Whenever a system connected to the UCInet is discovered attacking other computers, or engaging in other forms of inappropriate behavior (such as the illegal distribution of copyrighted material), NACS may block that system from further network access. Occasionally, NACS may also block systems that have not been patched in a timely manner against particularly nasty viruses.

There are two simple strategies you can follow if you suspect your system has been blocked. You can search the blocked systems list athttp://www.nacs.uci.edu/ucinet/blocked/ (usually, you’ll need to use an unblocked system to do that). Or, you can call NACS at (949) 824-2222. Our helpful consultants will explain why your system was blocked, and what to do to correct the problem. Generally, once you have taken the appropriate steps, the system can be unblocked within a few hours. Please note, however, that unblocking can only be performed during regular business hours except in emergency situations.

NACS is responsible for UCInet, but you are responsible for the proper operation of your own systems. By staying up to date on security patches, and by carefully abiding by the Computer and Network Use Policy at http://www.policies.uci.edu/adm/pols/714-18.html you can preserve your access to the UCInet and help guarantee a secure and reliable service for the entire campus.

Instruction and research on campus and affiliated locations depends on a high-performance network infrastructure, and the University must act to preserve it for its intended use. Beyond this concern, increased downloads from the commercial Internet increases the cost of UCI’s connection to the Internet.

In response, Residential Networking Services has installed a specialized gateway that allows Housing to fine-tune the flow of specific kinds of network traffic. In particular, Housing has limited the amount of total bandwidth that P2P can consume, while keeping connections for academic uses wide open.

P2P applications are not permitted on the campus wireless network (UCInet Mobile Access, http://www.nacs.uci.edu/ucinet/mobile/) because such traffic would overwhelm the network and prevent other uses. Wireless is both a slower technology as well as a shared one (that is, all users are sharing the bandwidth of a single connection). We welcome campus comment on this issue.

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:

http://www.nacs.uci.edu/communication/backbone-schedule.html

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:

http://www.nacs.uci.edu/communication/plans/backbone-plan-1998.html

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

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.

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.