Dr. Abdul Malik Khan
ASSIGNMENT-2 Specifications and Discussion:
LAN, WLAN & WAN Design
• Network Hardware
• Network Software
• Network Planning & Design
Reference:
“Local Area Network Management, Design and Security: a Practical Approach” by
A. Mikalsen and P. Borgesen, John Wiley and Sons, 2002.
Link: http://library.monash.edu.au/vwebv/holdingsInfo?bibId=1850098
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Network Hardware
• Network services
• DHCP, DNS, Apps Servers
• Internetworking devices:
• Layer-2 Switches
• Layer-2 Wireless Access
Points
• Layer-3 Building Routers
• Network Gateways
• Network Interface Cards
• Connectors
• Transmission Media
Cables:
– Structured Horizontal
Cabling (Floor Cabling)
– Structured Vertical
Cabling (Within
Building)
– Structured WAN
Cabling
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Hubs(obsolete) or Switches?
• Provide an easy way to connect network cables.
• Physically, the network is setup as a star.
• Reasonably easy to install.
• Hubs usually act as repeaters (amplifiers +
retiming).
• Switch offers advantages:
– Each device may be allocated dedicated capacity.
– Useful for supporting a large number of connected stations.
– Allows network management and intelligent path selection.
– Have become more affordable.
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Server
Servers
• Small organizations can use a normal PC as a server.
• Large organizations usually use computers built as
servers -- very powerful and can be specialized.
• A LAN generally has many servers (Services).
• The server runs on some network operating system.
• Type of server(services):
– Print
– File
– Database
– Mail
– Web etc.
– DHCP services
– DNS services
– Print Services
– Authentication Servers
– Email Services
– Security services
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Network Cable Planning
• It used to be common practice to install a network
cable wherever it was convenient.
• Now it is critical to plan for effective installation.
• Most buildings under construction have a separate
LAN cable plan as they do for telephone cables.
• Structured horizontal cabling
• Structured vertical cabling
• Structured Backbone cabling
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Software
LAN Host Operating Systems:
• Peer- to- peer connection
• Server based connection
• Example: Windows Server, Novell Netware,
Unix/Linux/BSD/Solaris etc.
Network Application software – requires network:
• Email, Web, FTP, SAP, SSH etc.
• Client server application, e.g., database with Web
interface
• Groupware, SAN’s, VM’s, etc..
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Network Interconnections
Two similar LANs or LAN segments can be connected
using a:
1. Switch - operates at the data link layer
Two dissimilar LANs or LAN segments can be
connected using a:
1. Router - operates at the network layer
2. Gateway - operates at the network layer
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Reasons for having multiple LANs
• Each part of the organization may need to implement
different LANs.
• An organization is often geographically spread over
several buildings separated by considerable
distance.
• Spreading the load across the network is important.
• Isolating traffic within necessary areas only.
• Reliability planning is important – the failures in one
LAN segment should not impact everyone.
• Security planning is important - parts of the network
should have provisions to be isolated.
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LAN Design and Planning
• The basic process involves four steps that are
performed iteratively:
1. Determining and quantifying current work load.
2. Estimation and quantifying future load for LAN segments and
interconnections.
3. Design & planning new LAN-segment and interconnections;
upgrade existing system.
4. Installation of infrastructure and components.
• New LAN design begins from Step 2, but usually
involves some measurement of other sites to
establish expected needs.
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Step 1- Current Load Analysis
• Done by monitoring an existing system.
• The goal is to determine resource demand by applications and
users, and processing demand for all servers.
• Must review the list of applications that currently use the
network to determine the traffic mix.
• Today, much network traffic is produced by
– Web, email, FTP,… especially SPAM – and Internet services
– Groupware business processes
– Multimedia e.g., video-conferencing
• Must assess the number and type of users
• Determine peak (busy) hours and traffic loads
• Network monitoring tools are useful; many open source and
proprietary choices
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Step 2 - Estimation of future loads
• Users identify the services they want to implement during a
planning cycle.
• Users identify volume ranges for the services they are
requesting.
• Network requirements should be organized into mandatory,
desirable, or wish list requirements.
• Assess the relative amount of traffic generated in each
segment, based on some rough assessment of the relative
magnitude of network needs.
• An aggregate resource demand is calculated.
• The aggregate results have to be extended by:
– Overhead
– Contingency workload reserves
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Step 3 - Design & planning of LAN components
• From the study of the previous steps, categorize
the clients, servers and devices as typical or high
volume.
– Typical users are allocated the base level client computers,
as are servers supporting typical applications.
– High volume users and servers are assigned more powerful
computers.
• In designing LANs, practical channel utilization
limits are considered:
– Fast Ethernet - up to 95% utilization
– Gigabit Ethernet - up to 95% utilization
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Step 3 - Design & planning of LAN components
• There are two interrelated decisions in designing network
circuits and devices:
1. the fundamental technology and protocols
2. the capacity of each circuit
• Designing for circuit capacity means capacity planning,
estimating the size and type of the standard and advanced
network circuits for each type of network.
• Assessment based on current and future loads.
• Although no organization wants to oversize its network and
pay for more capacity than it needs, in most cases, going
back and upgrading a network significantly increases costs,
in equipment and downtime.
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Step 3 - Design & planning of LAN components
• The internetworking decision depends on:
– The location of the LAN segments and processing entities
– Level of distributed processing
– Traffic concentration
• The LAN designer faces these alternatives
– Centralized processing and support of a few LAN sites.
– In most cases, private networks are used.
– Distributed processing and support of fewer LAN sites.
– Local LANs are linked to a site backbone and then to
network backbones.
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Step 3 - Design & planning of LAN components
• Design includes the wiring
concentrators and wiring
connections to NICs (network
interface cards) in server and
client stations.
• First, a logical network design
is prepared, then it is mapped
into a physical network
design.
Image source: http://www.more.net/technical/netserv/diagrams/documenting/
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Step 3 - Design & planning of LAN components
• Network modeling and design tools can perform a number of
functions to help the design process:
– Using data on expected
network traffic, we can run
simulations to see if the
network can cope.
– Simulation results will show
the estimated response
times and throughput.
– The use of design tools can
also help in revising the
existing network design.
Image source: http://www.opnet.com/solutions/network_planning_operations/itguru_net_planner.html
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• The purpose of cost assessment is to assess the
costs of various network alternatives produced
from the previous step.
• Some of the costs to consider are:
1. Circuit costs
2. Internetworking devices
3. Hardware costs
4. Software costs
5. Network management costs
6. Test and maintenance costs
Step 3 - Design & planning of LAN components
For Assignment – ignore costs
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Step 4 - Implementation
The following activities are involved in this case:
1. RFP (Request for Proposal)
> While some network components can be purchased off-the-shelf, most
organizations will use the RFP process.
> Vendor proposals are evaluated, and the winner(s) is selected.
2. Conversion planning
> Current network (if any) should be operational until the new one has
been thoroughly tested and proven.
3. Contingency plan for restoring services in case of failures
> to deal with ways for temporarily reconfiguring the network to allow for
continued operation while conducting repairs
4. Recovery plan
> defines methods to restore either a single component of the network or
the entire network to operational status
> should take into account that system failure may result from device
malfunction, natural disasters, fires, sabotage etc.
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Fast Ethernet Designations
Designation Description
100Base-FX 100 Mbps baseband Ethernet over two multimode optical fibers.
100Base-T 100 Mbps baseband Ethernet over twisted pair cable.
100Base-T2
100 Mbps baseband Ethernet over two pairs of Category 3 or
higher unshielded twisted pair cable.
100Base-T4
100 Mbps baseband Ethernet over four pairs of Category 3 or
higher unshielded twisted pair cable.
100Base-TX
100 Mbps baseband Ethernet over two pairs of shielded twisted
pair or Category 4 twisted pair cable.
100Base-X A generic name for 100 Mbps Ethernet systems.
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Gigabit Ethernet Designations
Designation Description
1000Base-CX
1000 Mbps baseband Ethernet over two pairs of 150 shielded
twisted pair cable.
1000Base-LX
1000 Mbps baseband Ethernet over two multimode or single-mode
optical fibers using longwave laser optics.
1000Base-SX
1000 Mbps baseband Ethernet over two multimode optical fibers
using shortwave laser optics.
1000Base-T
1000 Mbps baseband Ethernet over four pairs of Category 5
unshielded twisted pair cable.
1000Base-X A generic name for 1000 Mbps Ethernet systems.
Designation Description
10Gigabit
Ethernet
Ethernet at 10 billion bits per second over optical fiber. Multimode
fiber supports distances up to 300 meters; single mode fiber
supports distances up to 40 kilometers.
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Assignment WLAN Design
• Structured horizontal
Cabling
– Each floor
> Topology
> Cabling
> Switch location
> Cable distance limitation, data
rates
• Structures Vertical
Cabling
– Switch for each floor
– Backbone Cabling
– Router or Layer-3 switch
Note: Lift & Services wells area is the space used for
Lift service, Wells used for running vertical
network cables between floors.
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Assignment WLAN Design
• Building to Building Link design
– Examine the anticipated traffic profile for all the two new
buildings
– Estimate peak volume of data in the new building.
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Structured Horizontal Cabling
Sample Desktop Floor plan
Note: Lift & Services wells area is the space used for Lift service, Wells used for running vertical
network cables between floors.
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