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Application layer - integrates network function into the host operating system, and enables network services Doesn't not include specific applications that provide services, but rather provides the capability for services to operate on the network...HTTP Presentation (Layer 6) - layer formats or "presents" data into a compatible form for receipt by the Application layer or the destination system. Specifically, the Presentation layer ensures: Formatting and translation of data between systems. Negotiation of data transfer syntax between systems, through converting character sets to the correct format. Encapsulation of data into message envelopes by encryption and compression. Restoration of data by decryption and decompression. Session (Layer 5) - primary function is managing the sessions in which data is transferred. Functions at this layer include: Management of multiple sessions (each client connection is called a session). A server can concurrently maintain thousands of sessions. Assignment of the session ID number to each session to keep data streams separate. Set up, maintain, and tear down communication sessions. Transport (Layer 4) - provides a transition between the upper and lower layers of the OSI model, making the upper and lower layers transparent from each other. Transport layer functions include: End-to-end flow control. Port and socket numbers. Segmentation, sequencing, and combination. Connection services, either reliable (connection-oriented) or unreliable (connectionless) delivery of data. Data is referred to as a segment. Network (Layer 3) -
describes how data is routed across networks and on to the destination. Network layer functions include: Identifying hosts and networks using logical addresses. Maintaining a list of known networks and neighboring routers. Determining the next network point to which data should be sent. Routers use a routing protocol to take into account various factors such as the number of hops in the path, link speed, and link reliability to select the optimal path for data. Data is referred to as a packet. Data Link (Layer 2) - Logical Link Control (LLC) Media Access Control (MAC) defines the rules and procedures for hosts as they access the Physical layer. These rules and procedures specify or define: How hosts on the network are identified (physical or MAC address). How and when devices can transmit on the network medium (media access control and logical topology). How to verify that the data received from the Physical layer is error free (parity and CRC). How devices control the rate of data transmissions between hosts (flow control). Data is referred to as a frame. Physical (Layer 1) - sets standards for sending and receiving electrical signals between devices. Protocols at the Physical layer identify: How digital data (bits) are converted to electric pulses, radio waves, or pulses of lights. Specifications for cables and connectors. The physical topology. Data is referred to as bits. he TCP/IP model incorporates the general concepts and structure of the OSI model. The layers of the TCP/IP model are as follows: - Application Host-to-host
Requires less cable than the star Can be difficult to isolate cabling problems A broken cable anywhere breaks the termination and prevents communications between any device on the network. Ring - connects neighboring nodes until they form a ring. Signals travel in one direction around the ring. In ring topologies, each device on the network acts as a repeater to send the signal to the next device. With a ring: Installation requires careful planning to create a continuous ring. Isolating problems can require going to several physical locations along the ring. A malfunctioning node or cable break can prevent signals from reaching nodes further along on the ring. Star - a hub or switch to concentrate all network connections to a single physical location. Today it is the most popular type of topology for a LAN. With the star: All network connections are located in a single place, which makes it easy to troubleshoot and reconfigure. Nodes can be added to or removed from the network easily. Cabling problems usually affect only one node. Requires more cable than any other topology. Every node has its own cable. Mesh - exists when there are multiple paths between any two nodes on a network. created using point-to- point connections. This increases the network's fault tolerance because alternate paths can be used when one path fails. Two variations of topologies exist: Partial --Some redundant paths exist. Full --Every node has a point-to-point connection with every other node. Full topologies are usually impractical because the number of connections increases dramatically with every new node added to the network. However, a full topology becomes more practical through the implementation of an ad-hoc wireless network. With this topology, every wireless network card can communicate directly with any other wireless network card on the network. A separate and dedicated network interface and cable for each host on the network is not required.
Logical Topology [Bus] Physical Topology bus/star - Messages are sent to all devices connected to the bus. Logical Topology [Ring] ring/star - Messages are sent from device-to-device in a predetermined order until they reach the destination device. Logical Topology [star] - Messages are sent directly to (and only to) the destination device. Web browsing Protocol - HyperText Transfer Protocol (HTTP) HTTP over SSL (HTTPS) HyperText Transfer Protocol (HTTP) - is used by Web browsers and Web servers to exchange files (such as Web pages) through the World Wide Web and intranets. can be described as an information requesting and responding protocol. It is typically used to request and send Web documents, but is also used as the protocol for communication between agents using different TCP/IP protocols. HTTP over SSL (HTTPS) - is a secure form of HTTP that uses SSL to encrypt data before it is transmitted. Security protocols - Transport Layer Security (TLS) Transport Layer Security (TLS). -
E-mail Protocol - Simple Mail Transfer Protocol (SMTP) Post Office Protocol 3 (POP3) Simple Mail Transfer Protocol (SMTP) - is used to route electronic mail through the internetwork. is used: Between mail servers for sending and relaying mail. By all e-mail clients to send mail. By some e-mail client programs, such as Microsoft Outlook, for receiving mail from an Exchange server. Post Office Protocol 3 (POP3) - is part of the TCP/IP protocol suite and is used to retrieve e-mail from a remote server to a local client over a TCP/IP connection. With POP3, e-mail messages are downloaded to the client. An e-mail client that uses POP3 for receiving mail uses SMTP for sending mail. Network services Protocol - Dynamic Host Configuration Protocol (DHCP)Domain Name System (DNS) Network Time Protocol (NTP) Lightweight Directory Access Protocol (LDAP) Dynamic Host Configuration Protocol (DHCP - s a method for automatically assigning addresses and other configuration parameters to network hosts. Using a DHCP server, hosts receive configuration information at startup, reducing the amount of manual configuration required on each host. Domain Name System (DNS) - s a system that is distributed throughout the internetwork to provide address/name resolution. For example, the name www.mydomain.com would be identified with a specific IP address. Network Time Protocol (NTP) -
is used to communicate time synchronization information between systems on a network. Lightweight Directory Access Protocol (LDAP - used to allow searching and updating of a directory service. The LDAP directory service follows a client/server model. One or more LDAP servers contain the directory data, the LDAP client connects to an LDAP Server to make a directory service request. Network management Protocol - Simple Network Management Protocol (SNMP) Remote Terminal Emulation (Telnet) Secure Shell (SSH) Simple Network Management Protocol (SNMP) - s a protocol designed for managing complex networks. SNMP lets network hosts exchange configuration and status information. This information can be gathered by management software and used to monitor and manage the network. Remote Terminal Emulation (Telnet) - allows an attached computer to act as a dumb terminal, with data processing taking place on the TCP/IP host computer. It is still widely used to provide connectivity between dissimilar systems. Telnet can also be used to test a service by the use of HTTP commands. Secure Shell (SSH) - allows for secure interactive control of remote systems. SSH uses RSA public key cryptography for both connection and authentication. SSH uses the IDEA algorithm for encryption by default, but is able to use Blowfish and DES. SSH is a secure and acceptable alternative to Telnet. Transport protocols - Transmission Control Protocol (TCP) User Datagram Protocol (UDP) Transmission Control Protocol (TCP) -
PVC or plenum plastic insulation surrounds each wire. Plenum cable is fire resistant and non- toxic. It must be used when wiring above ceiling tiles. PVC cable cannot be used to wire above ceilings because it is toxic when burned. Twisted pair - Two wires are twisted to reduce the effects of electromagnetic interference (EMI) and crosstalk. Because the wires are twisted, EMI should affect both wires equally and can be cancelled out. Twisted pair - Multiple wire pairs are bundled together in an outer sheath. Twisted pair cable can be classified according to the makeup of the outer sheath: Shielded Twisted Pair (STP) has a grounded outer copper shield around the bundle of twisted pairs or around each pair. This provides added protection against EMI. Unshielded Twisted Pair (UTP) does not have a grounded outer copper shield. UTP cables are easier to work with and are less expensive than shielded cables. Phone cable - RJ- Used to connect a PC to a phone jack in a wall outlet to establish a dial-up Internet connection. Has two pairs of twisted cable (a total of 4 wires). Cat 3 - RJ- Designed for use with 10 megabit Ethernet or 16 megabit token ring. Cat 5 - RJ- Supports 100 megabit Ethernet and ATM networking. Cat 5 specifications also support gigabit (1000 Mb) Ethernet. Cat 5e - RJ- Similar to Cat 5 but provides better EMI protection. Supports 100 megabit and gigabit Ethernet.
Cat 6 - RJ- Supports 10 gigabit Ethernet and high-bandwidth, broadband communications. Cat 6 cables often include a solid plastic core that keeps the twisted pairs separated and prevents the cable from being bent too tightly. Additional standards for Cat 6 include Cat 6a (advanced) and Cat 6e (enhanced) which provide better protection against EMI. RJ-11 - Has 4 connectors Supports up to 2 pairs of wires Uses a locking tab to keep connector secure in outlet Used primarily for telephone wiring RJ-45 - Has 8 connectors Supports up to 4 pairs of wires Uses a locking tab to keep connector secure in outlet Used for Ethernet and some token ring connections Coaxial cable - Two concentric metallic conductors: The inner conductor, which carries data signals. It is made of copper or copper coated with tin. The mesh conductor is a second physical channel that also grounds the cable. It is made of aluminum or copper coated tin. Coaxial cable - The insulator, which surrounds the inner conductor, keeps the signal separated from the mesh conductor. It is made of PVC plastic. Coaxial cable -
10Base5 Ethernet networking (also called Thicknet) F-Type - Twisted onto the cable Used to create cable and satellite TV connections Used to connect a cable modem to a broadband cable connection BNC - Molded onto the cable Used in 10Base2 Ethernet networks AUI - Is a DB15 serial connector Used in 10Base5 Ethernet networks fiber optic cables - you need two fiber strands. One strand transmits signals, and the other strand receives signals. fiber optic cables is composed of the following components - The core carries the signal. It is made of plastic or glass. The cladding maintains the signal in the center of the core as the cable bends. The sheathing protects the cladding and the core. fiber optic cabling offers the following advantages - Totally immune to EMI (electromagnetic interference) Highly resistant to eavesdropping Supports extremely high data transmission rates Allows greater cable distances without a repeater Fiber optic cabling offers the following disadvantages: - Very expensive Difficult to work with
Special training required to attach connectors to cables Multi-mode and single mode fiber cables are - distinct from each other and not interchangeable. Single Mode - Transfers data through the core using a single light ray (the ray is also called a mode) The core diameter is around 10 microns Supports a large amount of data Cable lengths can extend a great distance Multi-mode - Transfers data through the core using multiple light rays The core diameter is around 50 to 100 microns Cable lengths are limited in distance ST Connector - Used with single and multi-mode cabling ST Connector - Keyed, bayonet-type connector ST Connector - Also called a push in and twist connector ST Connector - Each wire has a separate connector ST Connector -
A single connector with two ends keeps the two cables in place LC Connector - Uses a ceramic ferrule to insure proper core alignment and prevent light ray deflect LC Connector - Half the size of other fiber-optic connectors MT-RJ Connector - Used with single and multi-mode cabling MT-RJ Connector - Composed of a plastic connector with a locking tab MT-RJ Connector - Uses metal guide pins to ensure it is properly aligned MT-RJ Connector - A single connector with one end holds both cables MT-RJ Connector - Uses a ceramic ferrule to insure proper core alignment and prevent light ray deflection straight-through - Computers connect to the network through a hub or switch with a straight-through cable. There are two standards for creating straight-through cables: T568A -
to use this standard, arrange the wires from pins 1 to 8 in each connector in the following order: GW, G, OW, B, BW, O, BrW, Br. T568B - To use this standard, arrange the wires from pins 1 to 8 in each connector in the following order: OW, O, GW, B, BW, G, BrW, Br. Cross-over - Computers can connect directly to one another using a crossover cable. The easiest way to create a crossover cable is to arrange the wires in the first connector using the T568A standard and arrange the wires in the second connector using the T568B standard. Tx+ - is a pin used for transmitting Rx - is a pin used for receiving Ethernet specifications use the following pins - Pin 1: Tx+ Pin 2: Tx- Pin 3: Rx+ Pin 4: Unused Pin 5: Unused Pin 6: Rx- Pin 7: Unused Pin 8: Unused Be aware of the following when making cables for Ethernet: - Use a crimping tool designed for RJ-45 connectors to attach connectors to UTP cable. Cat 5/5e/6/6a cables come with wires that have solid cores or stranded cores. Use solid core cables for longer runs inside walls or the ceiling; use stranded wires for drop cables where flexibility and frequent movement occurs.
connects the MDF on the main floor to IDFs on upper floors. Cabling runs vertically (up and down) between the MDF and the IDFs. Horizontal cross connect - connects IDFs on the same floor. Cabling runs horizontally (sideways) between the IDFs. 25 pair - 25 pair cables consist of 25 pairs of copper wires in a single bundle (containing a total of 50 wires). 25 pair cables are often used for telephone installations that have multiple telephone lines, to replace multiple Cat3/5/5e/6 cables in a single bundle, and for horizontal and vertical cross connects between the MDF and IDFs. Individual wires within the 25 pair cable use the following color coding scheme: RJ-21 connector - is used to connect 25 pair cable to other wiring devices, or you can manually connect each wire to the necessary location. 100 pair - consists of 100 pairs of copper wires in a single bundle (containing 200 wires). 100 pair wires use the same coloring scheme as 25 pair wires, repeated 4 times. Each bundle of 25 wires is often wrapped together with a colored nylon string to help separate wires of the same color. 25 pair coloring scheme - A total of 10 colors are used in two different groups: Group 1 colors are white, red, black, yellow, and violet. Group 2 colors are blue, orange, green, brown, and slate. There are 5 wires of each color. Every colored wire in group 1 is paired with each color in group 2. For example, you will have the following pairs for the white wires: White with blue White with orange White with green
White with brown White with slate 66 block - punchdown block used for connecting individual copper wires together. 66 blocks are 25 rows of four metal pins. Pushing a wire into the pin pierces the plastic sheath on the wire, making contact with the metal pin. used primarily for telephone applications 66 blocks data applications - straght blade Be sure to purchase 66 blocks rated for Cat5. When inserting wires in the block, place both wires in a pair through the same slot to preserve the twist as much as possible. two different 66 block configurations: - With the 25 pair block (also called a non-split block), all 4 pins are bonded (electrically connected). Use the 25 pair block to connect a single wire with up to 3 other wires. With the 50 pair block (also called a split block), each set of 2 pins in a row are bonded. The left pin is connected with the middle left pin, while the right pin is connected with the middle right pin. Use the 50 pair block to connect a single wire to one other wire. 110 block - use a notched blade punchdown block used for connecting individual wires together. The 110 block comes in various sizes for connecting pairs of wires (for example 50, 100, or 300 pair). The 110 block has rows of plastic slots. Each plastic slot connects two wires together: Place the first wire in the plastic slot on the 110 block. Insert a connecting block over the wire and slot. The connecting block has metal connectors that pierce the plastic cable sheath. Place the second wire into the slot on the connecting block. C-4 connectors - connect four pairs of wires
