(2) WAN Physical Topology


Note: Refer to the next section for IP address allocation pictures.

Topology

Note: In the absence of any real physical topology diagram here is what the logical topology looks like:

List of Routers

Location/Site Routers Required Electronic Needs Usage/Purpose
Regional Hubs:
Data Center (core) 2

1 or more (probably 8 if using T1 or 2 if using T3s) pri interfaces (via Frame Relay) connecting to the ISP
& 1 high speed fibre interface to the main "Data Center" router.

This the the "Internet Firewall" router where ACLs prevent the outside world from accessing any of the schools, but allow schools Internet connectivity and access to the services on the public network

19 pri interfaces (8 T1 connections to WAN Core + 11 T1 connections to schools)
& 1 high speed fibre interface to the "Internet Firewall" router (where all the ACLs are).

These 3 routers form the WAN core. They allow schools access to the "Internet Firewall".

{note: since the links form a triangle, if the connection (involving 4 T1s) between any two regional Hubs breaks, traffic between these two Hubs is still possible via two "sides".}

Service Center (core) 1 19 pri interfaces (8 T1s to WAN Core + 11 T1s to schools)
& 1 BRI interface (for the ISDN connection to the Community School)
Shaw Butte School (core) 1 19 pri interfaces (8 T1s to WAN Core + 11 T1s to schools)
Schools:
Data Center 1

Each school will chose its own router & LAN setup, but the mimumum requirements are as follows:

  • 1 pri interface (to connect to the WAN core via T1)
  • at least one ethernet interface - 3 or more are recommended, as is a subnet scheme similar to Acasia
    • using 100BaseT or TX for these interfaces is recommended

 

{note: A school can have more than one router, but only one is recommended - unless it grows substantially, more than one router is overkill}

{note: since a PPP connection to the WAN core is used the router need not be a cisco router.}

{note: Shaw Butte school is a special exception whereby a T1 line is not needed to connect to the nearest regional Hub. Shaw Butte is a regional Hub, therefore a faster, more expensive connection can be used.}

Allows school connectivity with WAN core (at 1.54 Mbps).

Each school's router uses ACLs to form a second firewall to protect against other schools.

The router is also a pivotal device in seperating the administration and student devices within the school.

Desert View 1
Sunnyslope 1
Mountain View 1
Road Runner 1
Washington 1
Lake View 1
John Jacobs 1
Ironwood 1
Desert Foothills 1
Chaparral 1
Cholla 1
Shaw Butte 1
Richard E. Miller 1
Royal Palm 1
Alta Vista 1
Cactus Wren 1
Manzanita 1
Maryland 1
Ocotilla 1
Orangewood 1
Palo Verde 1
Service Center 1
Sunset 1
Acacia (*our school*) 1
Mountain Sky 1
Tumbleweed 1
Sweetwater 1
Sunburst 1
Sahuaro 1
Blue Sky 1
Moon Mountain 1
Lookout Mountain 1
Abraham Lincoln 1
Community School:
Home School Center 1

1 BRI interface (to form its permanant ISDN connection to Shaw Butte),
& 1 or more Ethernet interfaces

Allows the small community school to have a small number of user who can connect to the Internet via ISDN (at 144 Kbps).
       
Total 39 Routers    

Other Devices

  • 4 x servers - E-mail, DNS, DHCP & Web server
    • {note: it is possible to combine all these 4 services into just one server (or 2 servers, or 3 servers), but for the purpose of clarity 4 have been proposed}

  • {note: for each of the routers above, a number of quite expensive router modules will be necessary}

 

List of Media

  • 33 x T1 connections between schools and WAN core
  • 33 x emergency dial-up ISDN lines (via phone lines) from each school to the nearest regional Hub
  • 1 x permanant dial-up ISDN connection via phone lines from the community school to Shaw Butte

  • 12 x T1 connections between the 3 regional Hubs of the WAN core
    • another 12 x T1 redundant links have been proposed.

  • several short lengths of gigabit ethernet (CAT 5) to connect the DataCenter router to the Firewall router, and all of the servers (E-mail, DNS, DHCP & web server) on the public network to the Firewall router.

  • {note: this list of media does not include the media necessary for Shaw Butte school - just the media necessary to form the WAN core and public network}

 

Note: The first thing you would normal do is draw up a physical topology diagram for an overview of how the WAN pieces together and to work out cable lengths etc, but this is not asked for; besideswhich the only physical map we could find is the crude diagram below.

{note: many of the schools we need are missing, but Acasia (our School) and Shaw Butte (our regional Hub) are highlihted}