Chapter 11

 Configuring and Testing your Network

            On the previous chapter we plan for our network, we decide to the devices to be use even the cables that are going to connect to the network also we assign the appropriate addresses in each work stations. Now, we are going to configure and test the network. The CISCO IOS or Internetwork Operating System is the system software in CISCO device that is very much useful in the configuration it is used for LAN switches, routers, and other devices.  This provides: basic routing and switching functions, reliable and secure access to networked resources, and network scalability. To access the CLI environment the most common methods are: console, telnet or SSH, AUX port. The console port provides out-of-bound access to a router and it often access the device even when the network services of that device have not been started or have failed. The Telnet and SSH, the Telnet is considered as the method for remotely accessing a CLI session and it requires active networking services on the device. The SSH or Secure Shell is the protocol that is more secure in terms of remote device access and it provides a stronger password authentication through the use of encryption. AUX port or Auxiliary port is almost similar to console port since they have both direct connection to the computer running terminal, but the AUX port can only be useful by the time the console port has problem like unknown parameter.

            A CISCO network device in terms of configuration contains two types: startup configuration file and running configuration file. During the current operation of the device the running configuration is used, when setting a backup of the configuration you had made and loading it as the device started the startup configuration is used. As mentioned that the CISCO IOS is a modal operating system, modal to the point that it contains different modes: user executive mode, privileged executive mode, global configuration mode, and other modes. Each mode has a particular task in the configuration since it determines whether what nodes you are in, during the configuration. The mode that we call as user executive mode is the first mode that prompt before the other, and its argument always ends with greater than “>” like for example router>, that means your privilege as a user is that you can only view the configuration of the router or switch. The privilege mode which is next to the executive mode in the modal structure is the mode that has an argument ends with number sign “#” for example router#, and when you entered the privilege it means that you have all the privilege in changing the configuration of the router or switch, especially if you reach the global configuration mode. When we talks about Global Configuration Mode in your configuration it look like this Router(config)#, and it means that you are on your way to your configuration. There is also what we call as Specific Mode contains: interface mode, line mode, and router mode. Several commands will then follow, for examinations purposes the show command is use and many other commands especially on setting the passwords in each ports, the clock rates, interfaces configuration, renaming the router, banner motd or message of the day and many others. And when the entire configuration had done it is important to save it to the startup configuration or NVRAM for the purpose of backup in case of problem.

            Testing your network after several set ups and configurations is needed to insure that your connections or configurations are correct. The most common commands to determine your network connectivity are the ping and the tracert. The ping command will try to communicate to the target host using its IP address the clear illustrations may look like as follows:

C:\>ping 10.0.0.5

A successful reply would resemble:

Reply from 10.0.0.5: bytes=32 time<1ms TTL=128

Reply from 10.0.0.5: bytes=32 time<1ms TTL=128

Reply from 10.0.0.5: bytes=32 time<1ms TTL=128

Reply from 10.0.0.5: bytes=32 time<1ms TTL=128

Ping statistics for 10.0.0.5:

Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 0ms, Maximum = 0ms, Average = 0ms

     The above ping shows that the certain host is connected to the host that has an IP 10.0.0.5, since there is a reply from it and base from the result there is no packet lost. In tracing a ping or connection the tracert command is useful, the example of it is shown below:

C:\>tracert 192.168.11.1

Tracing route to 192.168.11.1 over a maximum of 30 hops

1 * * * Request timed out.

2 * * * Request timed out.

3 ^C

                The above traceroute result shows the default gateway responds, indicating that there is communication between Host1 and the gateway. On the other hand, the gateway does not appear to be responding to traceroute.

Key terms

1. IOS – known as Internetwork Operating System. This is the Operating System used by the CISCO devices. 

2. Global Configuration Mode- where we can configure global parameters or enter other configuration submodes.

3. Aux port – also known as Auxiliary port, that is used for out-of-bound connectivity with the router.

4. Console port – port that which we can connect a computer with a terminal emulator to the device in order to configure the device. 

5. traceroute – or tracert in the CLI, is a tool or command that shows the path in a real-time from the path to the destination device.

Chapter 10

Planning and Cabling

            In planning and cabling your network you need to consider a need of the devices.  One of the primary devices is the Router it is used to interconnect networks. It has the ability to break up domains. Router can have the LAN and WAN interfaces, it forward packets from one network to another based on network layer information. The switch and hub are the devices to be connected to the network. Hub is the intranet device that regenerates and send signal over all ports, it is chosen as the device within a small LAN and has a single collision domain. The Switch on the other hand is much better than hub since each port of the switch creates a separate collision domain, and it has an enhanced performance and reliability makes it cost effective. There were factors need to be considered in selecting devices for a LAN: Cost, speed and types of ports interfaces, expandability, manageability, and additional features and services. If there is a factor in selecting devices for LAN, there were also factors to be considered in choosing a Router: expandability- having an expansion slots for the purpose of adding new modules, operating system features, and media. Planning a LAN installation, have four physical areas: work area, telecommunications room or distribution facility, backbone cabling or vertical cabling, and distribution cabling or horizontal cabling. When it comes to cabling, recommended length was specified that the maximum distance is limited to 100 meters per channel. Cabling is also is one of the significant factors in signal performance, that’s why Electromagnetic Interference and Radio Frequency Interference are taken consideration when choosing a media type for LAN connection.

            When planning had been done, connecting and cabling are follows. Key points to remember is that when you are connecting the same devices a cross over cable is used, and when you are connecting different types of devices you can use straight through cable. The UTP or unshielded twisted pair has two types of interfaces the MDI or MDIX, the Media Independent Interface (MDI) use the Pin 1 and 2 for transmitting while the pins 3 and 6 are use for receiving, this pins are based on the color combination of the UTP cable. In terms of WAN or wide area connection, on the other hand use Data Communication Equipment (DCE) and Data Terminal Equipment. The DCE mostly is at the WAN access provider end of the link, while the DTE is at the WAN customer or user end of the link. After WAN and LAN are being set up, Network addressing is the next. In addressing we all know that before we can create a subnet we should consider first the number of networks and host to fulfill the requirements. After we determine the number of networks we can now then start subnetting the network, we can now then assign the sunetted IP address to the corresponding hosts base on the usable hosts.

Key Terms 

1.      Router- network layer device that uses one or more metrics to determine the optimal path along which network traffic should be forwarded. Routers forward packets from one network layer information. 

2.      DCE- provides a physical connection to the network, forwards traffic, and provides a clocking signal used to synchronize data transmission between DCE and DTE devices. 

3.      DTE-  the interface between the router and the DCE (CSU/DSU). Controls data coming inbound (WAN to LAN) or outbound (LAN to WAN).

4.      EI/RFI-  is noise induced upon signal wires by ambient radio frequency electromagnetic radiation that causes interference in neighboring wires.

 5.      MDI - Medium dependent interface. It is the pinout order on a NIC card on a PC. On hubs or switches it is also known as an uplink port.

Chapter 9 (Ethernet)

The Ethernet is known as a most frequently used technology nowadays. It functions on the two layers of OSI model the Data Link Layer and Physical Layer. In the data link layer only the lower portion of the data link layer are covered by the Ethernet which Is called Media Access Control Sub layer, it is mainly concerned on the physical components, that is useful for communication and also it had been considered as IEEE 802.3 standard.  The remaining half of the data link layer is called Logical Link Control that which creates a connection with the upper layers and set as IEEE 802.2 standard.

 As Ethernet evolve from its foundation to the point in time, the first version of Ethernet was known as CSMA/CD or Carrier Sense Multiple Access with Collision Detection, it manage and fix the problems encountered whenever plenty of devices communicate and shared physical medium, it detect and handle collisions and manage the communications. The question is, how it is done by the CSMA/CD? There is what we called as process first is called Carrier Sense in which the source devices will listen to the collision on the line before transmitting the message. Second is the Multi-Access it is where the first device sends signal to the second devices, but the signal didn’t reach to the second device and there’s a possibility that the second devices may sends signal too, without reaching each other and the message will eventually destroyed and corrupted. Next process is Collision Detection where the devices can detect an increase of amplitude signal. Jam Signal and random back off is the last process of CSMA/CD, it happens when the collision is detected, the jamming signal is being send to inform other devices that there is a collision happening. After the collision subside the devices that cause collision will not again send message at the same time, so there is what we called as random back off.

MAC address helps in determining the source and destination address within a network, it is 48-bit binary value expressed as 12 hexadecimal digits. It is sometimes called as Burn-in-address since it was encoded to the ROM chip permanently. It is also used to determine whether the message should pass to the upper layers for processing. The MAC address represented depending on the hardware and software manufacturer and it may look like this 00:05:9A:3C:78:00, or 0005.9A3C.7800, which is assigned to workstations. The mapping of IP address to MAC addresses is done through ARP or Address Resolution Protocol. ARP has two basic functions: resolving IPv4 to MAC addresses and maintaining a cache of mappings.  

CISCO (EXPLORATION 1) CHAPTER 8

OSI PHYSICAL LAYER

            The last layer of the OSI model is the Physical layer. It is where the signals are represented as bits in every frame, and also read the data that arrive, into a bit representation and pass it to the Data Link Layer for the purpose of framing the arrived data. The physical layer composed of hardware or electronic circuitry that helps to transmit and read binary representation. _­­­­­This layer functions as the physical components, data encoder, and also performs signaling, when we say encoding task this layer coverts the bits into code that is helpful in identifying the end and the beginning of the frame. In terms of signaling the physical layer will generate signals in wireless or other forms into binary representations 0 and 1, the signal will now then travel to media and it can occupy the media in an amount of time that is called bit time. Signals are characterize as amplitude, frequency, and phrase. The data transfer can be measured also in three ways by bandwidth that which measures the amount of information that can flow to another place in given time, by throughput that enables the measurement of bits transferred across the media in a given amount of time, and by goodput that measure the usable data transferred over a given period of time.

            In order to deliver and send the data to the receiver we need cabling that uses copper wires to control bits between the devices, UTP or Unshielded Twisted Pair was one of the copper media used commonly on Ethernet LAN’s and it minimize the signal degradation due to electronic noise or interface. The fiber optics on the other hand consists of jacket, aramid yarn, buffer, cladding and core. The purpose of cladding is to prevent the light loss from the fiber. Another way of transmitting data is through wireless media which compose of    wi-fi, Bluetooth, WiMax and GSM. Wi-fi is a wireless LAN technology, while Bluetooth is a kind of WPAN or Wireless Personal Area Network that communicate over distances from 1 to 100meters . The Worldwide Interoperability for Microwave Access, while the GSM enable the implementation of GPRS or General Packet Radio Services.