TCP/IP

The sections below will cover the following:

Discuss two common network models (OSI & TCP/IP)
Define a MAC address and IP address
Illustrate how to view these address types from different workstations
Discuss the TCP/IP protocol suite
Q & A to test your knowledge about what you learned

Communications between the two end devices can be broken into layers according to Standardized models, such as Transmission Control Protocol/Internet Protocol (TCP/IP) and Open Systems Interconnect (OSI). These models serve as a guideline for communications and are one of the most important concepts to embrace when designing, troubleshooting, and describing network communications. They are used to:

  • Guide interoperability between products made by different vendors
  • Group communications, hardware, and software into logical layers

The Department of Defense (DoD) and Internet Engineering Task Force (IETF) developed the TCP/IP reference model as a simplified version of the OSI model collapsing the upper 3 layers into 1 layer, and the bottom two layers into 1 (Network access). The most common usage of each is:

  • OSI ~ Used for troubleshooting and interoperability
  • TCP/IP ~ Used to define scope
Network Models

In this section, we will discuss the attributes of the following protocols:

  • Media Access Control (MAC)
  • Internet Protocol (IP)

MAC


A MAC address is a hexadecimal address that is burned into a Network Interface Card (NIC) and is the most commonly used identifier for Ethernet (RFC 5342).

MAC Address

The attributes of a MAC-48 address are:

  • 48-bits
  • Hexadecimal
  • Physical address
  • Layer 2 address
  • Contains two portions: OUI & UI

IP


IP addresses (Ex. 192.168.1.1) are logical identifiers that are assigned to a port.

NIC Port

The attributes of an IPv4 address are:

  • 32-bits
  • Dotted decimal
  • Logical address
  • Layer 3 address
  • Contains two portions: Network & Host

This section will demonstrate viewing MAC & IP addresses from the following workstations:

  • Windows
  • MAC OSX
  • Linux

Windows


The ipconfig command can be used to view the IP and MAC addresses (Technet, 2018).

1
Open a CLI and execute the following command to view the IP address
C:\Users\pkaza>ipconfig
ipconfig
2
Add the /all switch to view the MAC address
C:\Users\pkaza>ipconfig /all
ipconfig /all

Mac OS X


The ifconfig command can be used to view IP and MAC addresses (Mac OS X Manpages, 2008).

1
Open a Terminal and execute the following command to view the IP and MAC addresses
Macs-MacBook-Air-2:~ MAC2$ ifconfig
ifconfig MAC

Ubuntu


The ifconfig command can be used to view IP and MAC addresses (Unix Manpages, 2007).

1
Open a Terminal and execute the following command to view the IP and MAC addresses
ubuntu@ubuntu:~$ ifconfig
ifconfig Ubuntu

IP is a part of software installation known as TCP/IP. Not to be confused with the TCP/IP network model, TCP/IP networking technology is currently recognized as the standard for computer networking. The protocols available in this installation are a part of a protocol suite. Some other protocols included in this installation are (Technet, 2006):

  • ARP
  • TCP
  • UDP
  • ICMP

Below we will view and test this software installation from each of the aforementioned workstations.

Windows


1
Right-click the Network icon located on the taskbar and select Open Network & Internet settings. Then select Network and Sharing Center followed by Change adapter settings and right-click your wireless adapter. Lastly, select Properties
NIC Properties

A loopback can be used to test software installations, running services, and whether or not something is filtered locally. Most workstations contain loopbacks and may be tested using a range of addresses (127.0.0.0/8), where 127.0.0.1 is most commonly setup and used by default.

2
Execute the following command to test that the TCP/IP protocol suite is installed and functioning properly
C:\Users\pkaza>ping 127.0.0.1
Test TCP/IP Windows

Mac OS X


1
Go to System Preferences followed by Network. Then select the wireless adapter and click Advanced followed by selecting the TCP/IP tab
TCP/IP Software

Ping is a command that can be used to test reachability. When pinging the loopback we are testing that we can successfully form what is known as a protocol stack. A protocol stack is hierarchy of protocols used to relay data. When data is encapsulated within these protocols it is capable of being transmitted and is referred to as a datagram.

2
Execute the following command to test that the TCP/IP protocol suite is installed and functioning properly
Macs-MacBook-Air-2:~ MAC2$ ping -c 4 127.0.0.1
Test TCP/IP MAC

Linux


1
Click the NetworkManager icon and select Edit connections.... Then select the connection name and click Edit followed by selecting the IPv4 Settings tab
Network Manager Settings
2
Execute the following command to test that the TCP/IP protocol suite is installed and functioning properly
ubuntu@ubuntu:~$ ping -c 4 127.0.0.1
Test TCP/IP Ubuntu

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