• Penn: Large, urban, private research university; decision making largely decentralized
  • 22,000 students total, 10,000 undergraduate
  • Undergraduate schools: Arts & Sciences, Engineering, Nursing, Wharton
  • Grad/Prof: Annenberg School for Communication, Dental, Education, Fine Arts, Law, Medicine, Social Work, Veterinary Medicine (Vet School has second campus 35 miles west)
  • Major teaching hospital with 7,500 beds
  • Annual budget of $1.9 billion
• Network becoming infused into all aspects of university life: near-universal e-mail, research computing, telecommuting
• Possibility of data/voice/video integration looming
• Still repaying debt on obsolete elements of current network

Network Architecture Task Force

• Charged by Network Policy Committee
• Joint planning with telephony group (organizationally separate from data/video networking)
• Major constituencies represented
• Inter-relationships with other Task Forces and efforts
• Regular meetings since April, 1994 and continuing
• Small sub-committee developed alternatives

Methodology

Definition:
Technical architecture is a blueprint for making technology choices, more a process than a product

Network Needs

Definitions:

• Accessibility: Ability to access network resources whenever and wherever desired.
• Reliability: Consistency and quality with which the network performs.
• Capacity: Ensure that sufficient bandwidth exists to accomplish necessary tasks.
• Capability: Ability to support necessary services given sufficient capacity.

Full discussion...

Assumptions

Definition: Assumptions help bound the set of possible architectures

Examples:

Full discussion...

Network Architecture Template

Three Basic Architectures

Common elements include the following:

Internet connections: Eliminating our reliance on SMDS for connection to the Internet, FDDI is used to allow a scaled connection up to T-3 speed via PrepNet or another access provider.

Inter-campus connections: SMDS appears more appropriate for scalable connections to remote sites within our metropolitan (e.g., New Bolton Center, CJS), replacing dedicated T-1 service. HUPnet is connected via a routed connection scaling from 10 Mb/sec as necessary.

Remote access: The analog modem pool continues to scale to meet demand, shifting to a combination of analog 28.8 bps, and digital ISDN lines (capable of supporting multiple protocols). Commercial access providers may supplement these pools especially for outlying areas.

Advanced networks: Penn will provide coordinating support for advanced networking initiatives that may run counter to our conventional deployments. This will likely include swifter adoption of ATM and direct Internet or vBNS connections for certain projects.

Treatment of legacy network environments: The ISN is eliminated early in 1996; asynchronous terminal server connections are completely replaced by Ethernet early in 1997. No new investments are made in 10-base-2 wire or electronics, and users are transitioned as buildings are renovated and rewired.

Miscellaneous elements:

• Network infrastructure servers are consolidated onto fewer platforms with better redundancy
• AppleTalk and IPX are routed campus-wide and access is provided for remote users
• Desktop hardware and software standards continue to evolve, as Windows 95 use surges
• PennNames, a system for creating a campus-wide unique username space, transitions to feed a DCE secure core, and client/server services (including network access) transition to Kerberos.

Alternative A is the closest to PennNet's current condition. It preserves our current investment in the technology and operations of a central routing core, installs ethernet switches in all buildings, continues EIA/TIA 568 as the wiring standard, but only increases speeds within and between buildings to greater than 10 Mb/sec on a case by case basis.

Major features include:

Inter-building backbone: Collapsed backbone interconnected via FDDI remains, though with fewer, more powerful routers.

Intra-building backbone: Buildings are connected to the backbone via ethernet, or 100+ Mb/sec technology (FDDI or fast ethernet) where necessary for increased bandwidth. Ethernet or fast ethernet switches deployed in all buildings reduce the size of the collision domain within buildings and provide a scalable building interconnection.

Wiring strategies and standards: EIA/TIA 568 continues to be the wiring standard. Ethernet switches are deployed within closets if necessary, though shared ethernets within buildings dominate. Secure hubs prevent promiscuous listening on shared segments. Some 100-Base-X fast ethernet outlets are deployed. Campus ethernet connections begin to migrate towards "personal ethernet" which allows local hubs on 10-base-T or fast ethernet outlets.

Alternative B presents a transition point between Alternative A and Alternative C. The only changes are in the central routing core ("Inter-building backbone"). Rather than a collapsed backbone of routers, the central hub now uses an ATM switch coupled to a "super router" to route between the subnets. A series of smaller routing switches, still located in a central core, start to share a distributed routing load. While management and operations continue to benefit from a single, consolidated location for this equipment, Penn moves one step closer to being able to distribute its routing load to multiple locations when necessary. The nature of the routers and switches at the center are now changing substantially, both in terms of cost and the relative functionality of each object (switching versus routing).

Since ATM switching is now a feature, some direct ATM connections are made possible into the production network either to support advanced projects now in production or servers that require the added bandwidth.

Alternative C: Pervasive ATM

Alternative C represents where the Task Force believes Penn should be in 3-5 years. This is mostly dependent on the necessary investment level, but even more important on the development of products and standards in the marketplace to make deployment of or migration to this alternative possible.

Major features include:

Inter-building backbone: Redundant central hubs, with automatic failover protection, use ATM switching between buildings coupled with a "super router" to route between subnets. An ATM "mesh" is established with some buildings serving as regional "hubs" redundantly interconnected.

Intra-building backbone: Ethernet switches, eventually with ATM and/or distributed routing support ("edge routing devices"), are deployed everywhere to reduce the size of the collision domain within buildings and provide a scalable building interconnection.

Wiring strategies and standards: EIA/TIA 568 continues to be the wiring standard. Ethernet switches are deployed within buildings as bandwidth requirements demand. Secure hubs prevent promiscuous listening on the few shared ethernet segments that remain. Some 100-Base-X fast ethernet outlets are deployed. Campus ethernet connections begin to migrate towards "personal ethernet" which allows local hubs on 10-base-T or fast ethernet outlets. Limited deployment of ATM to the desktop

Three Additional Variations

Alternative A': Pervasive 100+ Mb Backbone

In most respects this alternative is identical to Alternative A, except that in this case there is the need for all buildings to be connected to the campus backbone using a 100+ Mb/sec technology. To accommodate this bandwidth to every building, the campus backbone needs to change: the collapsed backbone is now interconnected via ATM switch to increase capacity at the core. Subnets are connected to central routers via shared or dedicated connections using 100+ Mb/sec technology.

Alternative AB': Distributed Routing with 100+ Mb Backbone

If the availability of the products needed to implement Alternative C becomes more distant, this alternative may provide some necessary solutions. It provides for a regionalized campus with several clusters of buildings connected together via 100+ Mb/sec technology, and fully distributed routing to each building.

Major features include:

Inter-building backbone: FDDI switch deployed to handle multiple FDDI rings (or other 100+ Mb/sec technology) required in this architecture. Central routing is only for outside or inter-campus connections.

Intra-building backbone: Clusters of buildings are connected to the backbone via 100+ Mb/sec technology (FDDI or fast ethernet) for increased bandwidth. Ethernet or fast ethernet switches deployed in all buildings reduce the size of the collision domain and provide a scalable building interconnection.

This alternative allows the campus to migrate more slowly to ATM for inter-building connections.

Major features include:

Inter-building backbone: Central hub starts to migrate to ATM switch coupled with a "super router" to route between subnets. Routing switches at the core start to distribute routing load. Some routers stay on old FDDI backbone providing connections for some buildings. Some direct ATM connections to core permitted as routing switches begin to migrate to buildings.

Intra-building backbone: Buildings are connected to the backbone via 10 Mb/sec or 100+ Mb/sec technology (FDDI or fast ethernet) for increased bandwidth. Some buildings are connected to the backbone directly via ATM and have edge routers installed. Ethernet or fast ethernet switches deployed in all buildings reduce the size of the collision domain and provide a scalable building interconnection.

• This presentation available via WWW. URL: http://nextb.dccs.upenn.edu/noam/questnet96/arch/
• Feel free to contact me later:
  

  	Dr. Noam H. Arzt
  	University of Pennsylvania
  	Information Systems and Computing
  	Suite 221A
  	3401 Walnut Street
  	Philadelphia, PA 19104-6228
  	215/898-3029 (Voice)
  	215/898-9348 (FAX)
  	URL: http://nextb.dccs.upenn.edu/noam.html
  	arzt@isc.upenn.edu (MIME is OK)