STUDY GUIDE
Introduction to Routing Fundamentals and Routing Protocols
Objectives
This module covers the following objectives about how a router in a network works, basic configuration,
verification and troubleshooting of Cisco Router in a simulated environment:
➢ Describe the features and behaviors of a router inside a network environment.
➢ Discuss basic routing concepts such as packet forwarding, types of routing protocols and router lookup
processes.
➢ Verify network connectivity using ping, traceroute and SHOW commands for best route determination.
Study Strategies
➢ Read and patiently understand the discussion presented in this module.
➢ Smartly rewrite in your notebook or make a summary of notes about the information being presented. By
this strategy, you will learn how to visualize the concepts and imagine how a switch fundamentally
operates in a network environment.
➢ Complete the challenge and the exercises at the end of the module. This will solidify the concepts that
you have learned through simulation. Simulation will be done by group and you need to collaborate with
your group members.
Introduction
After discussing the basic switching processes, commands, configurations, and related layer 2 protocols,
we will now be discussing the fundamentals of routing. Recall that we can use switch to connect our devices
within our local area network and that’s fine since the scale for our network environment caters enough users to
access our devices. Switch, especially layer 2 switches, can forward traffic within the network using MAC
addressing scheme. We have also learned that switches can offer different methods to secure the traffic dedicated
with each device through virtual segmentations (VLANs) and preventing loops when implementing redundant
links (STP).
But as far as scalability is concerned, and if we wanted to stretch our network to communicate with another
local area network and with the Internet, the process of forwarding the traffic cannot be done anymore by an
ordinary layer 2 switch. Some may use layer 3 switch since it has “layer 3” capability or the capability to route
traffic from one network to another. Despite of this powerful capability of being a switch, layer 3 switch has
limited routing protocols that it may perform. And by industry practice, it is more efficient to use a device that
has a sole function of forwarding packets from one network to another – this is the router.
And for this module, we will be discussing different concepts on routing fundamentals and essential
routing protocols used nowadays. Let’s go!
How do routers work?
The main function of a router, as its device name implies, is to route packets or forward packets. Notice
the term “packets” because recalling on our face-to-face lecture before, we have learned that the routers work in
layer 3 of the OSI or even of the TCP/IP models. The packet data unit (PDU) we are using in this layer is “packets”
so it is vital the we have really understood the concepts of the OSI and the TCP/IP layers.
JCQ.ECE 1
, While switches operate really in layer 2 and use MAC address to forward frames, routers on the other
hand operate in layer 3 and use IP address to forward packets. Suppose we have a simple diagram below showing
PC_A sending a request to PC_B with proper configurations of the default gateways on interfaces Gi0/0 and
Gi0/1.
Hi Router! I want to send a
message destined to this IP
address: 192.168.7.21. Can
you help me?
ACCOUNTING
DEPARTMENT
fa0/0
Gi0/1
Gi0/0
fa0/1
PC_A PC_B
192.168.4.12 192.168.7.21
ADMIN
DEPARTMENT
The request from PC_A will be encapsulated with its source IP address (192.168.4.12) and the destination
IP address (192.168.7.21) and will be sent to the router. Note: I just mentioned only source and destination IP
addresses in the ethernet structure to simplify the explanation.
Hi PC_A! I just received your
request through your default
gateway. Sure that I can help
you, let me check in my
routing table.
ACCOUNTING
DEPARTMENT
fa0/0
Gi0/1
Gi0/0
fa0/1
PC_A PC_B
192.168.4.12 192.168.7.21
ADMIN
DEPARTMENT
Once the router received the request, the router will check its source IP address and destination IP address.
The router will see if it has a route or a way to forward the request to its destination and it will do this process by
JCQ.ECE 2
Introduction to Routing Fundamentals and Routing Protocols
Objectives
This module covers the following objectives about how a router in a network works, basic configuration,
verification and troubleshooting of Cisco Router in a simulated environment:
➢ Describe the features and behaviors of a router inside a network environment.
➢ Discuss basic routing concepts such as packet forwarding, types of routing protocols and router lookup
processes.
➢ Verify network connectivity using ping, traceroute and SHOW commands for best route determination.
Study Strategies
➢ Read and patiently understand the discussion presented in this module.
➢ Smartly rewrite in your notebook or make a summary of notes about the information being presented. By
this strategy, you will learn how to visualize the concepts and imagine how a switch fundamentally
operates in a network environment.
➢ Complete the challenge and the exercises at the end of the module. This will solidify the concepts that
you have learned through simulation. Simulation will be done by group and you need to collaborate with
your group members.
Introduction
After discussing the basic switching processes, commands, configurations, and related layer 2 protocols,
we will now be discussing the fundamentals of routing. Recall that we can use switch to connect our devices
within our local area network and that’s fine since the scale for our network environment caters enough users to
access our devices. Switch, especially layer 2 switches, can forward traffic within the network using MAC
addressing scheme. We have also learned that switches can offer different methods to secure the traffic dedicated
with each device through virtual segmentations (VLANs) and preventing loops when implementing redundant
links (STP).
But as far as scalability is concerned, and if we wanted to stretch our network to communicate with another
local area network and with the Internet, the process of forwarding the traffic cannot be done anymore by an
ordinary layer 2 switch. Some may use layer 3 switch since it has “layer 3” capability or the capability to route
traffic from one network to another. Despite of this powerful capability of being a switch, layer 3 switch has
limited routing protocols that it may perform. And by industry practice, it is more efficient to use a device that
has a sole function of forwarding packets from one network to another – this is the router.
And for this module, we will be discussing different concepts on routing fundamentals and essential
routing protocols used nowadays. Let’s go!
How do routers work?
The main function of a router, as its device name implies, is to route packets or forward packets. Notice
the term “packets” because recalling on our face-to-face lecture before, we have learned that the routers work in
layer 3 of the OSI or even of the TCP/IP models. The packet data unit (PDU) we are using in this layer is “packets”
so it is vital the we have really understood the concepts of the OSI and the TCP/IP layers.
JCQ.ECE 1
, While switches operate really in layer 2 and use MAC address to forward frames, routers on the other
hand operate in layer 3 and use IP address to forward packets. Suppose we have a simple diagram below showing
PC_A sending a request to PC_B with proper configurations of the default gateways on interfaces Gi0/0 and
Gi0/1.
Hi Router! I want to send a
message destined to this IP
address: 192.168.7.21. Can
you help me?
ACCOUNTING
DEPARTMENT
fa0/0
Gi0/1
Gi0/0
fa0/1
PC_A PC_B
192.168.4.12 192.168.7.21
ADMIN
DEPARTMENT
The request from PC_A will be encapsulated with its source IP address (192.168.4.12) and the destination
IP address (192.168.7.21) and will be sent to the router. Note: I just mentioned only source and destination IP
addresses in the ethernet structure to simplify the explanation.
Hi PC_A! I just received your
request through your default
gateway. Sure that I can help
you, let me check in my
routing table.
ACCOUNTING
DEPARTMENT
fa0/0
Gi0/1
Gi0/0
fa0/1
PC_A PC_B
192.168.4.12 192.168.7.21
ADMIN
DEPARTMENT
Once the router received the request, the router will check its source IP address and destination IP address.
The router will see if it has a route or a way to forward the request to its destination and it will do this process by
JCQ.ECE 2
