1.2 Network Documentation

Question 1

1.2.1 Documentation Overview

Answer 1

Accurate and complete network documentation is required to effectively monitor and troubleshoot networks.

Common network documentation includes the following:

Physical and logical network topology diagrams
Network device documentation that records all pertinent device information
Network performance baseline documentation
All network documentation should be kept in a single location, either as hard copy or on the network on a protected server. Backup documentation should be maintained and kept in a separate location.

Question 2

1.2.2 Network Topologies and Descriptions

Question 3

PAN

Answer 3

A personal area network (PAN) is a network that connects devices, such as mice, keyboards, printers, smartphones, and tablets within the range of an individual person. These devices are most often connected with Bluetooth technology. Bluetooth is a wireless technology that enables devices to communicate over short distances.

Question 4

LAN

Answer 4

Traditionally, a local area network (LAN) is defined as a network that connects devices using wire cables in a small geographical area. However, the distinguishing characteristic for LANs today is that they are typically owned by an individual, such as in a home or small business, or wholly managed by an IT department, such as in a school or corporation.

Question 5

VLAN

Answer 5

Virtual LANs (VLANs) allow an administrator to segment the ports on a single switch as if it were multiple switches. This provides more efficient forwarding of data by isolating traffic to only those ports where it is required. VLANs also allow end devices to be grouped together for administrative purposes. In the diagram, VLAN 2 creates a virtual LAN for IT’s computers, even on different floors, and can have different network permissions set than the other VLANs.

Question 6

WLAN

Answer 6

A wireless LAN (WLAN) is similar to a LAN but wirelessly connects users and devices in a small geographical area instead of using a wired connection. A WLAN uses radio waves to transmit data between wireless devices.

Question 7

WMN

Answer 7

A wireless mesh network (WMN) uses multiple access points to extend the WLAN. The topology shows a wireless router. The two wireless APs extend the reach of the WLAN within the home. Similarly, businesses and municipalities can use WMNs to quickly add new areas of coverage.

Question 8

CAN

Answer 8

A campus area network (CAN) is a group of interconnected LANs, belonging to the same organization and operating in a limited geographical area. These can be both academic campuses and business or corporate campuses. Campus area networks typically consist of several buildings interconnected by high-speed Ethernet links using fiber optic cabling.

Question 9

MAN

Answer 9

A metropolitan area network (MAN) is a network that spans across a large campus or a city. The network consists of various buildings connected through wireless or fiber optic media.

Question 10

WAN

Answer 10

A wide area network (WAN) connects multiple networks that are in geographically separated locations. Individuals and organizations contract for WAN access from a service provider. Your service provider for your home or mobile device connects you to the largest WAN, the internet.

Question 11

VPN

Answer 11

A virtual private network (VPN) is used to securely connect to another network over an insecure network, such as the internet. The most common type of VPN is used by teleworkers to access a corporate private network. Teleworkers are network users that are offsite or remote. In the figure, the fat links between Teleworker 1 and the router at the Company Headquarters represent a VPN connection.

Question 12

1.2.4 Enterprise Network Topologies

Answer 12

PHYSICAL TOPOLOGY: The topology identifies the physical location and function of the devices.
LOGICAL TOPOLOGY: displays connecting interfaces and the Layer 3 network addressing scheme.

Different topology diagrams may include:

Physical layout and connections
IP address and VLAN management
Security and VPN policies
Cloud services and management
Routing policies
Remote access policies for remote and hybrid workers

Question 13

1.2.5 Network Cloud Services and Applications

Answer 13

XaaS (Anything/Everything as a Service)

SaaS - Software as a Service
PaaS - Platform as a Service
IaaS - Infrastructure as a Service

Disaster recovery as a service (DRaaS)
Communications as a service (CaaS)
Monitoring as a service (MaaS)
Desktop as a service (DaaS)

Question 14

1.2.6 Wireless Standards

Answer 14

The best place to start is with the IEEE 802.11 WLAN standards. These standards define how radio frequencies are used for wireless links. Most of the standards specify that wireless devices have one antenna to transmit and receive wireless signals on the specified radio frequency (2.4 GHz, 5 GHz or 6 GHz). Some of the newer standards that transmit and receive at higher speeds require access points (APs) and wireless clients to have multiple antennas using the multiple-input and multiple-output (MIMO) technology. MIMO uses multiple antennas as both the transmitter and receiver to improve communication performance. Up to eight transmit and receive antennas can be used to increase throughput.

Various communications channels transmit signals over the electromagnetic spectrum. The licensed spectrum refers to the bands (range of frequency) that are reserved for radio stations, cellular companies, and broadcast television stations. Media and cellular companies typical pay for the right to transmit over a specific frequency within the licensed spectrum. In the United States, this is done by the Federal Communications Commission (FCC). Other countries have a similar regulatory agency which licenses specific bands for that country.

The unlicensed spectrum is open for anyone to use. The unlicensed spectrum is where we find IEEE 802.11 Wi-Fi technologies and is available free to the public. Anyone can transmit over the unlicensed spectrum.

Question 15

1.2.8 Network Device Documentation

Answer 15

Network device documentation should contain accurate, up-to-date records of the network hardware and software. Documentation should include all pertinent information about the network devices.

Many organizations create documents with tables or spreadsheets to capture relevant device information.

Question 16

1.2.9 Establish a Network Baseline

Answer 16

The purpose of network monitoring is to watch network performance in comparison to a predetermined baseline. A baseline is used to establish normal network or system performance to determine the “personality” of a network under normal conditions.

Establishing a network performance baseline requires collecting performance data from the ports and devices that are essential to network operation.

A network baseline should answer the following questions:

How does the network perform during a normal or average day?
Where are the most errors occurring?
What part of the network is most heavily used?
What part of the network is least used?
Which devices should be monitored and what alert thresholds should be set?
Can the network meet the identified policies?
Measuring the initial performance and availability of critical network devices and links allows a network administrator to determine the difference between abnormal behavior and proper network performance as the network grows or traffic patterns change. The baseline also provides insight into whether the current network design can meet business requirements. Without a baseline, no standard exists to measure the optimum nature of network traffic and congestion levels.

Analysis after an initial baseline also tends to reveal hidden problems. The collected data shows the true nature of congestion or potential congestion in a network. It may also reveal areas in the network that are underutilized, and quite often can lead to network redesign efforts, based on quality and capacity observations.

The initial network performance baseline sets the stage for measuring the effects of network changes and subsequent troubleshooting efforts. Therefore, it is important to plan for it carefully.

Question 17

1.2.10 Cisco Discovery Protocol (CDP) Overview

Answer 17

CDP is a Cisco proprietary Layer 2 protocol that is used to gather information about Cisco devices which share the same data link. CDP is media and protocol independent and runs on all Cisco devices, such as routers, switches, and access servers.

The device sends periodic CDP advertisements to connected devices.

These advertisements share information about the type of device that is discovered, the name of the devices, and the number and type of the interfaces.

Because most network devices are connected to other devices, CDP can assist in network design decisions, troubleshooting, and making changes to equipment. CDP can also be used as a network discovery tool to determine the information about the neighboring devices. This information gathered from CDP can help build a logical topology of a network when documentation is missing or lacking in detail.

Question 18

1.2.11 Discover Devices Using CDP

Answer 18

With CDP enabled on the network, the show cdp neighbors command can be used to determine the network layout.

The show cdp neighbors command provides helpful information about each CDP neighbor device, including the following:

Device identifiers - This is the host name of the neighbor device.
Port identifier - This is the name of the local and remote port.
Capabilities list - This shows whether the device is a router or a switch
Platform - This is the hardware platform of the device.