Network+ (N10-008)

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OSI Model Layers
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Terms in this set (58)
OSI Model Layers
Application
Presentation
Session
Transport
Network
Data Link
Physical
Will OSI Model Layers communicate with different layers
No, only talk to the same layer on the other device.
Can OSI Layer 2 communicate will layer 5
No, OSI Layers can only communicate with layers one above or below.
What is the Purpose of the OSI Model
Provide a model to describe how data moves from source device to destination device.
What are the responsibilities of Layer 1 of the OSI Model
Transmission of bits over medium.
What is the Physical medium that Layer 1 of the OSI model use to transmit data.
Cables, Connectors, NIC, Repeaters, and Hubs
What is the Responsibilities of the Data Link Layer.
For Node to Node delivery & creates frames & Physical Address ( MAC Address).
What does the Data Link Layer responsible to control
Access, Flow, and Error
Describe Transmission Control's function
Establishing & Terminating, Media Access Management, Flow Control, Error Control, Access Control.
What does the logical link control (LLC) sublayer of the data link layer determines?
To use either the connectionless or connection - oriented.
What are the basic functions of the Network LayerPacket Addressing, Address Conversion, Source-to-Destination Delivery, & Routing.Does a router determine the best path to destination?YesDoes the Router provide physical or logical connections for the networkIt Provides Logical Address schemePacketizing at the network layer involvesCreates packet from transport layer, encapsulation, and applied IP address both source and destination.Fragmentation at the network layer doesDivides large packets into smaller ones so it can be sent easier.The responsibilities of the transport layerEnd to end message delivery, error checking, distinguishes application protocol, and adds port value.What are the functions of the transport layerMessage acknowledgment, session multiplexing, and service point addressWhat are the two major protocols in the transport layer.User datagram protocol (UDP) & Transmission Control Protocol (TCP)What are the characteristics of connectionless transmissionReceiver doesn't acknowledged receipt of packet, assumed success, faster communicationWhat are the characteristics of connection oriented transmission.Receiver does acknowledge receipt of packet.Which protocol is used for connectionless transmission.Which protocol is used for connection transmission.TCPWhat are the steps in the three way handshake / connection oriented transmissionAck, syn/ack, synWhat are responsibilities for the Session LayerFor communication between 2 devices, and regulates the flow of data between them, and manages the transfer of data.What are some of the functions of the Session LayerSession Establishment, maintenance, and termination; Session Support, security, name recognition and login.Dialog Control what are the three types.Simplex, Half Duplex, Full DuplexHalf DuplexCommunication between two devices whereby transmission takes place in only one direction at a time.SimplexA type of transmission in which signals may travel in only one direction over a medium at once.Full DuplexCommunication that happens in two directions at the same time.What are the protocols used by the session layerNet-Bois, RPC,DNS,NFSWhat are the responsibilities of the Presentation LayerTo Translates data into common format known to application layer at receiving station.What are the functions of the Presentation LayerCharacter Code Translation, Data Conversion, Data Compression, Encryption.Give a example of Character Code TranslationASCIILayer 7 - ApplicationClosest to the user. Provides network services to the applications of the user, such as email, file transfer, terminal emulation, and Browsers.Layer 7 - Application ProtocolsSTMP, FTP, HCP, DNS, HTTPSEthernet/ IP Headers PurposeAddressing & StructureEthernet Frame Format1. Preamble: 7 Bytes; An alternating 1,0 pattern provides a 5 MHz clock at the start of each packet, which allows the receiving devices to lock the incoming bit stream 2. Start Frame Delimiter (SFD)/Synch: 1 Byte; The preamble is seven octets and the SFD is one octet (synch); The SFD is 10101011, where the last pair of 1s allows the receiver to come into the alternating 1,0 pattern somewhere in the middle and still sync up to detect the beginning of the data 3. Destination Address (DA): 6 Bytes; This transmits a 48-bit value using the least significant bit (LSB) first; Used by receiving stations to determine whether an incoming packet is addressed to a particular node; Can be an individual address or a broadcast or multicast MAC address; A broadcast is all 1s—all Fs in hex— and is sent to all devices; A multicast is sent only to a similar subset of nodes on a network 4. Source Address (SA): 6 Bytes; a 48-bit MAC address used to identify the transmitting device, and it uses the least significant bit first; Broadcast and multicast address formats are illegal within the SA field 5. Length or Type: 2 Bytes; 802.3 uses a Length field, but an Ethernet_II frame uses a Type field to identify the Network layer protocol; The old, original 802.3 cannot identify the upper-layer protocol and must be used with a proprietary LAN—IPX, for example 6. Data: 46 - 1500 Bytes (Packet); A packet sent down to the Data Link layer from the Network layer; The size can vary from 46 to 1,500 bytes 7. Frame Check Sequence (FCS): 4 Bytes; A field at the end of the frame that's used to store the cyclic redundancy check (CRC) answer; When a receiving host receives the frame and runs the CRC, the answer should be the same; If not, the frame is discarded, assuming errors have occurredIPv4 HeaderMinimum Length is 20 Bytes and Maximum Length is 60 Bytes.What does TCP Flags IndicateState of the connectionTCP FlagsSYN; ACK; FIN; RST; PSH; URGDescribe and Define the ACK TCP FlagAcknowledgment; First Packet to ReceiverDescribe and Define the SYN TCP FlagSynchronization; Starts the MessagesDescribe and Define the FIN TCP FlagFinish; Request Connect terminationDescribe and Define the RST TCP FlagReset; Error in transmissionDescribe and Define the PSH TCP FlagPush; Buffering needs to be controlledDescribe and Define the URG TCP FlagUrgent; Data is forward immediately and notifies receiver to prioritize all packets.PayloadThe Data being transmitted in the transmissionsTypes of PayloadsFixed and VariableFixed PayloadFrames become fixed Size and slightly more efficientVariable PayloadA pattern is used to determine frame size and uses more processing and data per frameMaximum Transmission Unit(MTU)The largest frame or packet size supported over networkThe Pros for using MTUMore Data; Transfer Rates; Enables Jumbo Frames.Cons of MTUCertain routers cant handle it.Window command to determine MTUPing [Name] -f -L xxxx(size)MAC command to determine MTUPing [Name] -d -s xxxx(size)Adjusting MTU SizeWindows: Netsh; Linux: Ifconfig; MAC: ManuallyMaximum Segment Size (MSS)The maximum amount of data that can be grabbed and placed in a segment that a device can handleDetailed Maximum Segment SizeData Segment & Header total Size should be less than MTU Size.