OSI and TCP / IP study notes (to be combined with PPT courseware)
Simulator
Role: to build a test environment for testing, verification of theoretical knowledge, to build a real environment validated, convenient and quick.
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PT
- Schools generally use the command incomplete and do not get caught
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GNS3
- NA NP stage can be used, relatively complete command, you can capture analysis, simulation of the exchange is not very good, the route can be simulated.
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EVE
- IE stage can be used, the command line complete, the exchange of good simulation, routing simulation can be.
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ENSP
- HCIA HCIP HCIE exam simulator used to test the use of Huawei, a lot of error, the largest computer resource consumption.
OSI seven-layer model (defined by international standards)
- Application layer
- File, print, messaging, database and application services
- Presentation layer
- Data encryption, compression and conversion services
- Session Layer
- Dialogue control
- Transport Layer
- To-end link
- Network layer
- Routing
- data link layer
- Framing (MAC address)
- Physical Layer
- Physical topology (fiber optic, twisted pair, wireless)
TCP/IP
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5 layers: physical layer, data link layer, network layer, transport layer, application layer
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Layer 4: a network interface layer, network layer, transport layer, application layer
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TCP / IP five
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Application layer PDU data
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The transport layer data segment TCP +
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The network layer packet IP + TCP +
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Data link layer MAC + IP + TCP + data frame
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Physical layer bit bit
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TCP / IP four-layer model to explain in detail
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Physical Layer
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wired
- Twisted Pair (electricity transmission)
- Medium: Copper
- Transmission distance: 100 m
- POE power supply: supply + POE device supports data transmission needs (the need for better wire)
- Unshielded cable: CAT5, CAT5E, CAT6, CAT6E
- Shield lines: CAT6, CAT6E, CAT7
- Optical fiber (optical transmission)
- Media: fiberglass, plastic
- Single-mode transmission distance: 42KM, laser-like
- Multimode transmission distance: 2KM, similar to the flashlight
- Splice expensive machine
- Signals from electromagnetic interference, the transmission rate: 1000M (G), 10000 (TEN-G), 100000 (E)
- RJ45 crystal head
- 568B orange white orange blue green white green white brown white brown from left to right
- 568A green white green orange white blue orange white brown brown white from left to right
- Conceptual cross-line and straight lines (straight line now almost all machine with automatic adaptation)
- Four all-pass core (1236) Fast
- Eight-core all-pass Gigabit
- Twisted Pair (electricity transmission)
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wireless
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2.4G
- Less frequently susceptible to interference, better ability to pass through the wall
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5G
- Higher frequencies, is not susceptible to interference, through the wall poor
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The wireless router RJ45 cable network put out a wireless signal
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802.11A, 802.11B, 802.11G, 802.11N, 802.11AC, 802.11AX corresponds WIFI 1-6
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Wireless AP coverage
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data link layer
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MAC address
- Composed by the hexadecimal
- The first half of the second half of the manufacturer factory random code
- Why should I use MAC address ( switch )
- MAC address out earlier than IP addresses
- MAC address table MAC-> interface forwarding information look-up table, did not send a message to all interfaces (except their own)
- MAC addresses in memory, it may overflow
- Interface bandwidth: E 10 / 100M, F 100M, G 1000M, Ten-G 10000M
- Unit conversion: bit-byte-KB-MB-GB-TB-PB ....
- Double UP: UP physical layer, protocol UP, UP to double data forwarding, forwarding rate auto-negotiation
- Full duplex: a transceiver capable of simultaneously
- Half-duplex: can not send and receive simultaneously (CSMA / CD mechanism concessions)
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MAC Sub-layer: Media Access Control Sub-Layer Media Access Control sublayer
- Specifies how data is transmitted via a physical line, and communicates with the physical layer
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LLC Sub-layer: Logic Link Control Sub-layer logical link control sublayer
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And identifying the type of protocol encapsulated data transmitted over the network
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Sequential transmission of transmission reliability and security control, segmentation and reassembly of data packets, data packets: The main function
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Network layer
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Internet core router route-server.ip.att.net (via telnet have a login account and password above)
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Function: forward packets between different network
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Equipment: routers, three switches
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protocol
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IP
- IPV4
- IPV6
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ICMP
- PING
- Tracert: detected object path, a three-layer device through a Save, TTL response packet is 0, H3C HUAWEI off by default
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ARP
- IP->MAC
- ARP broadcast
- Destination MAC address FF: FF: FF: FF: FF: FF
- The switch receiving the broadcast packets - flooding - sent to all the ports (except received Interface)
- ARP binding ARP -s IP address MAC address
- Access external networks: not in the same broadcast domain
- Access Gateway: requires an IP address and MAC ARP broadcast to obtain the gateway MAC address
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RARP
- MAC->IP
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IGMP
- Multicast protocols added
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Header
- version
- V4 version of the popular
- V6 version of the next generation
- Packet length
- The total length
- Packet slice
- MTU value: Test Method packet size ping -l -f (ip address slice is not allowed) under Windows
- Flag 0 can slice, sliced 1 can not
- The TTL
- Packet survival time in the three-tier equipment
- TTL can be inherited
- Traceroute
- tracert -d ip address
- version
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Transport Layer
- TCP: Reliable connection-oriented concept is built on top of virtual pipe network layer
- UDP: unreliable immediacy
- Live platform
- UDP: Voice + Video
- TCP: Public Forums screen
- TCP protocol port number: 3389,23,22,80,443,25,110
- UDP protocol port number: 53
- How to view the port numbers: netstart -nao find "14.215.177.39/ port number" test port numbers connectivity (blocked by a firewall)
- TCP three-way handshake / sliding four break windows, etc.