1. Overview: District WAN and LAN

• Implement a LAN for local school
• Requirements:
  • (US) $200,000 budget for each school
  • > 7-10 years functionality
  • > 100 times growth
  • > 1 Mbps to every host computer
  • > 100 Mbps to every host server
  • must satisfy TIA/EIA-568-A standards

2. School District WAN Specs

• District schools connect to each other & to Internet via WAN
• Requirements:
  • 3 (interconnected) regional Hubs form the core:
    • District Office Center (single point for all Internet connectivity)
    • Service Center
    • Shaw Butte Elementary School (also includes a community school)
  • each connects to 11 schools
  • Protocols: TCP/IP & Novell IPX

3. School District LAN Specs

There will be 2-segments in each school & also the District Office

• Transport Speeds:
  • 10Base-T
  • 100Base-T
  • 100Base-FX
• Media:
  • Horizontal cable = 100Mbps CAT5 UTP
  • Backbone cable = multimode fibre-optic
• LAN Infrastructure:
  • based on Ethernet LAN switching
• MDF:
  • central point for LAN cabling attachment
• POP for WAN connection
  • Houses major electrical components
• IDF's:
  • used where horizontal cable > 100m or where site conditions dictate
  • connect to MDF in star or extended star topology
• Each Room:
  • has own POP with lockable cabinet for: electrical components & cable terminations
  • supplied with 4 CAT 5 UTP runs (via decorative wire molding)
    • 1 terminates at teacher's (admin) workstation
    • each is tested for 100Mbps capacity
  • supports 24 workstations

4. Servers

• All file servers are categorized as: enterprise or workgroup
  • enterprise - attaches to MDF
  • workgroup - may attach to IDF

Each school will have its own:

• Domain Name Servers (DNSs) & Email Delivery Server:
  • maintain complete directory of all staff & students
  • e-mail server - acts as local post office box & stores all e-mail messages
  • (enterprise)
• Administrative Servers:
  • houses student tracking, attendance, grading & other admin functions
  • available to administration only
  • (workgroup)
• Library Server(s):
  • automated library information & retrieval system - available to entire school
  • will house online library
  • (enterprise)
• Application Servers:
  • houses common user applications (including MS office applications)
  • provides for efficient upgrading of applications
  • (enterprise)
• Other Servers:
  • will all be considered departmental
  • placed according to needs
  • (workgroup)

5. Addressing and Network Management

• At the District Office, a master network management host will:
  • administer complete TCP/IP addressing & naming convention
  • have management rights over all devices
  • store all router configurations
• admin computers will have static addressing
• curriculum computers will use DHCP
• each regional location will:
  • house a regional network management host to support its area
  • use SNMP standards

6. Security

Each school has:

• 3 logical classifications (with secure interconnections):
  • Admin
  • Curriculum
  • External
• 2 physically separate LANs (admin & curriculum)
  • ACL's (on routers) will prevent curriculum accessing admin
  • Admin will be able to access curriculum *
  • e-mail & DNS will pass feely between all LANs
  • each LAN segment will have a file server
• strict user ID & password policy

7. Internet interconnectivity

• Internet interconnectivity (from all computers) will be:
  • supplied though District Office (a single point of contact)
  • available from all schools
  • via double firewall implementation
    • ACL's will prevent connectivity from the outside Internet

   

• A public backbone will be used for Internet exposed services including:
  • e-mail & DNS - which will pass freely in both directions (they pose no risk)
  • a Web server - will allow all schools to upload a home page
  • any other additional web servers

8. User Counts

• For each school assume:
  • max 250 curriculum computers
  • max 75 admin computers
  • each location must accommodate up to 25 computers and include:
    • 1 run for a single teacher/admin computer
    • 3 runs for student/curriculum computer

9. WAN - Media Capacity (not specified in origional)

• Each school is connected (using PPP) via a single T1 (1.54 Mbps) cable to the core network.
• The 3 regional Hubs will be interconnected with 4 T1s between each.
• Any additional links within the regional Hubs should be gigabit connections
• The connection from the Data Center to the Internet (using Frame Relay) has not been specified.
  • This is beyond the course, but this outwards Internet connectivity should be provided by at least 6 (perhaps 8) T1 lines

10. WAN - Expected Traffic Throughput (not specified in origional)

• Throughput is only as good as the weakest link.
• The best throughput for Internet connectivity an individual school could hope for is 1.54 Mbps, however a realistic estimate would involve analysing traffic patterns.
• Ideally, baseline measurements, traffic patterns and throughput are measurements you want to test and monitor rather than guess.
  
  
• The best idea would be look at existing schools (similar to the ones in our WAN) which have Internet connectivity or belong to a larger WAN.
• Only so many student computers would use the Internet at any one time during the school day (say, an average of 10% at a time & a maximum of 40% at once during school hours) - and all would be contending for 1.54 Mbps connection speed.
  • (Imaginary) worst case senario:
    • Lets say Acasia has 250 student and 75 admin computers
    • 40% of student computers (100 computers) and 60% of admin computers (45) are connected to the Internet
    • 1.54 Mbps shared between 145 computers equals 10.6 Kbps per computer.
    • and in reality the actual thoughput for each individual would much less than this (due to contention, collisions etc.)
  • For comparions, your average dial-up rate connect (about 46 Kbps in Australia and probably similar in America) is over four times this fast.
    • At peak times, students will be quite disappointed in their connection speed.
    • If the budget was permitting it might be worth replacing the T1 with T3 (or else installing a second T1)
      
      
• 11 schools connect to each of the regional Hubs, and since these regional Hubs are interconnected by 4 T1s, if all 11 schools are "maxed out" with students surfing web pages/checking e-mail at the same time of the day, the limiting factor (the slowest link) might be these 4 T1s!
  • (Imaginary) worst case senario:
    • (4 * 1.54 Mbps) / (11 schools * 145 individuals online) = 3.9 Kbps per computer
  • Fortunately it's unlikely all schools will be "maxed out" at the same time.
    
    
• Go to the bottom of section "(3) Logical Topology" (in the menu bar) to better understand how internet connectivity will work and where contention will occur.