cisco ccna path

cisco ccna path.Figure Ml shows a MAC address consisting of two parts.48-bit MAC address 24 bits 24 bitsOUI does not network device vendor assignmentFigure 1-11 Format of MAC Addresses1.3.2 Ethernet Devices and How Frames Are Forwarded Up to this point, some basic concepts of Ethernet technology have been introduced, such as the format of frames and MAC addresses. Now, it is time to go over how this technology actually works. Let's start with the most basic cases and then introduce the more complex forwarding behavior of frames and forwarding topology.fM 1. LAN HUBs and Bridges As mentioned earlier, a conflict domain is composed of two or more workstations that need to share the same medium to transmit data. In this way, certain algorithms need to be developed to avoid conflicts arising from multiple devices sending frames simultaneously. Once the conflict occurs, the frames are lost. The conflict problem can be solved with CSMA/CD technology, which supports Ethernet workstations that can detect conflicts and will avoid retransmitting Ethernet frames with other workstations at the same time. The Ethernet bus topology is a simpler example of a conflict domain - all workstations are connected as a bustogether, as shown in Figure 1.12. As can be seen in Figure 1.12, during transmission, the Ethernet signal is weakened by the cable distance for each workstation it passes. Therefore, a LANHUB can be deployed to centrally connect all workstations and build a network with another topology. The purpose of the LAN HUB or repeater is to uniquely regenerate the signal and pass it out of all ports. Such a topology is a typical half-duplex transmission mode, creating a single conflict domain, just like an Ethernet bus topology. Figure 1-13 shows the process by which a message from Host A is regenerated and transmitted outbound through all ports of the HUB.Figure 1.12 Ethernet Bus Topology1.3 Layer 2 Basics and Technologies 21Figure 1-13 Network HUB Regenerative Framing The electronic signal is sent out from all ports to which the device is connected. Before sending a frame, the workstation detects the medium (also called the carrier) to see if any other workstations are also sending frames. If the media is free, the workstation can start sending frames. If two workstations start sending frames almost simultaneously, as shown in Figure 1-14, a conflict will occur. All workstations in the same conflict domain can detect the conflict and will follow the fallback algorithm to delay the sending of frames.