Chapter 10: Implementing Network Services and IP Operations

The Cisco IOS operating system is filled with many features that we are yet to explore. The operating system contains a wide variety of network services that are designed to provide scalability and flexibility on a network; these features are commonly referred to as IP services. IP services are the essential services each network needs, such as the Dynamic Host Configuration Protocol (DHCP) to assist with the automatic assignment of IP addresses to client devices, the Domain Name System (DNS) to resolve hostnames to IP addresses, and even network monitoring and management protocols to provide accountability and visibility on a network.

During the course of this chapter, you will learn how to implement the Network Time Protocol (NTP) to ensure all devices' clocks are synchronized and that proper timekeeping is maintained on a network. You'll learn how to implement DHCP on a Cisco system to distribute IP configurations...

Technical requirements

To follow along with the exercises in this chapter, please ensure that you have met the following software requirement:

• Cisco Packet Tracer: https://www.netacad.com

The code files for this chapter are available at https://github.com/PacktPublishing/Implementing-and-Administering-Cisco-Solutions/tree/master/Chapter%2010.

Check out the following video to see the Code in Action: https://bit.ly/3mKumGp

Understanding NTP

Time...what an important role it plays in our daily lives. From helping us measure how long it takes us to arrive at a destination or event to calculating how quickly athletes perform at the Olympic games. Time is simply the measurement between past, present, and future events.

Time is used to help us take account of an event. Timestamps are used on electronic devices, surveillance systems, and computer and networking devices to provide an account of when certain actions and events occur. On an enterprise network, it is critical to ensure proper timekeeping is maintained throughout the organization.

Why is timekeeping a critical factor on a network? Ensuring all devices are configured with accurate time is important for log and event management on an enterprise network. Events occur frequently on networks; in all the labs you've completed thus far, when you make a change on a Cisco device, a Syslog message is generated and presented on the console window...

Understanding DHCP

On any computer network, there are many end devices, network intermediary devices, and even servers. Each device requires an IP address to exchange messages and share resources with each other. A network administrator usually assigns static IP addresses to devices that provide a service or resource to the network – devices such as switches, routers, firewalls, and servers. When a device is assigned a static IP address, it allows network administrators to remotely access and manage the device, as the address will never change.

Since a network is mostly made up of a computer and other end devices that often change physical locations, it's not wise to always assign static IP addresses to such devices. When a device with a static IP address is moved to another location, whether physical or logical, the IP scheme at the new location may not be the same as the IP configurations on the device itself. Therefore, the network administrator will be required to...

Domain Name System

Let's imagine you want to research additional information about the Cisco Certified Network Associate (CCNA) certification. The best place to start researching would be Cisco's website at www.cisco.com. Open your favorite web browser and simply enter the URL into the address bar and hit Enter. After a few seconds, the Cisco website appears and you can continue your research. Everything seems to work like magic, but have you ever wondered how your computer determines the IP address for the web server that is hosting Cisco's website?

As mentioned in Chapter 3, IP Addressing and Subnetting, each device that is connected and exchanging messages on a computer-based network must be assigned a unique IPv4 or IPv6 address. The same is also applied to all devices on the internet, such as web and mail exchange servers. If a web server is identified by its IP address, why does it have a website URL address such as www.cisco.com?

To help you understand the...

Understanding the benefits of using Syslog

When events occur on a network, networking devices, such as routers, switches, and firewalls, generate a log message to notify the administrator with details about the event. These log messages can contain details about critical or non-critical events. Network professionals use a wide range of tools and options for managing these log messages, such as storing, displaying, interpreting, and normalizing. This helps network professionals to focus on the more critical log messages and determine the timeline of an event that has occurred.

Syslog is both a protocol and standard for accessing, creating, and managing log messages on a computer and network device. Syslog defines the method of how system messages, such as logs, are generated, formatted, and accessed.

Important note

The Syslog log uses UDP port 514 to send event messages across a network to a centralized Syslog server for management.

Implementing proper log management on...

Simple Network Management Protocol

SNMP was designed to enable IT administrators to manage network and end devices, such as workstations, servers, switches, routers, and security appliances, easily on an IP-based network. SNMP provides the functionality to allow device administrators to monitor, manage, and troubleshoot network performance.

SNMP is made up of the following three components:

• SNMP manager
• SNMP agent
• Management Information Base (MIB)

These three components all work together to create a Network Management System (NMS). The SNMP manager is the application that is installed and running on the administrator's computer. The SNMP manager is responsible for collecting the information from the SNMP agents using SNMP GET messages. The manager is able to make modifications to the network device's configuration by using SNMP SET messages.

The SNMP agent and MIB exist on the actual networking device, such as a switch or router. The SNMP agent...

QoS traffic classification

Let's imagine the roadways of a city do not widen automatically and if there are too many vehicles using the medium (roadways) and they are not exiting quickly enough, traffic starts accumulating and results in congestion. Therefore, each person may take a much longer time to reach their destination.

In a production environment, you're the network engineer for a very large organization with a lot of users and many network applications. Each day, users are simultaneously accessing both internal resources on the network, such as locally hosted applications, and external resources; there are tons of various traffic types that are traveling along the network each day. What would you do if users began experiencing an unacceptable user experience on the corporate network, such as very slow response times?

Each day, there are thousands and even millions of packets being generated by devices and they are sent with messages to another device as a...

Summary

In this chapter, we covered a wide array of IP services that are crucial for improving the efficiency of an enterprise network. You learned about the importance of proper timekeeping and how to implement NTP to ensure devices' system clocks are synchronized. Furthermore, you saw the benefits of implementing DHCP on a network to automatically distribute IP addresses to end devices and DNS to help resolve hostnames to IP addresses easily.

Next, you saw how network management protocols such as SNMP can be used to help network engineers to easily monitor and manage network devices, and Syslog can be used to improve log management using a centralized logging server. Lastly, you gained an insight into the difference that QoS can make on a network.

I hope this chapter has been informative for you and is helpful in your journey toward learning how to implement Cisco solutions and prepare for the CCNA 200-301 certification. In the next chapter, Chapter 11, Exploring Network...

Questions

The following is a short list of review questions to help reinforce your learning and identify areas that require some improvement:

1. What is the default port for NTP?

   A. 143

   B. 110

   C. 123

   D. 1234

2. Which command allows you to configure the system clock on a device?

   A. ntp server

   B. ntp master 1

   C. ntp master

   D. clock set

3. Which Stratum level has the most accurate time on a network?

   A. 0

   B. 4

   C. 1

   D. All

4. DHCP has which of the following open ports?

   A. 68

   B. 67

   C. 69

   D. 53

5. After a DHCP server receives a DHCP request message, what message will the server send to the client?

   A. None

   B. Discover

   C. Acknowledgement

   D. Offer

6. Which DNS record is used to resolve an IP address to a hostname?

   A. SOA

   B. MX

   C. A

   D. PTR

7. Syslog uses which of the following ports?

   A. 123

   B. 161

   C. 512

   D. 514

8. Which port does SNMP use?

   A. TCP 123

   B. UDP 161

   C. TCP 161

   D. UDP 514

9. Which SNMP message is used to modify a device's configuration?

   A. Set

   B. Trap

   C. Get

   D. Create

10. Which of the following is the...

Further reading

The following links are recommended for additional reading:

• Configuring NTP: https://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/5_x/nx-os/system_management/configuration/guide/sm_nx_os_cg/sm_3ntp.html
• Configuring DHCP: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_dhcp/configuration/xe-3se/3850/dhcp-xe-3se-3850-book/config-dhcp-server.html
• Configuring DNS: https://www.cisco.com/c/en/us/support/docs/ip/domain-name-system-dns/24182-reversedns.html
• Configuring Syslog: https://www.cisco.com/c/en/us/td/docs/routers/access/wireless/software/guide/SysMsgLogging.html
• Configuring SNMP: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/snmp/configuration/xe-16/snmp-xe-16-book/nm-snmp-cfg-snmp-support.html
• Configuring QoS: https://www.cisco.com/c/en/us/td/docs/routers/access/800M/software/800MSCG/QoS.html