Small Network Applications and Protocols

CCNA Course

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Identify the protocols and applications used in a small network.

After you have set it up, your network still needs certain types of applications and protocols in order to work. The network is only as useful as the applications that are on it.
There are two forms of software programs or processes that provide access to the network:
- Network Applications: Applications that implement application layer protocols and are able to communicate directly with the lower layers of the protocol stack.
- Application Layer Services: For applications that are not network-aware, the programs that interface with the network and prepare the data for transfer.

Network protocols support the applications and services used by employees in a small network.
- Network administrators commonly require access to network devices and servers. The two most common remote access solutions are Telnet and Secure Shell (SSH).
- Hypertext Transfer Protocol (HTTP) and Hypertext Transfer Protocol Secure (HTTPs) are used between web clients and web servers.
- Simple Mail Transfer Protocol (SMTP) is used to send email, Post Office Protocol (POP3) or Internet Mail Access Protocol (IMAP) are used by clients to retrieve email.
- File Transfer Protocol (FTP) and Security File Transfer Protocol (SFTP) are used to download and upload files between a client and an FTP server.
- Dynamic Host Configuration Protocol (DHCP) is used by clients to acquire an IP configuration from a DHCP Server.
- The Domain Name Service (DNS) resolves domain names to IP addresses.

Note: A server could provide multiple network services. For instance, a server could be an email, FTP and SSH server.

These network protocols comprise the fundamental toolset of a network professional, defining:
- Processes on either end of a communication session.
- Types of messages.
- Syntax of the messages.
- Meaning of informational fields.
- How messages are sent and the expected response.
- Interaction with the next lower layer.
Many companies have established a policy of using secure versions (e.g., SSH, SFTP, and HTTPS) of these protocols whenever possible.

Businesses today are increasingly using IP telephony and streaming media to communicate with customers and business partners, as well as enabling their employees to work remotely.
The network administrator must ensure the proper equipment is installed in the network and that the network devices are configured to ensure priority delivery.
The factors that a small network administrator must consider when supporting real-time applications:
- Infrastructure – Does it have the capacity and capability to support real-time applications?
- VoIP – VoIP is typically less expensive than IP Telephony, but at the cost of quality and features.
- IP Telephony – This employs dedicated servers form call control and signaling.
- Real-Time Applications – The network must support Quality of Service (QoS) mechanisms to minimize latency issues. Real-Time Transport Protocol (RTP) and Real-Time Transport Control Protocol (RTCP) and two protocols that support real-time applications.

Topic Title	Topic Objective
Devices in a Small Network	Identify the devices used in a small network.
Small Network Applications and Protocols	Identify the protocols and applications used in a small network.
Scale to Larger Networks	Explain how a small network serves as the basis of larger networks.
Verify Connectivity	Use the output of the ping and tracert commands to verify connectivity and establish relative network performance.
Host and IOS Commands	Use host and IOS commands to acquire information about the devices in a network.
Troubleshooting Methodologies	Describe common network troubleshooting methodologies.
Troubleshooting Scenarios	Troubleshoot issues with devices in the network.

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