BCENT - Basic Cisco Entry Networking Technician

Chapter 3

Identifying Network Components

FOUNDATION TOPICS

•Media

•Network Infrastructure Devices

•Specialized Network Devices

•Virtual Network Devices

•Voice over IP Protocols and Components

IDENTIFYING NETWORK COMPONENTS

• What are the characteristics of various media types?

• What are the roles of different network components?

• What features are provided by specialized network devices?

• How is virtualization affecting network designs?

• What are the primary protocols and components in a VoIP network?

MEDIA

• Network media breaks down into three categories:

Copper

Fiber-optic

Wireless

•Each of these categories is divided into subcategories, each with different specifications and uses.

COPPER

• Copper cabling has been used for communication since the mid 1800’s when the telegraph became widely used.

• There are three categories of copper cabling:

Coaxial

Unshielded Twisted-pair

Shielded Twisted-pair

• Each also has subcategories with different specifications and uses.

COAXIAL CABLE

• Coaxial Cable (or coax for short) is composed of two conductors:

The inner, insulated conductor or center wire, passes the data.

The outer, braided metal shield, which helps protect the data.

COAXIAL CABLE TYPES

• The three of the most common types of coaxial cables are:

RG-6: Commonly used by local cable companies to connect individual homes.

RG-58: This type of coaxial cable was popular with early 10BASE2 Ethernet networks.

RG-59: Typical used to carry composite video between two nearby devices. (i.e. cable box to TV)

COAXIAL CABLE CONNECTORS

• The two common connector types used with coax are:

BNC F-connector

TWISTED PAIR CABLING

• The most popular physical LAN media type is twisted pair cable.

• In each cable there are eight individually, insulated strands of copper wire. Each pair of wire is twisted together to reduce EMI.

• There are two categories of twisted pair:

Unshielded Twisted Pair (UTP)

Shielded Twisted Pair (STP)

Unshielded Twisted Pair

• Category 6 Cable

• Four pairs of insulated copper wires

• Some resistance to EMI

Shielded Twisted Pair

• Category 7 cable

• Four pairs of insulated copper wires

• Each pair is wrapped in foil. All four pairs are wrapped in wire mesh

• Very resistant to EMI

TWISTED PAIR CATEGORIES

Category MaximumThroughput

Maximum Distance

Cat 3 10 Mbps 100 meters

Cat 5 100 Mbps 100 meters

Cat 5e 1 Gbps 100 meters

Cat 6 1 Gbps 100 meters

Cat 6a 10 Gbps 100 meters

Cat 7 10 Gbps 100 meters

Twisted Pair Connectors: RJ-45

• 8 pin connector

• Used on almost all Ethernet networks

Twisted Pair Connectors: RJ-11

• 4 pin connector

• Used on most home telephone networks

Twisted Pair Connectors: DB-9

• Also known as RS-232

• 9 pin connector

• Commonly used to connect the serial port on a computer to a networking device

FIBER-OPTIC CABLING

• Uses light from an LED or LASER to transmit information through a glass fiber.

• Two categories of fiber-optic cabling:

Multimode fiber

Single-mode fiber

Multimode Fiber (MMF)

• Core size: 62.5 microns

• Common uses:

Routers to switches

Switches to switches

Servers to switches

MULTIMODE FIBER (MMF)

Light propagation over multimode fiber-optic cable

Single-mode Fiber (SMF)

• Core Size: 10 microns

• Common uses:

Routers to switches

Switches to switches

SINGLE-MODE FIBER (SMF)

Light propagation over over single-mode fiber-optic cable

FIBER-OPTIC CONNECTORS

LC - Lucent connector

SC – Subscriber Connector ST – Straight Tip Connector

MTRJ – Mechanical Transfer-

Registered Jack

Fiber-Optic Compared to Copper

Advantages Of

Fiber-Optic Cabling

Higher bandwidth

Longer distances

Immune to EMI

Better security

Advantages of

Copper Cabling

Less expensive

Easy to install

Inexpensive tools

CABLE DISTRIBUTION

• Components

Entrance facilities

MDF (main distribution frame)

Cross-connect facilities

IDF (intermediate distribution frame)

Backbone wiring

Telecommunications closet

Horizontal wiring

Work area

CABLE DISTRIBUTION

TIA/EIA structured cabling in a building

CABLE DISTRIBUTION

66-block patch panel 110-block patch panel

CABLE DISTRIBUTION

A typical UTP cabling installation

WIRELESS TECHNOLOGIES

All devices connected to the same AP are considered to be on the same shared network segment.

NETWORK INFRASTRUCTURE DEVICES

• There are two primary categories of network infrastructure devices:

Switches

Routers

• In order to understand how switches work, it is important to learn how they evolved from two older technologies: Hubs and Bridges

HUBS

• Hubs operate at Layer 1 of the OSI model and were used to connect multiple network devices.

• They are sometimes called multiport repeaters.

• Three basic types of Ethernet hubs:

Passive Hub

Active Hub

Smart Hub

• Hubs are essentially obsolete today. They have been replaced by switches in modern LANs.

Hubs

• One collision domain

• One broadcast domain

BRIDGES

• Join two or more LAN segments.

• Each LAN segment becomes a separate collision domain.

• Bridges analyze source MAC addresses in frames entering the bridge and populate an internal MAC address table based on those addresses.

• Bridges make intelligent forwarding decisions based on the destinationMAC address in the frame.

BRIDGES

Two Collision Domains

One Broadcast Domain

SWITCHES

• Switches are essentially a multiport bridge. They are usually considered a Layer 2 device.

• They learn MAC addresses and make forwarding decisions based on that information.

• Switches analyze source MAC addresses in frames entering the switch and populate an internal MAC address table based on those addresses.

• Each port represents a collision domain. All ports belong to the same broadcast domain

Switches

• Four collision domains

• One broadcast domain

ROUTERS

• Routers are Layer 3 devices. They make forwarding decisions based on logical network address information, usually IP addresses.

• Each port on a Router is a separate collision domain AND a separate broadcast domain.

• Routers are typically more feature-rich and support a broader range of interface types.

ROUTERS

Eight Collision Domains

Two Broadcast Domains

MULTILAYER SWITCHES

• Multilayer switches combine features of Layer 2 Switches and Layer 3 Routers.

• They can make decisions based on both MAC addresses and IP addresses.

• If configured with VLANs (which will be discussed in Chapter 4) each port on a multilayer switch can be a collision domain AND a broadcast domain.

Multilayer Switches

• Multilayer switch configured with virtual LANs (VLANs)

• Four collision domains

• Four broadcast domains

INFRASTRUCTURE DEVICES SUMMARY

Device Type Number ofCollision DomainsPossible

Number of Broadcast DomainsPossible

OSI Layer of Operation

Hub 1 1 1

Bridge 1 per port 1 2

Switch 1 per port 1 2

Multilayer Switch 1 per port 1 per port 3+

Router 1 per port 1 per port 3+

SPECIALIZED NETWORK DEVICES

• There is more to a network than just routers, switches and PCs. Other devices serve specific functions to improve network usability, performance and security.

• Some of these devices are:

VPN Concentrators

Firewalls

DNS Servers

DHCP Servers

Proxy Servers

Content Engines and Switches

VPN CONCENTRATORS

• Companies with locations across multiple sites require secure communications between those sites.

• A Virtual Private Network (VPN) creates a secure, virtual tunnel network over an untrusted network, like the Internet.

• One of the devices that can terminate VPN tunnels, is a VPN Concentrator, although firewalls typically perform this function now.

• There will be more about VPNs in Chapter 12.

VPN CONCENTRATORS

VPN

Concentrator

VPN

Concentrator

VPN

Concentrator

VPN

Concentrator

Headquarters

Branch A

Branch B

Branch C

FIREWALLS

• A firewall is primarily a network security appliance. It stands guard at the entrance to your network, protecting it from malicious Internet traffic.

• Firewalls can be software or hardware.

FIREWALLS

DNS SERVERS

• Computers and the internet use numbers not names, but people recall names better than numbers.

• A Domain Name System (DNS) server performs the task of taking a domain name like, www.ciscopress.com and resolving that name into an IP address that is understood on the network.

• This is similar to the contact list on your phone. You rarely dial your best friend’s phone number. You just click their name to call them.

DNS SERVERS

DNS HIERARCHY

Root

.com .mil .edu

cisco amazon twitter navy af army eku purdue yale

cs math

DHCP SERVERS

• Initially, clients on networks needed IP addresses manually configured (or statically assigned) in order to communicate. This was a hassle and also led to configuration errors.

• Dynamic Host Configuration Protocol (DHCP) automates the process so the vast majority of devices on a network receive an IP address automatically.

• The key elements assigned through DHCP are: IP address, subnet mask, default gateway and DNS server.

DHCP SERVERS

PROXY SERVERS

• A proxy server is a device that makes a request on behalf of a client.

• Clients are configured to forward their packets, which are seemingly destined for the Internet, to a proxy server.

• The proxy server evaluates the request, if it has a copy of the information the client is seeking, it replies with the cached copy.

• If the requested page is not in the cache, the server forwards the request to the Internet.

PROXY SERVERS

CONTENT ENGINES AND SWITCHES

• Some networks do not use proxy servers, instead they use a dedicated appliance to perform this content caching.

• These appliances are commonly referred to as caching engines or content engines.

• Content switches are also known as load balancers, distributing incoming requests across the various servers in the server farm.

CONTENT ENGINES

IP WAN

Req

ues

t

Content from the HQ server

is Sent to the Branch Office

Content Engine

Branch

Office

HQ

ServerContent

Engine

PC

Rep

ly

CONTENT SWITCHES

Internet

Server Farm

VIRTUAL SERVERS

• Instead of having several, separate, physical servers, virtualization allows multiple, virtual instances of servers to exist on a single, powerful server.

• A single server can have multiple Microsoft Windows virtual servers running simultaneously with Linux virtual servers.

VIRTUAL SERVERS

Microsoft

Windows Active

Directory

Linux Web

Server

Sun Solaris

DNS Server

Single

NICEthernet

Switch

Virtual Server

VOIP PROTOCOLS AND COMPONENTS

• A Voice over IP (VoIP) network, digitizes voice traffic so that it can be treated like other data on the network.

• A VoIP network can save a company money and provide enhanced services over a traditional PBX solution.

VOIP PROTOCOLS AND COMPONENTS

IP Phone

Analog

Phone

PBX

PSTN

IP WAN

SIP

SIP

SIP

SIP

RTP

Call Agent

GatewayGateway

Switch

SUMMARY

• OSI Reference Model Seven Layers

Assists in understanding network processes

•TCP/IP Stack Four Layers

Similar purpose as OSI model

• Port Numbers and Assignments Each application layer protocol has a different port number

Different ranges have different purposes

SUMMARY

• Media

Copper

Fiber-optic

Wireless

• Network Infrastructure Devices

Switches

Routers

SUMMARY

• Specialized Network Devices VPN Concentrators

Firewalls

DNS Servers

DHCP Servers

Proxy Servers

Content Engines and Switches

• Virtual Network Devices Virtual Servers

• Voice over IP Protocols and Components