). LANs provide communication between computers within departments, and the routers they connect to provide links to the campus backbone and the services UCInet supports.

The UCInet backbone is the binding tie that connects LANs, the Internet, and other networks, such as the UCI Medical Center. It may be viewed as the “core” of the network. UCInet’s backbone has about fifty routers, each with multiple interfaces, for a total of about 350 LAN interfaces on campus.

“Network services” are computer-based services required by all users of the network. One example is the campus Domain Name System (DNS) servers, which provide translation of network names to network addresses. Applications such as Netscape cannot connect to a Web site until a DNS server answers a query for translation of a domain name to an Internet address.

Network services operate behind the scenes and are transparent to users. When a Web server fails to connect to a Web site, a user cannot distinguish between a network outage and a bad DNS lookup. In fact, one may cause the other!

UCInet has several WAN links to support outlying campus facilities. These links allow network users at sites like the Medical Center to appear as if they are on campus, albeit at slower speeds. “T1” (1.5 Mbps) WAN links are six times slower than the standard 10 Mbps Ethernet now widely in use.

Internet connectivity is provided throughout UCInet from another network called UCnet, which connects all UC campuses together. UCnet currently operates at a speed of 10 Mbps. However, UCI and UC Berkeley connect to UCnet and the Internet at “T3” (45 Mbps) speeds, as they are the UCnet network access points for the Internet.

Remote access to UCInet is accomplished via the campus modem pool and the Internet. Users may dial-in to UCInet through the modem pool or access UCI systems through their own Internet Service Provider.

UCInet is a diverse collection of networking and computing technologies which supports over 14,000 computers, printers, hubs, routers and other network devices, plus several hundred dial-in connections and countless visits from the Internet. In our next NACS-News network article, we will discuss UCInet’s most significant performance issues.


NACS has been reviewing UCI network needs over the past year toward the creation of “UCInet 2001”, a draft UCI network plan covering approximately the next 4 years. This process has included improving our ability to gather and analyze network use statistics, investigating network performance “hot-spots”, interviewing faculty about current and future needs, and staying in touch with the rapid changes currently taking place in network technology and national network infrastructure. NACS is currently in the process of presenting our initial conclusions to campus and external advisory groups for their review and comment. The first of several articles on the topic of UCI network issues and plans follows below.