Washington School District

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Washington School District

• Wide Area Network Implementation
• Jon Carlin
• Shane McDonald

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Wan Implementation Overview

• The WAN will connect all of the schools to the
  three regional hubs and interconnect the regional
  hubs in a full mesh topology. It will also
  connect the Data Center regional hub to the
  internet through a proxy server.
• Connecting the regional hubs and the schools will
  be T1 lines (previously installed). The lines
  interconnecting the regional hubs will also be
  T1s (previously installed). The line running from
  the Data Center to the Primary ISP will be an E1
  (previously installed).
• There will also be an ISDN connection at the Shaw
  Butte regional hub for dial in access. All of the
  connection points for the WAN lines will have
  Cisco Modular Routers. Special WICs (WAN
  Interface Cards) will be used in these routers to
  avoid purchasing of additional equipment

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Physical Topology

• The lines between the regional hubs and the
  schools will be T1 lines running PPP (Point to
  point Protocol). The lines interconnecting the
  regional hubs will also be T1s running PPP.
• The line running from the Data Center to the ISP
  will be an E1 (Ethernet) using Frame Relay. Cisco
  3640 4-Slot Modular Routers will be used in each
  school to connect to the T1 lines. Cisco 3660
  6-Slot Modular Router s will be used in each
  regional hub to connect the individual schools
  and interconnect the regional hubs.
• The WICs being used in these modular routers will
  be of a few different types. The majority of the
  network module cards will be a T1 controller
  cards, available in 2 or 4 ports per card. These
  will be used to connect the T1 lines for the
  individual schools as well as the main T1 lines
  interconnecting the regional hubs.
• The module card in the Data Center will be a WIC
  with one E1 connection port with the DCE (Data
  Communications Equipment) already built in so
  there is no extra equipment to be purchased.
• In the Shaw Butte regional hub there will be a
  specialized WIC that has all of the ISDN
  equipment built in so there will be no extra
  equipment purchase or adapter costs there also.

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Frame Relay

• Frame-Relay is a high performance, efficient data
  technology used in networks throughout the world.
  
• It is a way of sending information over a WAN.
  Frame-Relay is a packet-switched connection
  allowing network devices to share single
  point-to-point links.
• Packet-switched networks enable end stations to
  dynamically share the network medium and the
  available medium.
• Variable-length packets are used for more
  efficient and flexible transfers. Frame-Relay
  does not allow for error checking, however, it
  relies on upper layer protocols, such as TCP, for
  packet checking.
• Most of today's popular LANs, such as Ethernet
  and Token Ring are packet-switched networks.

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• Frame-Relay is a very cost effective
  point-to-point link. It is connected via a router
  by Permanent Virtual Circuits (PVCs).
• There can be only one physical connection to the
  carrier.
• Frame-Relay is consistently less expensive than
  equivalent leased services and provides the
  bandwidth needed for other services like LAN
  routing, voice and fax.
• The T1 connection will occur at the Service
  Center/Data Center/Shaw Butte School Routers to
  the Frame-Relay Cloud.

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Pros (Advantages) of Frame Relay

• Consistently less expensive than equivalent
  leased services
• Provides high bandwidth needed for other services
  like LAN routing

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IGRP - PPP

• Point-to-Point Protocol (PPP) is definitely the
  most widely used WAN protocol in networks
  throughout the United States today.
• PPP provides router-to-router and host-to-network
  connections over both synchronous and
  asynchronous circuits.
• Some flexible features involved with PPP are
  error detection, control of data link setup,
  dynamic assignment of IP addressing, link
  configuration and link quality testing.
• Another flexible value of PPP is that the user
  has the option of using more than one protocol in
  the network design.

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• PPP will use Challenge Handshake Authentication
  Protocol (CHAP) to periodically verify the
  identity of the remote node, using a three-way
  handshake.
• CHAP offers features such as periodic
  verification to improve security making it more
  effective than the Password Authentication
  Protocol (PAP).
• PAP verifies only once and it allows the caller
  to attempt authentication without a challenge
  making it vulnerable to brute-force attacks. This
  is why we chose not to use this.
• CHAP provides protection against playback attacks
  through the use of a variable challenge value
  that is unique and unpredictable. The local
  router is in control of the frequency and timing
  of the challenges.
• PPP, using CHAP, will be implemented throughout
  the Service Center/Data Center/Shaw Butte School
  router connections.

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INTEGRATED SERVICES DIGITAL NETWORK (ISDN)

• The community school is a remote location within
  the Washington Elementary School District.
• This site is small, has a limited number of users
  and will only require connectivity from time to
  time.
• The decision has been made to connect the
  Community School into the WAN core network using
  ISDN technology.
• The Community School will be connected to the
  Service Center WAN Hub, through a BRI (Basic Rate
  Interface) ISDN connection. The BRI connection
  will provide 64 kbps of bandwidth on each B
  channel and 16 kbps of bandwidth on the D channel.

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Benefits of using ISDN on the remote network

• ISDN carries different types of traffic such as
  voice, video and data.
• ISDN is faster than a modem when transferring
  data and telephone lines when setting up calls.
• ISDN is faster that a telephone line when
  setting up calls.

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Problems with using ISDN on the remote network

• Availability - While you can get ISDN, your
  central office may not yet have the software
  needed to implement a full 64 Kbps on each B
  channel.
• Complexity - Not many people are properly
  trained to work on ISDN.
• Cost - ISDN equipment has traditionally been
  high priced.

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IP Adressing for District

• The school district will employ an IP addressing
  scheme using the address of 10.0.0.0. 
• There will be 254 usable subnets and each subnet
  will be capable of supporting 65,534 hosts.  This
  allows for extensive growth without having to
  change the IP addressing of the schools.  
• The administration networks will be assigned
  addresses from 10.1.0.0 to 10.95.0.0 and the
  curriculum networks will be assigned addresses
  from 10.96.0.0 to 10.191.0.0. The WAN's networks
  will be assigned addresses from 10.192.0.0 -
  10.254.0.0.
• The actual assignments of the IP addresses can be
  found in the implementation documentation.

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Redundancy

• Sometimes unplanned system failures happen.
  Failure of important equipment can bring down an
  entire network for extended periods of time. If
  such a failure were to occur in a vast company,
  it could cost thousands or millions of dollars.
• In attempt to make these failures least costly to
  a company, redundancy and backup plans are
  applied. We have implemented redundancy plans in
  the planning of the school district's WAN.

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• If one of the T1 lines interconnecting the three
  regional hubs were to go down, the full mesh
  topology will maintain connectivity while the
  other line is being repaired.
• Using the same modular routers at every school
  allows for a tremendous amount of flexibility.
  Because of the flexibility and cost efficiency,
  spare routers and Network Modules will be kept on
  hand if one were to fail.

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• Backup for the internet service will be available
  as well. If the ISP or the E1 line were to fail,
  a backup proxy server maintaining the same host
  name and ip address will be powered on to
  temporarily provide internet access for the WAN
  until the primary source is repaired.
• This proxy server will be using a separate cost
  efficient ISP that is DSL based.

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WAN Pros and Cons

• Pros
• Flexible modular routers allow for ease of growth
  
• Modular routers make backup plans and network
  changes easy and efficient.
• Backup plans allow for very little network down
  time if any.
• Overall ease of management (excluding ISDN)

• Cons
• Expensive and complicated equipment
• ISDN is difficult to manage and requires trained
  technicians .

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Wan Costs
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The End