Multiple aps servicing the same ssid are referred to

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Multiple APs servicing the same SSID are referred to as an Extended Service Set (ESS). A single AP is referred to as a Basic Service Set (BSS). OSI Model Layer Encapsulation Function Services Device 7. Application Data Establishes availability of resources FTP, SMTP, Telnet, POP3 6. Presentation Data Compression, encryption and decryption JPEG, GIF, MPEG, ASCII 5. Session Data Establishes, maintains and terminates sessions NFS, SQL, RPC 4. Transport Segment Establishes end-to-end connection. Uses virtual circuits, buffering, windowing and flow control TCP, UDP, SPX 3. Network Packet Determines best path for packets to take. IP, IPX Router 2. Data Link (LLC MAC) Frame Transports data across a physical connection. Error detection Frame Relay, PPP, HDLC Switch/Bridge 1. Physical Bits Puts data onto the wire Hub/Repeater/ Concentrator/MAU Layers - All People Seem To Need Data Processing. Data formats - D on’t Some People Fry Bacon. 7. Application Layer Provides Services to lower layers. Enables program to program communication and determines if sufficient resources exist for communication. Examples are e-mail gateways (SMTP), TFTP, FTP and SNMP. 6. Presentation Layer Presents information to the Application layer. Compression, data conversion, encryption and standard formatting occur here. Contains data formats JPEG, MPEG, MIDI, TIFF. 5. Session Layer Establishes and maintains communication ‘sessions’ between applications (dialogue control). Sessions can be simplex (one direction only), half-duplex (one direction at a time) or full duplex (both ways simultaneously). Session layer keeps different applications data separate from other applications. Protocols include NFS, SQL, X Window, RPC, ASP, and NetBIOS Names. 4. Transport Layer Responsible for end to end integrity of data transmissions and establishes a logical connection 4 between sending and receiving hosts via ‘virtual circuits’. Windowing works at this level to control
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Cisco CCENT Cram Guide v3.0 © Paul Browning 2017 how much information is transferred before an acknowledgement is required. Data is segmented and reassembled at this layer. Port numbers are used to keep track of different conversations crossing the network at the same time. Supports TCP. UDP, SPX, NBP, Segmentation works here (Segments) and error correction (not detection). 3. Network Layer Routes data from one node to another and determines the best path to take. Routers operate at this level. Network addresses are used here which are used for routing (Packets). Routing tables, subnetting and control of network congestion occur here. Routing protocols regardless of which protocol the run over reside here. IP, IPX, ARP, IGRP, Appletalk. 2. Data Link Layer Sometimes referred to as the LAN layer. Responsible for the physical transmission of data from one node to another. Error detection occurs here. Packets are translated into frames here and hardware address is added. Bridges and switches operate at this layer.
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  • Winter '17
  • James Smith
  • Computer Science, IP address, Paul Browning, Cram Guide v3, CCENT Cram Guide, Cisco CCENT Cram

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