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  OIT Home > Committees > CNC-BEG > BEG Short-Term Plan
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BEG Short-Term Plan



The purpose of the Short-Term Plan, referred to herinafter as the "Plan," is to recommend an implementation plan to allow for a rapid (i.e., within three months of funding approval) migration from the 5 megabits-per-second (Mbps) broadband-based backbone to a new, fiber-based 100 Mbps backbone with 10 Mbps access.

This Plan will make estimates for funding and recommendations for equipment, installation, operation, and management.


The Plan funding and implementation applies only to buildings and departments which have fiber optic cable already installed; these applicable departments will be referred to as the "Department." Buildings or departments without fiber optic cable already installed must continue to use the Ethernet services over the broadband.

Backbone Technology

This Plan recommends FDDI (Fiber-Distributed Data Interface) for the new, fiber-based backbone technology. The reasons for this recommendation are:
  1. FDDI is widely implemented, and has been for several years, and is readily available from almost all router vendors, using "off the shelf" technology.
  2. FDDI is ultra-reliable, and is designed to provide network services despite loss of one or more entire fiber segments, or components.
  3. FDDI is ultra-reliable, and is designed to provide network services despite loss of one or more entire fiber segments, or components.
  4. FDDI remote management software are is available.

    The only other currently popular, available, high-bandwidth technology is ATM (Asynchronous Transfer Mode). ATM is not currently suitable as a backbone protocol for a campus-wide, production IP network, for several reasons, the most important of which is that ATM, while widely deployed in many "test bed" networks, is still not a completely specified standard; it is still under development. In particular, IP interoperation with ATM is still being worked on.

Backbone Structure

This Plan recommends a "semi-collapsed backbone", consisting of Network FDDI/Ethernet Switches1 and Network FDDI Concentrators2. Concentrators will provide direct access to the new network via FDDI ports, and Switches will provide indirect access to the new network via Ethernet ports.

The reasons for recommending a "semi-collapsed backbone" are:

  1. A single switch as a completely collapsed backbone is not possible, because there is no single point from which all fiber runs to all other buildings or departments are less than the two kilometer limit of multi-mode fiber signalling.
  2. A switch per Department is not economically feasible.

Network FDDI Concentrator

A Concentrator provides a "Dual Access Station" (DAS) FDDI port3 connection to the backbone, and several "Single Access Station" (SAS) FDDI ports4 for attached FDDI interfaces. It is an important feature of FDDI concentrators that they keep the number of DAS port connections to a minimum, since these are potential points of failure, where a "ring wrap" can occur, which affects the entire FDDI ring. The SAS port connections on concentrators are typically isolated from the ring when the attached equipment or fiber fails.

The Concentrators will be required at locations where additional FDDI attachments are expected. For example, it is expected that Communications Services, in the Public Safety Building, will require one since they will (probably) require both a Switch and a management station for remote network management. Similarly, buildings such as North Hall and Engineering, which are already expecting to have direct FDDI attachments, will require Concentrators for their direct access.

Network FDDI/Ethernet Switch

The Network FDDI Switches, which will be connected over the fiber into a logical FDDI ring, must have the following features:
  1. FDDI DAS port interface, unless co-located with a Concentrator.
  2. Two or more Ethernet interfaces, using either Unshielded Twisted-Pair (UTP) or Fiber Optic Inter-Relay Link (FOIRL) Ethernet connectors
  3. "Translation bridging." Generally, this is preferred over routing, as the overhead of routing is unnecessary in this application, and requires greater management effort. However, routing provides better administrative control over the attached Department LANs, which may be a consideration for insecure LANs (such as the planned connections in Residential Housing).
  4. SNMP supported, allowing for remote management by standard IP network management software.

Network Access Connectors (NAC)

For each Department, this Plan will provide access to the new Network in the form of an Ethernet AUI connector (DB-15). The current broadband-based backbone uses Ungermann-Bass Buffered Repeaters (UBBR) with AUI Ethernet ports. This Plan will replace the UBBRs with a new Network Access Connectors, or NACs.

The new NACs will either be FOIRL to AUI transceivers, using fiber cables to interconnect, or UTP to AUI transceivers, using UTP cables to interconnect, depending upon the corresponding port on the connecting Network Switch.

NAC Location

The location of the new NACs will be either the "point of entry" for the fiber optic cable for each Department, or the closest UBBR being replaced by the new connection. In those cases where the UBBR is at a different location within the building than the new NAC, this Plan will supply the fiber and equipment between the nearest Switch and the UBBR.

FDDI Access

This Plan is funding only the Network Concentrators, Switches, and Converters; it will not fund any FDDI interfaces to provide for direct access for a Department, but will provide for such connections, under the following conditions:
  1. The Department FDDI interface must be a Single-Access Station (SAS) port.
  2. If the Department is located in a building not already housing a Network FDDI Concentrator, a set of fiber patches to the nearest Concentrator must be run.
  3. The FDDI interface must be to a LAN router for the Department.
  4. The Department LAN router must support SNMP, and be SNMP manageable.
  5. The password to the Department LAN router must be provided to the Network Operation Center.
  6. The Department LAN router manager must provide contact information for problem escalation procedures.
The effect of points 1 and 2 are to ensure that all physical connections to the FDDI backbone are a Network Switch or Concentrator, allowing the Department router to be bypassed automatically when it fails or goes off-line without requiring a "ring wrap" of the Network backbone.

It should be emphasized that the intent of this Plan is not to induce new FDDI connections, but to provide for a rapid, economical migration from the broadband-based network to a fiber-based network, where possible.

Backbone Topology

Diagram of the Planned Network

Building Fiber Connections

Each building with a fiber optic cable termination has a Building Termination Panel (BTP) and at least one Customer (or Department) Patch Panel (DPP) installed at the building's point of entry.

For Departments in buildings with an installed DPP, the new Network connections for the Department should be a straightforward patching of unused fibers from the BTP to the DPP, and from the DPP to the NAC forming part of the new Network.

For Departments which have not allocated any fibers and thus have no DPP, this Plan will provide a Network DPP between which connections can be jumpered with the BPP. If the location of the UBBR being replaced requires an intra-building fiber optic cable run, an additional Network DPP may be required, from which the fiber cables to the NAC can be jumpered. The situation is depicted in this diagram.

Equipment & Costs

The following table lists the equipment required for the implementation of this Plan, and their estimated costs.

Item Qty Unit Cost Extended Cost
FDDI Concentrators 4a $10,000 $40,000
FDDI Switch (A/B Port, 8 Enet 4b $10,000 $40,000
Additional Fiber-runsc 1 $20,000 $20,000
Uninterruptable Power Supplies (UPS) 5 $750 $3,750
Fiber-optic cable jumper installationd 1 $15,000 $15,000
Ethernet transceivers (FOIRL/AUI) 35 $380 $13,300
Network Monitoring Stations & Software 2 $12,500 $25,000
Contingency 10%   $16,000
TOTAL $173,050
aIncludes one spare.
bIncludes one spare.
cIncludes fiber optic cables and any necessary DPPs.
dEstimated at $75 per jumper and 1 hour per location by Communications Services.


This Plan recommends that an operating budget be developed to cover the annual maintenance costs of the Network equipment, including any license costs for the network management software.

Network Operation Center

In order to provide for consistent, reliable maintenance of the new Network, this Plan recommends that a UCSB campus Network Operations Center (NOC) be formed to operate the Network and provide support for it.
  1. Funding & Equipment
    The NOC must be funded and equipped with the proper tools to manage the Network. At the very least, a network management station, with both FDDI and Ethernet interfaces, and acceptable network management software should be available to the NOC.
  2. Initial Staffing
    Since one of the goals of this Plan is for a rapid deployment, and since the creation of any new organization is anything but rapid, it is further recommended that the initial NOC be comprised of selected departmental network manager staff who are already responsible for operating large departmental LANs, and have the support of their departments for their involvement with this "virtual" support center.

1The word "hub" is sometimes used in this context. A "switch" is distinguished from a hub in that the former can provide intelligent, optimized data flows between neighboring ports, while the latter is typically not much more than a multi-port repeater. However, some vendors do not follow this nomenclature -- hence, the confusion.
2To further confuse matters, with vendors of modular products, the only difference between a "concentrator" and a "switch" or "hub" is that the former is composed of similar ports (eg: all FDDI ports), while the latter are composed of dissimilar ports (one FDDI port and several Ethernet ports).
3Also called an "A/B port."
4Also called an "M port."

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Last modified: 10/19/2007