CCNA advanced network technical materials

CCNA advanced network technical materials Network Basics Encapsulation: attaches necessary protocol information to the data before network transmission. Unencapsulate: unseal data from a specific protocol header. Peer layer communication: each layer of the source sender's OSI model must communicate with the peer layer of the target. OSI reference model: 1 physical layer: defines electrical, mechanical, and procedural functions and standards for physical links between systems. (BIT) 2 data link layer: provides reliable data transmission on physical links. (FRAME) 3 network layer: Provides the connection and path selection between the two hosts. (Group) 4 transmission layer: segments the data to be sent on the sending host, and reassembles the data segment to the data stream on the receiving host system. (Segment) 5 Session Layer: establishes, manages, and terminates sessions between two hosts. 6. Presentation Layer: ensure that the information sent by the application layer of one system can be read by the application layer of another system. 7 Application Layer: Provides network services for your applications. TCP/IP model: Application Layer: corresponding to OSI application layer, presentation layer, and Session Layer transport layer: corresponding to OSI transport layer INTERNET layer: corresponding to OSI network access layer: corresponding to OSI data link layer and Physical Layer Ethernet Basics A Media Access Control (MAC) protocol is a protocol used to determine which computer in a shared media environment permits data transmission. There are two types: deterministic MAC protocol and non-deterministic MAC protocol. certainty: take turns, such as the starting ring, FDDI non-deterministic: service first, for example, CSMA, cd csma, and CD carriers listen to multiple channels for access/conflict detection. Features: Listen first, send 1 while listening, and listen first. If the media is idle, send. 2. If the media is busy, continue listening. If the media is idle, send it immediately. 3. If a conflict occurs, wait for a random distribution and repeat Step 1. Ethernet Switching Technology Bridging: the technology used by the bridge to connect two or more LAN segments. Working Principles: flooding, learning, forwarding, and filtering. If the source LAN is the same as the target LAN, the frame is discarded. (Filtering) if the source LAN is different from the target LAN, the frame is forwarded. (Learning, forwarding) If the destination LAN is not sure, the frame is broadcast. (Flooding) Switching: the process of receiving recent data frames from one interface and sending them through another interface. Essence: multi-port bridges. Differential segment: a LAN is a CIDR Block separated by a vswitch, which generates a non-conflict domain in a large conflicting domain. Exchange mode: storage and forwarding throughout the exchange without sharding exchange TCP/IP Protocol TCP/IP protocol set Application Layer: File Transfer: FTP, TFTP, NFS Email: SMTP remote Logon: TELNET, RLOGIN Network Management: SNMP name management: DNS Transport Layer: transmission Control Protocol TCP, User Datagram Protocol UDPINTERNET layer: Internet Protocol IP, Internet Control Packet protocol ICMP, address resolution ARP, reverse Address Resolution rarp mac addressing compared with IP addressing 1 the applicable network range is different. MAC is only applicable to small networks, while IP is applicable to large heterogeneous networks. 2. The address structure is different. MAC is a plane address, while IP is a hierarchical address, and the address itself carries location information. 3. the layers of the OSI model are different. MAC is at the data link layer while IP is at the network layer. 4. The number of addresses is different. The IP address has a certain amount, while the MAC address is almost unlimited. 5. The address format is different. MAC is 48 bits and IP is 32 bits. Reserved address space broadcast address, loopback address, private address, network address, Class D and Class E address subnet planning: for more effective communication, divide a large network. (Subnet Planning) ip address acquisition method: static retrieval: dynamic retrieval: rarp bootp dhcp Default Gateway: IP address of the router interface connected to the source device's network segment. Gateway's responsibility: when the source device requires a different destination address than itself in a network, if the source device does not know the destination MAC address, it must rely on the gateway to achieve its data. Validation technology is a technology that ensures reliable transmission of data streams, including two aspects: 1. the receiving end sends a validation message to the source end. 2. the sender starts the timer when sending the data segment. If no confirmation message is received within the specified time range, the sender resends the data. Confirm with confirmation-you can further reduce the confirmation frame. Window Technology: an end-to-end information control method. Number of Windows: the number of packets that the sender can send before receiving the receiver's confirmation signal. Slider window: it is the combination of validation technology and window technology. During the session process, TCP can dynamically modify the window size through negotiation. The window size is controlled by the receiving end. Port: used to track different sessions over the network at the same time. Main functions of the transport layer: Segment and reorganize byte streams. 2. Ensure Reliable data transmission and traffic control. 3. Establish an end-to-end connection. 4. Send data segments from one host to the other. 5. Ensure that the entire packet is in the correct process on the target host. Comparison Between TCP and UDP 1 TCP is a reliable connection-oriented transmission method, while UDP is an unreliable transmission method. 2. TCP can only be one-to-one transmission, while UDP can be one-to-multiple transmission. 3. TCP ensures data correctness and has high requirements on computer network resources. UDP does not guarantee data correctness and has low requirements on computer network resources. Routing selection Basics The main function of the network layer is to send the group to the destination through the selected path from the source machine. Comparison between the virtual circuit subnet and the datagram subnet: 1. Establish a connection after the virtual circuit subnet is selected, and the Group has a virtual circuit number without the destination address. Each group has a destination address, and the path selection is flexible. 2. After the destination is reached, virtual groups do not need to be re-ordered; data groups need to be re-sorted. 3. virtual hosts have less workload, and error check and traffic control are transparent to users. Data Error Control and traffic control are completed by high-level protocols. 4. virtual communication costs are high, low cost. Route Protocol: IP protocol routing protocol: static route: Dynamic Route: Distance Vector Route Selection protocol (RIP) RIP uses the number of hops as the measurement of route selection. When the number of hops reaches the destination network exceeds 15, the packet is discarded. The default period of the RIP route update broadcast is 30 seconds. Link Status routing protocol (OSPF) OSPF Packet type: 1 HELLO 2 database description package 3 link status request 4 link status update 5 link status validation status diagram. Operation steps: 1. Establish a route Adjacent Relationship 2. Elect DR and BDR 3. Discover routes 4. Select the Optimal Route 5. Maintain the route information router. steps: 1. Enable datagram 2. Extract the target network address 3. Select the Optimal Path 4 Based on the route table re-package the datagram 5. Send the datagram out from the corresponding interface the router's function routing selection and forwarding (switching) classless routing: A process of aggregating multiple networks with a bit mask into a single network address. Variable-length subnet mask: (VLSM) an organization uses multiple subnet masks in the same network address space to divide subnets into subnets to improve addressing efficiency. Route summary function: 1 reducing route tables 2 isolating route flip