• UDP Is a connectionless protocol. UDP is used if data packets do not require guaranteed delivery .
• The TCP & UDP protocols use port numbers to map data packets to a specific application , or process that is running on a server.
• TCP and UDP ports enable network servers to quickly & reliably respond to many simultaneous requests for data that are initiated by and destined to separate applications.

• The native TCP/IP naming system relies on a file called a HOSTS file & contains the name & IP address of known hosts.

• DNS is a hostname resolution system that solves the shortcomings of the HOSTS file for name resolution.
• The structure of DNS is Hierachial and DNS database files are distributed among root, top level domains, second level domains, and subdomains.

• Dynamic Updates enable DNS client computers to register and dynamically update their resource records with a DNS server whenever changes ocur.

• DNS zones can be either Forward lookup, or Reverse lookup zones. They can also be either a primary or secondary zones.

• Many ISPs offer caching-only DNS servers.
• An organization may run its own DNS Server that can either point to the caching-only server or directly to the root server for name resolution.

• The most common services that are used on the internet include: FTP, FPTS, SMTP, POP3, IMAP4, HTTP and HTTPS.
• HTTP and HTTPS are used for web server services; HTTPS is a secure version of HTTP which uses SSL.
• An ISP supports HTTPS by providing high-performance web servers to support HTTPS encryption and decryption demands.

• FTP is used for file transfer services. The ISP can support active and passive FTP connections. Active connections require the server to initiate the connection. Passive connections require the host to initiate the connection.
• Email uses 3 Different protocols. SMTP is used to send email. POP3 and IMAP are both used to retrieve email.

• The Internet is divided up into collections of networks called Autonomous systems.
• Within an Autonomous system, Interior gateway routing protocols are used, such as RIP, EIGRP and OSPF.
• Between Autonomous systems, exterior gateway functions are required. Exterior Gateway Protocols (EGPs) run on exterior routers, on border gateways, that are located at the border of an AS (autonomous system). The most common EGP is Border Gateway Protocol (BGP).

• BGP functions like a distance-vector protocol. From this database, direction and distance to a destination network are determined.
• Exterior protocols enable traffic to be routed across the internet to remote destinations.
• Exterior protocols provide the method by which ISPs can set and enforce policies and local preferences for traffic flow efficiency.

The Key Components on a Cisco 1841 ISR are:

• HWIC slots
• Compact Flash Module
• USB port
• Dual 10/100 fast Ethernet ports
• Console and auxiliary ports
• System Power LED
• Cisco IOS software image

• The Router bootup process has 3 Stages:

1. Performing the P.O.S.T (Power On Self Test)
2. Locating and Loading the IOS Software
3. Locating and executing the startup configuration file

• There are 2 possible methods to connect a PC to a network device for configuration and monitoring tasks, in-band and out-of-band management.

• Cisco Router and Security Device Manager (SDM) is a graphical user interface (GUI) tool that can be used to configure. monitor, and maintain Cisco devices. Cisco SDM is the recommended way to configure a new Cisco ISR.

• The Cisco IOS Command Line Interface (CLI) is a text-based program that enables the entering and executing of Cisco IOS commands to configure, monitor and maintain Cisco devices. The Cisco IOS CLI is used for the advanced configuration of Cisco devices and to configure Older devices that do not support SDM.

• The Configuration Checklist Job aid is an important tool to help ensure that the Customer gets the configuration that they want.

• SDM Express is a tool bundled within the Cisco Router and Security Device Manager that makes it easy to create a basic router configuration.
• SDM is a more advanced GUI interface with more configuration options available.
• Both SDM and SDM Express use GUI-based Configuration Wizards to simlify the configuration of the Cisco devices.
• Some of the features that can be configured include:

1. Basic Configuration
2. LAN IP configurations
3. DHCP
4. WAN IP Configurations
5. NAT

• The CLI does not provide step-by-step configuration assistance, therefore it requires more planning and expertise to complete.
• The privileged exec, global config and interface modes are all used when configuring a router using the Cisco IOS CLI.
• Context-sensitive help can provide suggestions for completing a command as well as determining additional command parameters.

• The IOS show commands are a fundamental tool for verifying and troubleshooting router configurations.
• The startup configuration file is stored on the device in NVRAM and is loaded into working memory and begins device operation.
• The running configuration is the set of commands that is currently active in the device RAM.
• IOS CLI can be used to configure basic router setting, Including router name, password and banners. It can also be used to configure serial and Ethernet interfaces, DHCP and NAT.

• A WAN connection is a type of network connection that can send a network signal over long distances.
• There are 3 types of serial WAN connections:

1.  Point to Point
2. Circuit Switched
3. Packet Switched

• Choosing the correct WAN involves planning and consideration.
• Cisco devices can be configured remotely across a WAN connection using : Telnet or SSH, SSH is the preferred method.
• Some WAN connections support Ethernet interfaces. Other WAN connections support serial interfaces.

• The Key components of a Cisco Catalyst 2960 Series Switch are:
• 24 x 10/100 Ethernet ports
• Port Status LEDs
• Mode button
• Console port
• Dual Purpose 10/100/1000 or SFP port
• Cisco IOS LAN-based Software Image

• The 2960 supports port autonegotiation of duplex and speed.

• When configured with an IP Address, interface VLAN 1 allows you to remotely manage the switch using SSH or other TCP/IP applications such as Network management software.
• A Basic Switch configuration includes  switch name and encrypted passwords used to access the switch and the Cisco CLI configuration commands.
• Port Security limits the number of valid MAC Addresses allowed per port and can be configured statically, dynamically or dynamic sticky.

PLANNING THE ADDRESSING STRUCTURE

• Interfaces on network devices connected to the Internet need to have a unique IP address, to send and recieve messages over internetworks.
• IP Addresses are organised into Network Classes, A – B – C -D & E. And are conserved by the creation of private IP address space.
• A Network can be divided into Subnets.
• Classful subnetting uses the extension of the subnet mask. Classless IP Addressing, part of  a method called, classless inter – domain routing (CIDR) uses a flexible method of subnetting, with variable length subnet masks (VLSM).
• Subnet masks allow further subdivision of networks by extending the number of bits used.
• A Subnet ID is created by splitting the host ID into 2 parts, A subnet ID and a new host ID.
• The number of bits in the Subnet ID determines the number of subnets there can be in a network.
• Communication betwwen subnets requires routing.

• NAT enables a large group of private users to access the internet by sharing a small pool of public IP addresses, therefor reducing the consumption of globally unique IP addresses.
• Inside Addresses are IP Addresses  for private Network devices. Outside Addresses are IP Adddresses for public Network devices. Local Addresses are IP Addresses in packets that are still in the private network. Global Addresses are IP Adddresses that cross  to the Outside network.
• A packet that has been translated and is in the outside network  will list an inside – global IP addresss as source and an outside global IP address  as destination.
• Static NAT is for permanent one-to-one translations from a specific inside-local IP Address to a specific inside-global IP Address.
• Dynamic NAT assigns inside – global IP Addresses on a first – come, first servered basis from an available pool of IP addresses to a designated network or sub-network.
• PAT, can be used to add a port number to the IP addresses for specific connections.
• Network devices that use NAT translate Addresses on every packet. This can significally increase processing work load.
• IPv6 incorporates a 128 - bit addressing scheme, whereas IP v4 uses 32 – Bits.

• If a Network Upgrade is necessary, a Plan should be in place, With Considerations to strengths, Weaknesses, oppurtunities, or threats (SWOT) of the network installation.
• There are 5 phases of a network upgrade:

1. Requirements gathering
2. Selection and Design
3. Implementation.
4. Operation.
5. Review and evaluation.

• Examine the network facilities includes the physical environment, the telecomunications rooms (MDF & IDF) as well as existing network (media) wiring.
• When Cabling there are 4 physical areas to consider:

1. Work area.
2. Distrubution area.
3. Telecommunications room area.
4. Backbone Area.

• When determining cabling needs, it is necessary to keep in mind the work area, the type of cable used and the purpose of the cable.
• Structured cabling projects deal with the placement of cables, the location of wiring closets, cable management, and electrical considerations.
• When new equipment is used for network upgrade, there are 2 purchace options:

1. Managed Service.
2. In – house customer purchaced.

• A device that functions at higher OSI layers is generally considered a more intelligent device.
• When Upgrading Network Devices, Costs and scaleability are important factors to consider.

• Help Desk Technicians provide solutions to customers’ network problems.
• User Support usually exists in 3 Levels: Tier 1, 2 and 3.
• Incidident management is the basic procedure, followed when a help desk technition initiates the standard problem solving processers.
• Help Desk operation relies on opening trouble tickets and logging details.
• Customer service and interpersonal skills are important when handling difficult clients and incidents.
• Skills required by Help desk technicians for successful communication include:

1. Preperation
2. Courteous greeting
3. Listening to the customer
4. Adapting to customer temprament.
5. correctly diagnosing a simple problem.
6. Logging the call.

A Layered approch is best used in troubleshooting.

The OSI Model is best used to identify a problem.

The OSI Model breaks down the task of Network communications into multiple processers. each process is a small part of the larger task.

The 7 Layers of the OSI referance model can be broken down to 2 parts: Upper layer and Lower layer

Upper Layers consist of Any layer above the transport layer and are implemented in Software.

Lower Layers consist of the Transport, Network, Data link and Physical layers and handle data transport functions.

Using the OSI model, the help desk technician can troubleshoot using: Bottom – up, Top Down, or divide-and -conquer approaches.

Some of the most common customer service call, are about email and connectivity issues.

Information gathered from the customer is transfered to the Trouble ticket.

• Level 1 & Level 2 , help desk technicions attempt to solve customer issues over the phone, web or remote desktop sharing applications.
• Sometimes it is necessaryto dispatch a level 3 On – Site technician.
• It is important to document the solution on the customer work order, the trouble ticket and an In – Knowledge- Base document for future referance.

Many Businesses use the Internet for E- Commerce, communictions and Colaboration and Training.

Networking and Internet standards ensure that all devices connecting to the network use the same set of rules.

By having a set of rules it is possible for different types of devices to send information to each other over the internet. 

Regardless of the type of device that an individual business wants to use to connect to the Internet, the device must connect through an Internet service provider (ISP).

In addition to offering connection to the Internet an ISP can offer services such as equipment co-location, Web hosting,  FTP hosting,  Technical Support, Voice over IP (VoIP), applications and media hosting.

Larger businesses typically require more higher bandwidths, and faster connections such as – T1 / E1, T3 / E3 and Metro Ethernet. 

The ISP POP‘s connect to an Internet exchange point (IXP), a point where multiple ISP’s join together to gain access to each others networks and exchange information. 

The Internet Backbone is made up of a group of networks owned by various organisations and Interconnected through IXP‘s and private peering connections.

ISP’s are classified as Tier 1, Tier 2 and Tier 3 depending on how they connect to the Internet Backbone.

An ISP requires a number of devices to accept input from end users and provide services, including access devices border gateway routers, high end Air conditioning units & Power conditioning equipment.

The ISP provides a reliable & Scaleable Network.

A scaleable network can expand quickly to support new users and applications without impacting current performance.

ISP Organisations are made up of many Teams & Departments that have the responsability of ensuring the smooth operation of the Network.

ISP Network support teams can include: Customer service team, a NOC team, an On-Site team, a Planning and Provisioning team, & the Help desk team. 

This Chapter discussed the process of identifying, locating and correcting problems that occur witin a Network.

• Gathering Information and Verifying that the problem exists are important first steps in the troubleshooting process.
• When Troubleshootng, there are several structured troubleshooting techniques that can be used including:

• Top Down -

1. How it operates – Always starts at the application layer and works its way down until it finds a faulty layer.
2. Cases for which it is suitable - More suitable for simpler problems not those that are suspected to be application/user or upper-layer related.
3. Advantages / Disadvantages – If the problem turns out to be related to lower layers, you have wasted a lot of time and effort at the upper or application layers.

• Bottom Up -

1. How it operates -
   Always starts at the physical layer and works its way up until it finds a faulty layer.
2. Cases for which it is suitable – More suited for complex cases.
3. Advantages / Disadvantages. – It is a slow, but solid approach. When the problem is application (or upper layer) related, this approach can take a long time.

• Divide -and-Conquer -

1. How it operates - Based on the circumstances (reported issues) and your experience, you might decide to start at any layer and work up or down the OSI stack.
2. Cases for which it suitable - Most suitable when you are experienced and the problem has precise symptoms.
3. Advantages / Disadvantages – It approaches the layer of the culprit faster than the other approaches.
   You need experience to use this approach effectively.

• Less Structured techniques include Trial-and-error and substitution.
• Experienced troubleshooters tend to rely on experience and less structured techniques for troubleshooting issues.

There are several tools available to help in the troubleshooting process.

• Physical problems are concerned mainly with the Hardware devices as well as Cabling Connections.
• Physical issues are commonly detected using the “Senses”.
• A number of software utillity programs are available that can help identify Network problems.
• Some of the most common software utilities used for troubleshooting include:

1. ipconfig
2. ping
3. tracert
4. nslookup
5. netstat

There are several issues to check when troubleshooting Wired and Wireless Networks.

• LED lights are used to indicate the current state or activity of a piece of equipment or connection.
• For wired devices, check Physical connectivity and cabling issues including: Wrong Cable Type, Bad termination, Physical damage and Port placement.
• For a Wireless Client, connectivity problems such as: A/B/G/N frequency compatibility, Overlapping channels, Signal Strength, and Interference should be examined. Also Check the  SSID, Authentication and encryption settings.
• On Both Wired and Wireless Clients check the IP Configuration of the client including the IP Address, Subnet Mask, Default Gateway and DNS Information .
• Verify connectivity between the ISR and the ISP by checking the Router Status Page in the ISR to ensure that an IP Address is assigned by the ISP and the connection is good.

There are Several sources of help when troubleshooting issues.

• Documentation such as Topology maps, Network Diagrams and Addressing schemes, assists with the troubleshooting effort.
• Outside resourses available to help with troubleshooting Include:  Previously kept documentation, Online FAQ’s, collegues and other Network Proffessionals, Internet Forums.
• A Helpdesk is a group of Individuals with the knowledge and tools required to help diagnose and correct common problems.
• 1st, 2nd and 3rd Level helpdesk support is often available with escalation procedures in place to try and help solve issues.
• It Is IMPORTANT to document all steps taken in the troubleshooting process, including interaction with the helpdesk.

Chapter discussed various Networking threats such as Information theft, Identity theft, Data loss and manipulation and disruption of service.

• Hackers are Intruders who gain access to a network through software vulnerabilities, hardware attacks or through the carelessness of network users.
• Attacks can come from both External and Internal sources, Internal attacks account for 70% of all security incidents.
• Social Engineering is a group of techniques designed to deceive internal users into performing specific actions or revealing confidential information.
• 3 types of Social Engineering attacks are: Pretexting, Phishing and Vishing.

There are other threats to the security of Computers and Networks, In addition to social Engineering Techniques.

• Viruses are programs that once activated spread by modifying other programs or files, causing damage to files, or erasing them completely.
• A Worm is similar to a virus except it runs independently and spreads by resending itself as an email attatchment or part of a network message.
• A Trojan horse is a program that appears legitimate. Once initiated, it can damage a hard drive or create a back door into a system allowing hackers to gain access.

Effective Network Security comes from a combination of products and services, combined with a thorough security policy and a commitment to adhere to that policy.

• A Security Policy should include: identification and authentication policies, password policies, acceptable use policies, remote access policies and incident handling procedures.
• All users of a network must support and follow the security policy in order for it to be effective.
• Tools and Applications used in securing a network include:

1. Software patches and updates.
2. Virus Protection.
3. Spyware Protection.
4. Spam Blockers.

A Firewall Controls the Traffic between Networks and helps prevent the Unauthorized Access. Firewall Products use various techniques for determining what is permitted or denied access to a network.

• Packet Filtering controls access based on IP and MAC addresses.
• Application / Web Site Filtering controls access based on the application.
• Stateful Packet Inspection (SPI) ensures incoming packets are legitamate responses to requests from internal hosts. SPI can recognize and filter out attacks such as Denial of Service (DoS).
• A Demilitorized Zone (DMZ) is an area of the Network that is accessable to both internal and external users.
• If the wireless access point is unsecured, anyone who connects to it is considered part of the internal network and is on the protected side of the firewall.
• Vulnerability analysis tools (security scanners) help identify areas where attacks might occur and offer guidence on steps that can be taken.

This Chapter described the varoius technologies for the transmission of  information between hosts without cables. This Chapter also describes the benifits and limitations of these wireless technologies and the devices that use them.

• Wireless technologies use electromagnetic radiation in the form of radio waves to carry infomation between devices.
• The most common wavelengths used for public wireless communications include infrared and part of the Radio Frequency Band (RF).
• Remote control devices, Wireless Mice, Wireless Keyboards use either Infrared Technology (IR) or Bluetooth technology.
• Devices such as Microwave ovens or cordless phones can interfear with WLAN‘s because of similar frequencies being used.

• Wireless Networks are grouped into 3 major catagories:

1. Wireless Personal Area Networks (WPAN)
2. Wireless Local Area Networks (WLAN) 
3. Wireless Wide Area Networks (WWAN)        

 The main organization responsible for the creation of the wireless technology standards is the  Institute of Electrical and Electronics Engineers.  (IEEE). Standards that govern the WLAN environment include : 802.11A , 802.11B, 802.11G and 802.11N (N is not yet ratified) all are known as wireless network standards or (WiFi).

WLANs

• Devices in a WLAN include: Wireless Clients, Access Points, Wireless Bridges and Antennas.
• A small WLAN, peer to peer network, is known as a ad- hoc network and does not include a Access Point (AP).
• Wireless devices use antennas to transmit and receive information, there are 2 types of antennas:

1. Directional
2. Omni – Directional

• All wireless devices in a WLAN must be configuered with the same  Service Set Identifier or (SSID) and operate using the same standards in order to communicate.
• To separate conversations, the (RF) spectrum is divided into different channels.
• AP‘s and Clients use and Acess method called Carrier Sense Multiple Access with Collision Avoidence (CSMA/CA) that creates a reservation on the channel for use by a specific conversation.

Because they can operate without much configuration and transmit information through the open air, wireless networks are more prone to attacks than Wired Networks:

• An Attacker can access your network from any location your wireless signal reaches.
• Attackers can use you Internet services for free or damage files or steal private information from your network.
• Basic Security measures that should be taken include :
• Change default Values of the SSID, usernames and Passwords.
• Disable the Broadcast SSID.
• Configure the MAC Address Filtering.
• More Advanced Security Measures that should be taken in a wireless Security plan would include:
• Configure Encryption using WEP and WPA or now WPA2 (more secure).
• Configure Authentication.
• Configure Traffic Filtering.

Before Installing a Wireless Network, an Installation plan should be created that includes the standards to be used, the location of devices, a security plan and a strategy for backing up configurations. In order to carryout this plan, the following steps are needed:

• Gather User Requirements to determine the appropriate standard to use, Bandwith requirements, coverage areas, existing implementations and COST.
• Perform a site survey to determine the optimum number and locations of AP‘s.
• Combine multiple Security techniques to strengthen the integrety of the wireless network.
• Perform a Full configuration Backup of wireless devices to provide a stored copy in case of  device failure.
• Upgrade Firmware, If necessary to take advantage of the enhancements to the Operating System.