Network Design and Implementation: A Comprehensive Report

Desklib provides past papers and solved assignments for students. This report details LAN/WAN design and troubleshooting.

Transport Network Design

Table of Contents
LO1 LAN design principles and their application in the network design process........................................3
LO2 Implement a network using LAN design principles............................................................................5
LO3 Implement a network using LAN design principles..........................................................................10
LO4 Troubleshooting techniques and methods..........................................................................................11
References.................................................................................................................................................13

LO1 LAN design principles and their application in the network design process
Hierarchical design models
The Hierarchical network design model plays a vital role in establishing a scalable and adaptive
network design. It divides the complex networks into multiple sub networks which makes it
better to manage them whenever trouble arises. We can troubleshoot the devices at every
different layer without disturbing the other network components or layers every layer has its own
specific work. By using hierarchical network design models we can optimize our network and
also it become easy for us to select the right components for our network architecture.
An ideal hierarchical network design model contains three layers:
■ Core layer: IT is the uppermost layer where best transport between sites and high-performance
routing occurs. At core layer the high end devices which can maintain the high load and traffics
are deployed as this is layer is critical to threats and traffic directly. So that’s why the design
principles of the core should be very appropriate and it should be able to recover from all the
network failures or any other errors and threats.
■ Distribution layer: The middle layer connects the access and core layer. this is the layer where
we apply various policies for connectivity and also configure the security measures.
■ Access layer: The lowermost layer where the local users are connected. The access layer
provide the network access to the local users .Provides workgroup/user access to the network.
 This hierarchical network also called as 3-tier models.
 2-tier models are also used in some small-scale network enterprises (Eskandarpour et al,
2015)
Network Redundancy
The network redundancy feature allows us to create a backup for our network whenever any
failure arises due to device or link. Redundant links can also provide load balancing into our
networks.
Layer 2 Redundancy
On layer 2 which is datalink layer we use devices like Switch for our network operations. We
can introduce the redundancy at this layer through a protocol called Spanning tree protocol
(STP). STP helps us to create a link redundancy in a LAN environment.

Here we can see that we have a redundancy in our designed model.
Suppose any of the PC from below tries to communicate to PC1 then it has two paths for it.
One is through sw3->sw2 and another one is form sw3->sw1.
The STP protocol here create a BLOCKING port whenever switches are connected like this or in
a loop. The blocking port will become FORWARDING if the primary Forwarding port goes
down.
Issues:
Sometimes a Broadcast storm can be seen into this kind of arrangements. A broadcast storm is a
condition when switches connected in a loop keep sending a same piece of information to other
switches. This increases delay in our network. So our network could become slower than earlier.

LO2 Implement a network using LAN design principles
LAN Devices
We have many network topologies like Mesh, Bus, Star, Tree from which we can decide a
suitable design of our network. Each topology type has its own pros and cons.
Devices
Routers: Router operates at Layer 3 called as Network layer device of OSI mode.The main
objective of this layer is to help us in connecting different networks and subnetworks. We
connect every physical or logical interface of a router to a distinct network. Routers performs
routing to find the best path for a destination. They follow the Routing table which has the best
path details inside it. There are various metrics such as Hop count, Cost, Bandwidth, Delay
which act as a figure for calculating the best path for a destination.
Switches: Switches can operate at layer 2 which is termed as Data link layer of OSI model.
Switch binds its connected devices and nodes into a same network. This same network is also
called as Broadcast domain. Switch use and checks the destination MAC address for taking
packet forwarding decisions. Some of the protocols like ARP (Address resolution protocol),
VLAN (Virtual LAN) works on switch for forwarding the packets from a specified source to
destination.
Servers: We deploy WEB, EMAIL, DNS and FILE servers in our network. Each server has its
own task. We usually place the servers in a separate VLAN or zone. By doing this we can
minimal the attacks which may come in our local area network.
Multi-layer switch: Multilayer switch or Layer 3 switch is Network layer device. It could
perform routing when IP protocols are enabled on it. Still a layer 3 device does not constitute all
features of a layer 3 device (González et al, 2016).
Configuring devices:
1. Connecting Computer, Routers and Switches
Straight and Cross cables: The basic Local area network cables used for wired
connections between network devices like Routers, Switches and computers.
 Straight : Router -Switch, Router -Computers ,Switch-computers
 Cross: Router-router, Switch-Switch etc.
 Serial link cables: To connect to Serial ports.
2. Trunk and Access Ports
 Access ports: Whenever we want to put the interfaces of switch into VLANs we
have to configure them into access mode.

 Trunk Port: A trunk port is responsible for VLAN tagging and untagging. For this
Trunking encapsulation protocol must be enabled on connected ports.
3. IP address (IPv4)
 The “IP address” should be written with subnet mask. Subnet mask helps us in
identifying the value of Network and host bits.
On PC’s
For assigning the IP addresses to the PCs and other hosts in the network , we will use method of
Dynamic IP allocation which is through DHCP (Dynamic host configuration protocol).We will
create a DHCP server. The devices will be configured to DHCP mode and hence they will be
able to receive DHCP IP address.
 Enter into Global configuration mode of router.
 Give a Domain name of your DHCP server.
 Then create an IP address pool.
 Now go to network adapter settings of PC and set the IP allocation method to
DHCP from static.
 To check the connectivity, use the PING command

4. VLANs on switches
Here we are using the concept of Inter-vlan routing.
In intervlan routing we will create subinterfaces on router so that we can make different
subnets on a same router interface. This helps us in rate cutting of the resources in our
network.
Configuring the subinterfaces.

By default all devices which are connected to switch are in same broadcast domain
because all of the ports are assigned into VLAN1.
In order to restrict communication between different PCs we have to put them into
different VLANs . After we assign them into different VLAN they will belong to
different broadcast domains and hence will not be able to communicate to each other.
Before assigning ports into different VLANs we have to change their interface mode to
access mode
5. Local Servers:
 DNS (Domain name server):- DNS servers task is to resolve the IP address to a domain
name or a domain name to its respective IP address. For this we have to create a database
into DNS server which will have all the bindings and conventions of different Hostnames
and their respective IP addresses.
 WEB Server: A Web server is responsible for giving response to every HTTP (Hyper-
text transfer Protocol) or HTTPS(Secure HTTP) requests. Some other capability of
webserver also includes the websites hostings, webpages and other internet related
services.
 FTP Server (File transfer protocol): Uses TCP port not 20 and 21; one for downloading
and one for uploading .Any request related to file sharing , downloading and uploading is
checked or go though by FTP server
 Email Server or SMTP (Simple mail transfer Protocol): SMTP protocol uses protocol
port 23 for transferring Mails from server to client. While SMTP is mail transfer protocol
from server to client, IMAP, POP3 (post office protocol ) are used to download those
mails on client computer (Soleimani et al, 2017).
6. Port-security:

The Port-security plays an important role when it comes to protect our switchports
against unauthorized access. The port security feature lets you configure many security
features like Number of MAC addresses to be allowed on a switchport, violation mode
from RESTRICT ,SHUTDOWN and PROTECT modes and also how a device will register
itself on switch. Through this we can define the legitimate users of the network.
Commands
7. User Authentication:
 Routers and switches allows us to create a local user database.We simply have to
set a username and password for the users who are allowed authenticated to
configure devices of our network.
Commands
Switch (config )# username cisco password cisco

IP addresses table:
Main Branch
Department NETWORK VLAN Gateway
SALES 192.168.1.1/25 1 192.168.1.1
DESIGN 192.168.1.128/26 2 192.168.1.129
FINANCE 192.168.1.192/28 3 192.168.1.193
IT 192.168.1.208/29 4 192.168.1.209
SERVERS 192.168.1.216/29 5 192.168.1.217

LO3 Implement a network using LAN design principles
A Wide area network WAN is deployed when we have two areas which are geographically far
and apart. We can use the common ISP connection to establish a link between two different
LAN. We can either deploy a private or a public WAN.
The public WAN can be established using :
1. PSTN (Public switched telephone networks) or
2. another popular method INTERNET.
 The Internet method is most reliable and less cost solution.It is also easy to
establish VPN connections with the internet. A VPN allows us to establish a
secure, encrypted method to connect between two geographically apart LANs.
 Here we have used a Public IP range of 30.40.50.0/30 which will give us two
valid host IP addresses.
Advantages of Public WAN:
 Available everywhere;
 Less costly;
 Easy to manage and technologies needed for implementation are easily available
Disadvantages of Public WAN:
 Security can be compromised sometimes.
 Abrupt disconnection
 Internet can go down anytime leading to its unreliability.
Private Networks: Private Networks can be the best way to make connection between two LAN
if there is no problem with the budget. Private network can include multiple technologies but the
organization’s requirements are the main consideration while designing a private network.
Introduction of Fiber based networks can bring so many advancements into our network.
Advantages of Private Networks:
 Security is very less compromised.
 Communication between organization is very fast and efficient.
Disadvantages of Private Networks:
- Costly as compared to any of the method used in Public networks
- Requires more administration.
- Separate network administrators should be hired in order to provide maintenance to the WAN.

- Complexity increases with time.
LO4 Troubleshooting techniques and methods
Monitoring of network
 For the network monitoring, we can either see the logs on our devices or can configure a
different SYSLOG server.
 It is advised to keep logging messages as disabled on the console of the devices because
there could be too many logs coming in and out.
 Monitoring is one of the main task when it comes to identify the threats and attacks.
Monitoring person should be well known with the messages types, flags etc.
 There are some other software like CACTI, ZENOSS which servers as monitoring tools.
They can inspect the packets to layer 3.
Troubleshooting of network
Some of the network issues which can arise:
1. Link disturbance: the link connecting the two devices or peripherals can sometimes
become loose causing network delay and network disturbance. Make sure every link is
correctly connected and attached.
2. Physical interfaces: Sometimes protocol changes can cause our physical interface to go
down or up. We must check the status of these interfaces one we are done configuring the
changes.
3. Window network troubleshooting : this is a underrated yet most useful mechanism to
identify the network issue. We can simply run Network troubleshooting software
installed on our PCs to identify the issue. Sometimes it is able to automatically solve the
problem by driver updates or some other updates.
4. PING and TRACEROUTE commands: these two commands are very useful when we
want to check connectivity to our network. PING command simply sends some ICMP
packets from one host to another host. If a successful PING is done then it ensures our
network connectivity. On the other hand TRACROUTE command is used when we want
to check our connectivity hop by hop. A packet may passes through so many hops to
finally reach its destination. So if a packet gets dropped, we can check that upto where
the packet is reaching by using TRACEROUTE command.
5. Problem may also arise from ISP side. It is always recommended to take connection from
two ISPs considering one as Primary and other as Secondary.