*Cisco Notes 1/23/06 - Hot Keys (Ctrl+F) - Command Prompt - Network Configuration - Selection of NIC - Abbreviations - Terminology - OSI models - UTP Cable Pin Outs - Notes * = Important for upcoming test *** = Very Important for upcoming test Command Prompt (Run:// CMD) ipconfig_ Shows IP ipconfig/all_ Shows server address and computer stats ping"ip"_ Checks connectivity, sends out 4 packets 127.0.0.1_ (loopback) tests if connected to server Network Configuration TCP/Setting Configure_ Go to Control Panel 1-------3 2-------6 3-------1 4-------4 5-------5 6-------2 7-------7 8-------8 Straight Through 1-------1 2-------2 3-------3 4-------4 5-------5 6-------6 7-------7 8-------8 Roll Over 1-------8 2-------7 3-------6 4-------5 5-------4 6-------3 7-------2 8-------1 Cross Connect (Used to connect two switches) 1-------3 2-------6 3-------1 4-------7 5-------8 6-------2 7-------5 8-------4 Hubs -Types of Hubs - Passive hubs serves as a physical connection point only. It does not boost or clean the signal and does not need electrical power. - Active hub needs power to repeat the signal before passing it out the other ports - Intelligent or smart hubs are active hubs with a microproccesor chip and diagnostic cpabilites - also called concentrator or multiport repeater - Devices attached toa hub recieve all traffic traveling through the hub - The more devices there are attached to the hub, the more likely there will be collisions - A collision occurs when two or more workstations send data over the network wire at the same time - All data is corrupted when that occurs - Every device connected to the same network segment is said to be a member of a collision domain Outline of model 5 1. a network interface card (NIC) provides network communication capabilities to and froma PC. 2. Use a crossover cable to connect between two similar devices, such as switches, routers, PCs, and hubs 3. Use a straight throught cable to connect between different devices such as connections between a switch and a router, a switch and a PC, or a hub and a router. 4. There are two major types of LANs, peer to peer and client/server 5. WANs use a serial data transmission. WAN connection types include ISDN, DSL, and cable modems. 6. A router is usually the DTE and needs a serial cable to connect to a DCE device like a CSU/DSu 7. The ISDN BRI has two types of interfaces, S/T and U interfaces. To interconnect the ISDN BRI port to the service-provider device, a UTP category 5 straight throught cable with RJ-45 connectors, is udes. 8. A phone cable and an RJ-11 connector are used to connect a router for DSl service. 9. Coaxial Cable and a BNC connector are used to connect a router for a cable service 10. Rollover cable is used to connect a terminal and the console port of and inter networking device. Interconnecting Devices - Use Straight-Through cables for - Switch to Router - Switch to PC or Server - Hub to PC or Server - Use Roll-Over cables to (Rollover Cable=Console Cable) - Connect a terminal to a console port - Use Crossover cables for - Switch to Switch - Switch to Hub - Hub to Hub - Router to Router - PC to PC - Router to PC Notes - A modem (csu/dsu) or Modular Demodulator provides computer with telephone, converts data from digital to analog - Benefits Of OSI_ - Reduces Complexity - Standardizes interfaces - Facilitates modular engineering - Ensures inter operable technology - Accelerates evolution - Simplifies teaching and learning - A bridge connects 2 LANs - To connect PC to a router to configure use console cable (Rollover cable) -DB-9 connects to router -Two ways for wireless to connect 1.Authentication 2.Association - Three ways voltage is created 1.Friction 2.Magnetism 3.Solar - Three imporant number systems - Base 2 (binary) - Base 10 (decimal) - Base 16 (hexi decimal) - The ten primary test parameters that must be verified for a cable link to meet TIA/EIA-568-B standards are 1. Wire Map 2. Insertion Loss 3. Near-End Crosstalk (NEXT) 4. Power sum near end crosstalk (PSNEXT) 5. Equal-Level Far End Cross Talk (ELFEXT) 6. Power sum equal-level far end crosstalk (PSELEXT) 7. Return LOss 8. Propagation Delay 9. Cable Length 10. Delay Skew - Two ways of considering bandwith in communications systems are analog and digital - Analog bandwidth describes the range of frequencies transmitted (hertz; Hz) - Digital bandwidth measures how much information can flow from one place to another in a given amount of time (BPS) - 6 things to distort a bit 1. Propogation 2. Attenuation 3. Reflection 4. Noise 5. Timing Problems - Timing Problems - Dispersion - Jitter - Latency - TIA/EIA-568-B Standard - The ten cable test 1. Wire Map 2. Insertion Loss 3. Near-end Crosstalk (NEXT) 4. Power sum near end crosstalk (PSNEXT) 5. Equal level far-end crosstalk (ELFEXT) 6. Power sum equal-level far end crosstalk (PSELFEXT) 7. Return loss 8. Propogation delay 9. Cable length 10.Delay skew - Companies worked together to create and implement ethernet - Digital - Intel - Xerox - Three extended standards for ethernet - 802.3u for fast ethernet - 802.3z foe Gigabit Ethernet over fiber - 802.3ab for gigabit ethernet over utp - Use straight through cables for - Switch to router - Switch PC or server - HUb to PC or server - Use rollover cables to - Connect a terminal to a console port - Use Crossover cables for - Switch to Switch - Switch to hub - hub to hub - router to router - pc to pc - No more then four repeaters can be used on a LAN. This rule is used to limit latency added to frame travel by each repeater thus reducing late collisions. - Cat 5 cables good 100 meters - Framing is the Layer 2 encapsulation process. A frame is the layer 2 protocol data unitit (PDU) - There are three primary ways to calculate the FCS number: Cyclic redundancy check (CRC) Two-dimensional parity Internet checksum - Why people choose ethernet Simplicity and ease of maintenace ability to incorporate new technoilogies reliability low cost of installation and upgrade bandwith can be increased without changing under lying technology - IEEE 802 Committees -802.3 Logical link control (LLC) -802.3 CSMCA/CD Working Group - IEEE 802.3 - 10 MBIT - IEEE 802.3U - 100MBIT - IEEE 802.3Z MBIT -801.11 Wireless LAN (WLAN) -802.5 Token Ring -802.14 cable tv - BASE band signaling is 10 BROAD band is 100 or higher - Token ring is one of the deterministic protocols where collisons do not occur - jabber is an extremely long bad frame - IP addresses are assigned to hosts in the following ways: Statically – manually, by a network administrator Dynamically – automatically, using reverse address resolution protocol, bootstrap protocol (BOOTP), or Dynamic Host Configuration Protocol (DHCP) Illegal Frames 46 byte frame- short frame 64 byte frame- under long frame is loanger than legal limit giant a frame that is to long is called this on a router Layer 2 protocol data unit - The names of the fields are as follows: Start Frame field Address field Length/Type field Data field Frame Check Sequence (FCS) field STP Blocking- Recieves BPDU's only Listening- building "active" topology Learning- building bridging table Forwarding- sending and receiving user data Disabled- administratively down Five Address classes Class A-for very large networks Class B-for medium networks Class C-For Small Networks Class D-For multicast groups; no need for network and host parts 11/02/05 Test Q.A company needs to extend the LAN to six seperate building. To limit the amount of signal attenuation on the LAN media, what type of media would be the best to use between the building A.Fiber Q.A small company is having difficulties on its LAN. After Performing some tests, a technician has determined that the copper media supporting the LAN experiencing abnormal attenuation. What are two possible causes of the problem? A. 1.Deffective connectors, 2.execivley long cables Q.What is the cause of crosstalk in UTP cable? A. Cable pairs that are untwisted because of poor termination of the cable Q.Which of the following describes frequency? A. Number of cycles each second Q. HOw are binary ones and zeros represented in fiber optic cable installations A. 1. Light/No LIght 2. Increasing/ Decreasing LIght Q. What factors need to be considered to limit the amount of signal attenuation in ethernet cable runs? A. 1. Length of cable 2. Installation of connection on the cable Q. Which of the following are detected by the wire map test A. 1. Opens 2. Reversed-pair faults 3. Short circuits Q. To ensure reliable LAN communications, what should a technician be looking for when attaching connectors to the ends of UTP A. That the wire pairs remain twisted as much as possible Q. What conditions are described when transmission signals from one wire pair affects another wire pair? A. 1. noise 2. cross talk Q. What is expected when crosstalk is present in networks with higher transmission frequencies? A 1. Increase in crosstalk 2. destruction of more of the data signal 11/17/05 Test -two or more nodes transmitting at the same time is a collision. - Switch regulates bandwidth, they combine the connectivity of a hub with the traffic regulation of a bridge - serial provides physical connectivity for a WAN - serial 1/0 is the correct syntax for modular port in router - RJ-45 connectors - 10 base T - 100 base TX - 1000 base T -Router Functions - Broad cast containmnent - segmenting the network - switch and bridge layer 2, router layer 3, hubs transceiver repeater layer 1 Test Questions/Answers Q. What device is used to connect hosts to an Ethernet Lan and requires a straight through UTP cable between the hosts and this device? A. Switch Q. Users with system that are attached to a Hub are complaining about poor response time. What device could replace the hub and provide immediate response time improvement? A. Switch Q. At which layer of the OSI model does the MAC address of a NIC reside? A. Data Link Q. Which statement describes a typical use of Gigabit Ethernet? A. To provide high-speed connectivity for backbones and crossconnects Q. What is the most common type of cabling used in LANs A. UTP Q. In which situation would a crossover be used to connect devices in a network A. Switch to Switch, Switch to Hub Q. LAyer 1 devices A. HUb, Repeater Q. responcibility of DCE A. clocking for the synchronous link Q. what is the charecteristic of the operation of a hub A. forwards a from out all interfaces except inbound interface Q. benefits of peer to peer A. easy to create, no centeralized equipment required, centralized adminastrator not required Q. Which addresses does a bridge use to make filtering and switching decisions A. destination MAC 12.4.05 what happens to frame accross a segment frame format remains the same. how many hexadecimal in a mac address 12 function of nic in a pc a nic connects the Pc to the network media a NIC detects collision on the ethernet segment a nic passes contents of selected frames to the upper osi layer mac layer is 2 which interfaces have a mac address ethernet and token ring how does the nic know when it can transmit data after listening for an abesnce of a signal on media what charecterisics describe CSMA/CD non deterministic, collision envoirment, first come firts serve Which two devices can provide full duplex nic, layer 2 switch On a LAN one workstation can sendn data on the line while it is revieving data, what type if data transfer does this describe full duplex four computers connected to a hub, which configuration would cause collision and era network administratively configured full duplex the switch and workstation are configured full duplex, which statement reflects the operation of this link? no collison will occur on this link Host 1 and host 4 both transmit data at the same time, how do the host respond on a network at the end of jame signal hosts 1,2,3,4 invoke a backoff algorithm If host has data to transmit after the backoff period of that host the host checks to determine if the line is idle before transmitting whena a collision occurs in a network using csma/cd how do hosts with data transmit respond after the backoff period has expired the hosts return to a listen-before-transmit mode which statement describes CSMA/CD on an Ethernet segment manages the retransmission of frames after a collision occurs devices when the collsion occurs do not have priority for re transmission a technician wants to increase the availble bandwith for the workstation by allowing the switch and the NIC on the work station full duplex Why do hosts on the ethernet segment use random delay before attempting to transmit a frame a random delay helps prevent the stations from expierencing another collsion during the transmission layer of osi model does ethernet function data link, physical which of the following are specified by IEEE standards as sublayers of OSI data link layer MAC, llc Where does the mac address originate burned into rom/ nic card 12.18.05 10 base2, 10 base5, and 10base-T are three ethernet technologies that are considered "legacy" because they are old and must be supported by technicians Category 3 UTP, Category 5 UTP and Category 5e UTP can be used in a 10 base-t network The maximum distance for 10 base-t is 100 meters before the signal will degrade When using 100 base-t Category 5 UTP cable, RJ-45 pins: 1-2, and 3-6 are used to transmit(TX) and recieve(RX) data 1000 base-t can transmit gigabit speeds which will require all 8 wires, or 4 pair to TX and RX (Transmit and Recieve) at the same time Layer 1 of the OSI medel deals with various Ethernet technologies The 5-4-3 rule allows for 5 sections of cable 4 devices, such as repeaters, and 3 devices, such as computers, attached to those sections 100 Base-TX and 100 Base-FX are considered fast Ethernet technologies. They use fiber technology Gigabit Technology are usually used as backbone cabling and workstations as an options IEEE 802.3 recommends 1000 base-LX for all backbone installations 1/05/06 bridges make deciscions based on MAC addresses. or layer 2 addresses bridges create collisions domains, which reduce traffic, but do not affect logical, or layer 3 addresses The entire network will be part of the same broadcast domain Each port on a switch os om ots own collision domain, A 20 port switch will have 20 collision domains increasing the number of collision domains is known as micro-segmantation A switch builds and maintains a COntent adressable MEmory (CAM) table, which holds the mac information for each port Most memory devices store and retrieve data by addressing specific memory locations In cam stored data, items can be identified by the content rather than by its address A switch is a layer 2 device that uses a destination mac address to determine where a frame is sent A hub shares bandwidth and a switch will provide more throughtput that a hub. theoretically there are no collisions in a switched envoirment A technician who is managing a network which is using hubs finds that it is slow. If he changes all the hubs over to switches he will increase LAN network performance A switch not a hub has the ability to function on full or half duplex mode in a LAN envorment A uni cast packet is sent and contained within a switched envoirment A switch is a device that will allow dedicated bandwidth to divices aon a network Bridges and switches use MAC addressed to make forwarding decisions The main devices that re time and regenerate signals along an extended media are: hubs and repeaters Multiple collsion domains are created using switches bridges and routers FFFF.FFFF.FFFF in hexadecimal is a broadcast signal. 255 would be the deciamal and 11111111 would be the binary equilvant A router is the device used to control broadcast traffic. Whether too much or too little traffic A bridge that does not recognize a mac address within its table will send the frame to all other connected ports except its own to find a destination The only device that will reduce the size of the collison and broadcast domains in a lan envoirment is the router Spanning tree protocol is used to prevent switching loops on a lan envoirment. redundant paths are cancelled out Layer 2 bridges. As more nodes are added to an Ethernet segment, use of the media increases. Ethernet is a shared media, which means only one node can transmit data at a time. The addition of more nodes increases the demands on the available bandwidth and places additional loads on the media. This also increases the probability of collisions, which results in more retransmissions. A solution to the problem is to break the large segment into parts and separate it into isolated collision domains. To accomplish this a bridge keeps a table of MAC addresses and the associated ports. The bridge then forwards or discards frames based on the table entries. The following steps illustrate the operation of a bridgeTo accomplish this a bridge keeps a table of MAC addresses and the associated ports. The bridge then forwards or discards frames based on the table entries. Layer 2 switches. Generally, a bridge has only two ports and divides a collision domain into two parts. All decisions made by a bridge are based on MAC or Layer 2 addresses and do not affect the logical or Layer 3 addresses. A bridge will divide a collision domain but has no effect on a logical or broadcast domain. If a network does not have a device that works with Layer 3 addresses, such as a router, the entire network will share the same logical broadcast address space. A bridge will create more collision domains but will not add broadcast domains. A switch is essentially a fast, multi-port bridge that can contain dozens of ports. Each port creates its own collision domain. In a network of 20 nodes, 20 collision domains exist if each node is plugged into its own switch port. If an uplink port is included, one switch creates 21 single-node collision domains. A switch dynamically builds and maintains a content-addressable memory (CAM) table, which holds all of the necessary MAC information for each port. Each port on a switch that uses STP exists in one of the following five states Blocking Listening Learning Forwarding Disabled A port moves through these five states as follows From initialization to blocking From blocking to listening or to disabled From listening to learning or to disabled From learning to forwarding or to disabled From forwarding to disabled Here are some examples of shared media and directly connected networks Shared media environment – This occurs when multiple hosts have access to the same medium. For example, if several PCs are attached to the same physical wire or optical fiber, they all share the same media environment. Extended shared media environment – This is a special type of shared media environment in which networking devices can extend the environment so that it can accommodate multiple access or longer cable distances. Point-to-point network environment – This is widely used in dialup network connections and is most common for home users. It is a shared network environment in which one device is connected to only one other device. An example is a PC that is connected to an Internet service provider through a modem and a phone line. The types of devices that interconnect the media segments define collision domains. These devices have been classified as OSI Layer 1, 2 or 3 devices. Layer 2 and Layer 3 devices break up collision domains. This process is also known as segmentation. The four repeater rule in Ethernet states that no more than four repeaters or repeating hubs can be between any two computers on the network. The 5-4-3-2-1 rule requires that the following guidelines should not be exceeded: Five segments of network media Four repeaters or hubs Three host segments of the network Two link sections with no hosts One large collision domain Layer 2 devices segment or divide collision domains.They use the MAC address assigned to every Ethernet device to control frame propagation. Layer 2 devices are bridges and switches. 1/10/06 TEST Q1.What is charecteristic of the operation of a layer 2 switch? A.4. Uses the destination MAC address to determine the specific interface to forward a frame Q2.Two newly hired technicians are disussing the implementation of a new LAN. One Technician proposese installing a hub. the Other technician advises installing a switch. Which statement are true about the diffrences between hubs and switch. A.4-5. A switch provides more thouroughput to hosts on a LAN, A switch provides a collision free envoirment Q3. 48 connections Slow access, replaces 10mbs hub with 100mbs problem still exists A.1.Replacce hub with switch Q4. A.4 Q5. A.1 Q6. An administrator would like to connect a workstation on a 192.168.0/24 network. The device selected by the administrator must allow connectivity without sharing bandwidth/ Which device would be appropriate? A.3.Switch Q.7. devices uses the MAC address for forwarding deciscions? A.2-4 Q.8 A.2-5.repeater and hub, regenerate data signals Q.9 A.3-4. switch and router create multiple collision domains Q.10 A.1. 1 broadcast domain per network Q.11 A.2. FFFF.FFFF.FFFF. is broadcast signal Q.12 A.3. router controls broadcast traffic Q.13. A.4. Q.14 A.3. Q.4. 1/23/06 -One Class A, a range of Class B addresses, and a range of Class C addresses are not routed on the Internet -10.0.0.0- 10.255.255.255 -172.16.0.0- 172.31.255.255 -192.168.0.0- 192.168.255.255 -A Router uses Network Address Translation (NAT) to translate private addresses to public addresses. -Subnetting a network means to use the subnet mask to divide up a network into a smaller, segments or subnets -Subnetting has prevented the wasting of usable host addresses -To create a subnet address, some bits from the host field are borrowed, and designated as subnet bits -Ip addresses can be assigned statically or dynamically -Static addressing is manually done by a system administrator -Best on small, infrequently changing networks -Good record-keeping is essential -servers, printers and routers should be given static addresses -static addressing is NOT scalable - Reverse Address Resolution Protocol (RARP) associates a known MAC address with an IP addesses -IP source addresses are needed for the address field in all ip packets -RARP used in diskless workstations -A RARP server must be present -RARP requests are broadcast onto the LAN and are responded to by the RARP server, usually a router -RARP_Know MAC looking for IP -ARP_Knows IP looking for mac _Review The Transport layer defines end to end connectivity between host applications In TCP/IP, the IP part does not provide acknowledgement of the data that is delivered IPv4 class C will provide the greatest number of networks IPv4 class A will provide the greatest number of hosts 127.0.0.1 is considered a "loopback" or ping address. Technically is considered a class A address. Private addresses were developed because there was a lack of public ip addresses Public IP addresses mumst be unique over the entire network private addresses are 10.0.0.0-10.255.255.255 172.16.0.0-172.31.255.255 192.168.0.0-192.168.255.255 servers usually are manually cinfugure with ip addresses when you use the :obtain an ip address automatically" on youre desktop computer here in class you are using the DHCP DHCP will dynamically assign addresse thus saving administrator work loads REMEMBER!!! ARP KNOWS AN IP ADDRESS AND IS LOOKING FOR A MAC ADDRESS