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  • Slide 1
  • ICND -1 Interconnecting Cisco Networking Devices Assembled By David Roberts Knowing what you DONT know is more important than what you DO know. It takes both to have expertise.
  • Slide 2
  • Course Content This course focuses on providing the skills and knowledge necessary to install, operate, and troubleshoot a small branch office Enterprise network, including configuring a switch, a router, and connecting to a WAN and implementing network security. A Student should be able to complete configuration and implementation of a small branch office network under supervision.
  • Slide 3
  • Course Objectives Describe how networks function, identifying major components, function of network components and the Open System Interconnection (OSI) reference model. Using the host-to-host packet delivery process, describe issues related to increasing traffic on an Ethernet LAN and identify switched LAN technology solutions to Ethernet networking issues. Describes the reasons for extending the reach of a LAN and the methods that can be used with a focus on RF wireless access. Describes the reasons for connecting networks with routers and how routed networks transmit data through networks using TCP / IP. Describe the function of Wide Area Networks (WANs), the major devices of WANs, and configure PPP encapsulation, static and dynamic routing, PAT and RIP routing. Use the command-line interface to discover neighbors on the network and managing the routers startup and configuration.
  • Slide 4
  • Course Outline Module 1 - Building a Simple Network Module 2 - Ethernet Local Area Networks Module 3 - Wireless Local Area Networks Module 4 - Exploring the Functions of Routing Module 5 - Wide Area Networks Module 6 - Network Environment Management
  • Slide 5
  • Module 1 - Building a Simple Network Connect 3 PCs together in a Class C, Class B & Class A using IP addresses provided below. Test connectivity with ping. Connect 3 PCs together in a Class C, Class B & Class A using IP addresses provided below. Test connectivity with ping. Class C: PC1: 10.0.0.15 /24 (255.255.255.0) PC2: 10.0.0.16 /24 (255.255.255.0) PC3: 10.0.0.17 /24 (255.255.255.0) Class B: PC1: 10.0.1.15 /16 (255.255.0.0) PC2: 10.0.2.15 /16 (255.255.0.0) PC3: 10.0.100.1 /16 (255.255.0.0) Class A: PC1: 100.200.100.100 /8 (255.0.0.0) PC2: 100.200.200.200 /8 (255.0.0.0) PC3: 100.1.2.3 /8 (255.0.0.)
  • Slide 6
  • Module 1 - Building a Simple Network Part 2 With the Class A IPs still in place, change the subnet to a class B. Use a subnet of /16. (255.255.0.0) With the Class A IPs still in place, change the subnet to a class B. Use a subnet of /16. (255.255.0.0) What happens to the connectivity between the machines? Why? What happens to the connectivity between the machines? Why? What change to the IP address of PC3 can be made in order to restore connectivity between all three PCs? What change to the IP address of PC3 can be made in order to restore connectivity between all three PCs?
  • Slide 7
  • Module 1 - Building a Simple Network Part 3 Reset all PCs to the Class C addressing scheme: Reset all PCs to the Class C addressing scheme: Class C: PC1: 10.0.0.15 /24 (255.255.255.0) PC2: 10.0.0.16 /24 (255.255.255.0) PC3: 10.0.0.17 /24 (255.255.255.0) On PC1 bring up a command line and type in ping t 10.0.0.16 On PC1 bring up a command line and type in ping t 10.0.0.16 On PC2 type in ping t 10.0.0.17 On PC2 type in ping t 10.0.0.17 On PC3 type in ping t 10.0.0.15 On PC3 type in ping t 10.0.0.15 Load up a packet sniffer of your choice on one of the PCs and monitor the NIC. Load up a packet sniffer of your choice on one of the PCs and monitor the NIC. Write down the MAC address for each PC that you see in the sniffer. Write down the MAC address for each PC that you see in the sniffer. What port are the pings coming in & out from? What port are the pings coming in & out from? What protocol are the ping packets being sent over? What protocol are the ping packets being sent over? What is the actual alpha-numeric hex string that the ping packet uses as its data? This can be found in the hex information window. You may have to stop the scanner to isolate one packet. What is the actual alpha-numeric hex string that the ping packet uses as its data? This can be found in the hex information window. You may have to stop the scanner to isolate one packet. Why cant the sniffer see all three PCs? Why cant the sniffer see all three PCs?
  • Slide 8
  • Module 2 - Ethernet Local Area Networks Frames are the format of data packets on the wire. Note that a frame viewed on the actual physical hardware would show start bits, sometimes called the preamble, and the trailing Frame Check Sequence. These are required by all physical hardware and is seen in all four following frame types. They are not displayed by packet sniffing software because these bits are removed by the Ethernet adapter before being passed on to the network protocol stack software.Frame Check Sequencepacket sniffingEthernet adapterprotocol stack
  • Slide 9
  • Module 2 - Ethernet Local Area Networks Part 2 Main procedure of transmission over ethernet: Main procedure of transmission over ethernet: 1. Frame ready for transmission 2. Is medium idle? If not, wait until it becomes ready and wait the interframe gap period (9.6 s in 10 Mbit/s Ethernet). interframe gapsinterframe gaps 3. Start transmitting 4. Does a collision occur? If so, go to collision detected procedure. 5. Reset retransmission counters and end frame transmission 6. Collision detected procedure - Continue transmission until minimum packet time is reached (jam signal) to ensure that all receivers detect the collision 7. Increment retransmission counter 8. Is maximum number of transmission attempts reached? If so, abort transmission. 9. Calculate and wait random backoff period based on number of collisions 10. Re-enter main procedure at stage 1
  • Slide 10
  • Module 2 - Ethernet Local Area Networks Part 3 Dual speed hubs In the early days of Fast Ethernet, Ethernet switches were relatively expensive devices. However, hubs suffered from the problem that if there were any 10BASE-T devices connected then the whole system would have to run at 10 Mbit. Therefore a compromise between a hub and a switch appeared known as a dual speed hub. These devices consisted of an internal two-port switch, dividing the 10BASE-T (10 Mbit) and 100BASE-T (100 Mbit) segments. The device would typically consist of more than two physical ports. When a network device becomes active on any of the physical ports, the device attaches it to either the 10BASE-T segment or the 100BASE-T segment, as appropriate. This prevented the need for an all-or- nothing migration from 10BASE-T to 100BASE-T networks. These devices are often known as dual-speed hubs, since the traffic between devices connected at the same speed is not switched.Fast Ethernet10BASE-Tdual speed hub10BASE-TMbit100BASE-TMbit
  • Slide 11
  • Module 2 - Ethernet Local Area Networks Part 4 More advanced networks More advanced networks Simple switched Ethernet networks, while an improvement over hub based Ethernet, suffer from a number of issues: Simple switched Ethernet networks, while an improvement over hub based Ethernet, suffer from a number of issues: They suffer from single points of failure. If any link fails some devices will be unable to communicate with other devices and if the link that fails is in a central location lots of users can be cut off from the resources they require. They suffer from single points of failure. If any link fails some devices will be unable to communicate with other devices and if the link that fails is in a central location lots of users can be cut off from the resources they require. It is possible to trick switches or hosts into sending data to your machine even if it's not intended for it, as indicated above. It is possible to trick switches or hosts into sending data to your machine even if it's not intended for it, as indicated above. Large amounts of broadcast traffic whether malicious, accidental or simply a side effect of network size can flood slower links and/or systems. Large amounts of broadcast traffic whether malicious, accidental or simply a side effect of network size can flood slower links and/or systems. It is possible for any host to flood the network with broadcast traffic forming a denial of service attack against any hosts that run at the same or lower speed as the attacking device. It is possible for any host to flood the network with broadcast traffic forming a denial of service attack against any hosts that run at the same or lower speed as the attacking device. As the network grows normal broadcast traffic takes up an ever greater amount of bandwidth. As the network grows normal broadcast traffic takes up an ever greater amount of bandwidth. If switches are not multicast aware multicast traffic will end up treated like broadcast traffic due to being directed at a MAC with no associated port. If switches are not multicast aware multicast traffic will end up treated like broadcast traffic due to being directed at a MAC with no associated port.multicast If switches discover more MAC addresses than they can store (either through network size or through an attack) some addresses must inevitably be dropped and traffic to those addresses will be treated the same way as traffic to unknown addresses, that is essentially the same as broadcast traffic (this issue is known as failopen). If switches discover more MAC addresses than they can store (either through network size or through an attack) some addresses must inevitably be dropped and tr

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