Rangkuman CCNA Discovery 2 - Chapter 2

2.1.1 Help desk organization

                ISPs provide the Internet connection for businesses, and they provide their customers support for problems that occur with Internet connectivity. SP support is typically provided through the ISP help desk. Whether the problem is connecting to the Internet or getting email, the ISP help desk is usually the first place a user or business turns to for help.

                At an ISP, there are usually three levels of customer support:

1.            Level 1 is for immediate support handled by junior-level help desk technicians.

2.            Level 2 handles calls that are escalated to more experienced telephone support.

3.            Level 3 is for calls that cannot be resolved by phone support and require a visit by an on-site technician.

                In addition to ISPs, many other types of medium to large businesses employ help desk or customer support teams.

2.1.2 Roles Of ISP Technical

                When a user initially contacts the help desk to resolve an issue, the call or message is usually

directed to a Level 1 support technician. Level 1 support is usually an entry-level position that provides

junior technicians with valuable experience.

Many larger service providers have expanded their businesses to include managed services or

on-site support of a customer network. Organizations that provide managed services are sometimes referred to as Managed Service Providers (MSP).When an ISP is providing managed services, it often requires technicians to visit customer sites for the purpose of installation and support. This type of service represents Level 3 support.

                Level 3 support is usually in accordance with a Service Level Agreement (SLA). An SLA resembles an insurance policy, because it provides coverage or service if there is a computer or network problem.

2.1.3 Interacting whit customers

Help desk technicians may be required to provide phone support, email support, web-based

support, online chat support, and possibly on-site support. They are often the first point of contact for frustrated and anxious customers.

Help desk technician should be able to stay focused in an environment with frequent interruptions and perform multiple tasks efficiently and accurately. It can be difficult to consistently maintain a positive attitude and provide a high level of service. Help desk technician must have excellent interpersonal skills and effective communication skills, both oral and written. Technicians must be able to work independently and as part of a team.

help desk technicians must be able to greet customers pleasantly and be professional and courteous throughout the call. Opening trouble tickets and logging information on the tickets are critical to help desk operation. When there are many calls relating to a single problem or symptom, it is helpful to have information on how the problem was resolved in the past. It is also important to relay to the customer what is being done to solve the problem.

On the first visit to a customer location, it is important for the technician to make a good impression. Personal grooming and the way the technician is dressed are the first things the customer notices. If the technician makes a bad first impression, it may be difficult to change that impression and gain the confidence of the customer.

2.2.1  Using The OSI Model

When a network connectivity problem is reported to the help desk, many methods are available to diagnose the problem. One common method is to troubleshoot the problem using a layered approach. Moving data across a network is best visualized using the seven layers of the Open Systems Interconnection model, commonly referred to as the OSI model. The OSI model breaks network communications down into multiple processes. Each process is a small part of the larger task.

In a similar manner, the OSI model can be used as a means to focus on a layer when troubleshooting to identify and resolve network problems.

The seven layers of the OSI model are divided into two parts: upper layers and lower layers.

1.            The term upper layer is sometimes used to refer to any layer above the Transport layer of the OSI model. The upper layers deal with application functionality and are generally implemented only in software. The highest layer, the Application layer, is closest to the end user.

2.            The term lower layer is sometimes used to refer to any layer below the Session layer. The combined functionality of the lower layers handles data transport. The Physical layer and the Data Link layer are implemented in both hardware and software. The Physical layer is closest to the physical network medium, or network cabling. The Physical layer actually places information on the medium.

End stations, like clients and servers, usually work with all seven layers. Networking devices are only concerned with the lower layers. Hubs work on Layer 1, switches on Layers 1 and 2, routers on Layers 1, 2 and 3, and firewalls on Layers 1, 2, 3, and 4.

2.2.2 OSI Model Protocols And Technology

When using the OSI model as a framework for troubleshooting, it is important to understand which functions are performed at each layer, and what network information is available to the devices or software programs performing these functions. For example, many processes must occur for email to successfully travel from the client to the server. The OSI model divides the task of sending and receiving email into smaller, distinct steps that correspond with the seven layers.

Step 1: Upper layers create the data.

When a user sends an email message, the alphanumeric characters within the message are converted to data that can travel across the network. Layers 7, 6, and 5 are responsible for ensuring that the message is placed in a format that can be understood by the application running on the destination host. This process is called encoding. The upper layers then send the encoded messages to the lower layers for transport across the network. Transporting the email to the correct server relies on the configuration information provided by the user. Problems that occur at the application layer are often related to errors in the configuration of the user software programs.

Step 2: Layer 4 packet data for end-to-end transport.

The data that comprises the email message is packaged for network transport at Layer 4. Layer 4 breaks the message down into smaller segments. A header is placed on each segment indicating the TCP or UDP port number that corresponds to the correct application layer application. Functions in the transport layer indicate the type of delivery service. Email utilizes TCP segments, therefore packet delivery is acknowledged by the destination. Layer 4 functions are implemented in software that runs on the source and destination hosts.

Step 3: Layer 3 adds the network IP address information.

The email data received from the transport layer is put into a packet that contains a header with the source and destination network IP addresses. Routers use the destination address to direct the packets across the network along the appropriate path. Incorrectly configured IP address information on the source or destination system can cause Layer 3 problems to occur.

Step 4: Layer 2 adds the data link layer header and trailer.

Each network device in the path from the source to the destination, including the sending host, encapsulates the packet into a frame. The frame contains the physical address of the next directly-connected network device on the link. Each device in the chosen network path requires framing so that it can connect to the next device. Switches and network interface cards (NICs) use the information in the frame to deliver the message to the correct destination device. Incorrect NIC drivers, interface cards, and hardware problems with switches can cause Layer 2 problems to occur.

Step 5: Layer 1 converts the data to bits for transmission.

The frame is converted into a pattern of 1s and 0s (bits) for transmission on the medium. A clocking function enables the devices to distinguish these bits as they travel across the medium. The medium can change along the path between the source and destination. For example, the email message can originate on an Ethernet LAN, cross a fiber campus backbone, and cross a serial WAN link until it reaches its destination on another remote Ethernet LAN. Layer 1 problems can be caused by loose or incorrect cables, malfunctioning interface cards, or electrical interference.

At the receiving host, the processes described in steps 1 through 5 are reversed, with the message traveling back up the layers to the appropriate application.

2.2.3  trouble shooting the OSI model.

As a theoretical model, the OSI model defines the protocols, hardware, and other specifications that operate at the seven layers.

The OSI model also provides a systematic basis for troubleshooting a network. In any troubleshooting scenario, the basic problem-solving procedure includes the following steps:

1. Define the problem.

2. Isolate the cause of the problem.

3. Solve the problem.

In addition to the basic problem-solving procedures, the OSI model can be used as a guideline for troubleshooting. Using a layered model, there are three different troubleshooting approaches that a technician can use to isolate the problem:

Bottom-Up - The bottom-up approach starts with the physical components of the network and works its way up the layers of the OSI model. Bottom-up troubleshooting is an effective and efficient approach for suspected physical problems.

Top-Down - The top-down approach starts with the user application and works its way down the layers of the OSI model. This approach starts with the assumption that the problem is with the application and not the network infrastructure.

Divide-and-Conquer - The divide-and-conquer approach is generally used by more experienced network technicians. The technician makes an educated guess targeting the problem layer and then based on the observed results, moves up or down the OSI layers.

Using the OSI model as a guide, the help desk technician can query the customer to help define the problem and isolate the cause.

Often the script takes a bottom-up approach to troubleshooting. This is because physical problems are usually the simplest to diagnose and repair, and the bottom-up approach starts with the Physical Layer.

Layer 1 Troubleshooting

The technician starts with Layer 1 issues first. Remember, Layer 1 deals with the physical connectivity of the network devices. Layer 1 problems often involve cabling and electricity, and are the reasons for many help desk calls. Some of the more common Layer 1 problems include:

Device power turned off

Device power unplugged

Loose network cable connection

Incorrect cable type

Faulty network cable

Faulty wireless access point

Incorrect wireless settings, such as the SSID

To troubleshoot at Layer 1, first check that all devices have the proper electrical supply, and that the devices are turned on. If there are any LEDs that display the status of the connectivity, verify with the customer that they are indicating correctly. If on-site, visually inspect all network cabling and reconnect cables to ensure a proper connection.

When remotely troubleshooting a problem, the technician should advise the caller through each step, what to look for, and what to do if an error is found. If it is determined that all Layer 1 issues have been addressed, it is time to travel up the OSI model to Layer 2.

Layer 2 Troubleshooting

Network switches and host NICs perform Layer 2 functions. Layer 2 problems can be caused by faulty equipment, incorrect device drivers, or an improperly configured switch. An on-site technician can check whether the NIC is installed and working properly. Reseating the NIC, or replacing a suspected faulty NIC with a known good NIC, helps to isolate the problem. The same process can be done with any network switch.

            Layer 3 Troubleshooting

At Layer 3, the technician needs to investigate the logical addressing used in the network, such as the

P address within the assigned network

Correct subnet mask

Correct default gateway

Other settings as required, such as DHCP or DNS

At Layer 3, several utilities can assist with the troubleshooting process. Three of the most common command line tools are:

ipconfig - Shows IP settings on the computer

ping - Tests basic network connectivity

tracert - Determines if the routing path between the source and destination is available

           Layer 4 Troubleshooting

it is time to check the higher layers. For example, if a network firewall is used along the path, it is important to check that the application TCP or UDP port is open and no filter lists are blocking traffic to that port.

           Layers 5 through 7 Troubleshooting

Most network problems can usually be resolved using these Layer 1, 2, and 3 troubleshooting techniques.

The technician should also check the application configuration. For example, if troubleshooting an email issue, ensure that the application is configured with the correct sending and receiving email server information. It is also necessary to ensure that domain name resolution is functioning as expected.

For remote technicians, higher layer issues can be checked by using other network utility tools, such as a packet sniffer, to view traffic as it crosses the network. A network application, such as Telnet, can also be used to view configurations.

2.3.1 Help Desk Troubleshooting Scenarios

The number and types of calls received by the help desk can vary extensively. Some of the most common calls include problems with email, host configuration, and connectivity.

Email Issues

Can receive but not send

Can send but not receive

Cannot send or receive

Nobody can reply to messages

A common cause of many email problems is using the wrong POP, IMAP, or SMTP server names. It is best to check with the email administrator to confirm the proper name of the POP or IMAP server and SMTP server. In some cases, the same server name for both POP/IMAP and SMTP are used.

When troubleshooting these issues over the phone, it is important to step the customer through the configuration parameters carefully.

Host Configuration Issues

A common issue that can prevent connectivity to the Internet or other network resources is improperly configured host addressing information. In environments where the IP addressing information is manually configured, it is possible that the IP configuration was simply entered incorrectly.

In environments where hosts are configured to dynamically receive an IP address from an assignment server, such as a DHCP server, the server may fail or become unreachable due to network issues.Once the link-local process selects an IP address, it sends an ARP query with that IP onto the network to see if any other devices are using that address.

If there is no response, the IP address is assigned to the device, otherwise another IP address is selected, and the ARP query is repeated. Microsoft refers to link-local addresses as Automatic Private IP Addressing (APIPA).When troubleshooting both manually and dynamically configured hosts, use the host command ipconfig /all to verify that the host is using the appropriate IP configuration.

Customer Connectivity Issues

First-time customers may have problems with installing the hardware as well as software configuration settings. Existing customers notice connectivity problems when they cannot open a web page or connect to instant messaging or email.

There are many reasons why a customer has no connectivity, including the following:

Delinquent payments for services

Hardware failures

Physical layer failures

Incorrect application settings

Missing application plug-ins

Missing applications

Other problems, such as software issues, may be more difficult to detect. One example is an incorrectly loaded TCP/IP stack, preventing IP from operating correctly. The TCP/IP stack can be tested and verified using a loopback address. The loopback is a special address, the reserved IPv4 address 127.0.0.1, which hosts use to direct traffic to themselves. The loopback address creates a shortcut method for TCP/IP applications and services that run on the same device to communicate.

You can ping the loopback address to test the configuration of TCP/IP on the local host. If you are unable to get a response when pinging the loopback address, suspect an improperly configured or installed TCP/IP stack.

Addresses 127.0.0.0 through 127.255.255.255 are reserved for testing purposes. Any address within this block will loop back within the local host. No address within this block should ever appear on any network. Despite the fact that the entire 127.0.0.0/8 network range is reserved, the only address typically used for loopback testing is the 127.0.0.1 address.

2.3.2 Creating n Using  Help Desk Records

When a Level 1 help desk technician receives a call, there is a process followed to gather information. There are also specific systems for storing and retrieving relevant information.

extremely important to gather the information. The information gathering and recording process starts as soon as the technician answers the phone. When the customer identifies who they are, the technician accesses the relevant customer information.When a problem is resolved, the solution is documented in the customer work order or trouble ticket, and in a knowledge-base document for future reference.

 Occasionally, the Level 1help desk technician may receive a call that cannot be resolved quickly. In this instance, the technician is responsible for passing the call to a Level 2 technician who is more qualified to resolve the issue. Both Level 1 and Level 2 help desk technicians attempt to solve customer problems using the telephone, web tools, and possibly remote desktop sharing applications

if the help desk technicians are not able to fix the problem remotely, it is often necessary to send a Level 3 on-site technician to the customer premise location.

to correctly solve the problem, technicians at the place a trouble ticket to see what was previously done. This review gives engineers some background information and a logical starting point.

although there are instances where the technician is unable to make the needed repairs and must bring the damaged equipment back to the ISP site for additional troubleshooting.

2.3.3 Customer Site Precedures

There are four steps an on-site technician performs before beginning any troubleshooting or repair at the customer site:

Step 1. Provide proper identification to the customer.

Step 2. Review the trouble ticket or work order with the customer to verify that the information is correct.

Step 3. Communicate the current status of any identified problems and the actions the technician expects to take at the customer site that day.

Step 4. Obtain permission from the customer to begin the work.

Once the technician is familiar with all issues, the work can begin. The technician is responsible for checking all device and network settings, and running any necessary utilities. The technician may also have to swap out suspected faulty hardware with known good hardware to determine if a hardware problem exists.
installing new or replacing existing equipment, it is important to minimize the risk of injury by following good safety practices. Many employers offer safety training as part of their employee services.

Ladders

Use ladders to reach high locations to install networking cable and to install or troubleshoot wireless access points in places that are difficult to reach.

High or Dangerous Locations

Sometimes network equipment and cables are located in high and dangerous places, such as on the side of a building, on roof tops, or in an internal structure such as an elevator shaft, that is not accessible by a ladder. Using a safety harness reduces the risk of falling.

Electrical Equipment

If there is a risk of damaging or coming in contact with any electrical lines when handling hardware, consult with the electrician of the customer about measures that can be taken to reduce the risk of electrical shock.

Awkward Spaces

Network equipment is often located in narrow and awkward spaces. Ensure that the work area is properly lighted and ventilated. Determine the best way to lift, install, and remove equipment to minimize the risks.

Heavy Equipment

Networking devices can be large and heavy. Plan to have the correct equipment and trained personnel when heavy equipment needs to be installed or moved at a customer site.

After the technician makes any configuration changes or installs new equipment, the technician must observe the results to ensure proper operation. When finished, the technician communicates the nature of the identified problem to the customer, what solution was applied, and any follow-up procedures. Before the problem can be considered fully resolved, the technician must obtain the acceptance of the customer. The technician can then close the trouble ticket and document the solution. A copy of the documentation is left with the customer. The document includes the original help desk call problem and the actions taken to solve the problem.

For future reference, the technician also records the problem and the solution in the help desk documentation and FAQs.

In some cases, a technician on-site to uncover problems that require network upgrades or reconfiguration of network devices. When this happens, it may be outside the scope of the original ticket disorders. These issues are usually communicated to both the customer and the ISP network personnel for further action.

2.4.1 Summary

 + help desk technician provide solution to customers network problem

 + Use support usually exists at three levels : T1, T2 and T3

 + Incident management is the basic procedure followed when a help desk technical initiates the standarsproblem solving processes

 + Hep Desk Operation relies on opening trouble tickets and logging information.

+ Customer service and  interpersonal skills are important when handling difficult clients and incidents

+ Skills required by Help Desk technicians for successful communication include :

a .   Preparation

b .   Courteous greeting

c .    Listening to the customer

d .   Adapting to costumer temperament

e.    Correctly diagnosing a simple problem

f .    Logging the call

                + A layered approach is used for troubleshooting

+ The OSI Model Breaks The task of network communications down into multiple processes. Each Process is a small part of the larger task.

+ The Seven Of the OSI layer reference model can be divided into two catagories : Upper and Lower layers

+ Upper layers consist of any layer above the transport layer and are implementend 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-Bottom, or divide-and-conquer approaches

+ Some of the most common customer service calls are about email and connectivity issues.

+ Information gathered form the customer is transferred to the trouble ticket

+ Level1 and level 2 help desk technician attempt to slove customer problems over the telephone, web or remote desktop sharing applications.

+ sometimes it is necessary to dispatch a level 3 on-site technician

+ It is important to document the solution on the costumer work order, the trouble ticket and in a knowledge-base document for future reference