Lab Manual Computer Communication Network Department of Electronics & Telecommunication Engineering St. Vincent Pallotti College of Engineering & Technology CCN Lab Manual SVPCET Experiment 1 Study of CCN components Aim: To study Network Hardware components – Cables, NIC, Repeaters, Hubs, Bridges, Switches, Routers and Gateway. Equipments: 1. Cables - Patch Cables, Rollover Ethernet Cable, Unshielded Twisted Pair (UTP) Cable, Shielded Twisted Pair (STP), Serial Cable, Optical Fiber 2. NIC 3. Repeater 4. Hub 5. Bridge 6. Switch 7. Router 8. Gateway Theory: Cables: 1. Patch Cables A patch cable connects two network devices. Patch cables are typically CAT5 / CAT5e/Cat6 Ethernet cables linking a computer to a nearby network hub, switch or router. The connector is called RJ45. Ethernet patch cables are useful to those building home computer networks and also to travelers who need wired access to Internet connections. They are normally manufactured using stranded rather than solid conductors in order to give them pliability that reduces risk of breakage when unplugging or carrying them. CAT5 Standard Patch Cord 1 CCN Lab Manual SVPCET 10 BASE T represents 10 Mbps Baseband signalling Twisted pair cable. Other options are, 100 BASE T, 1000 BASE T. For 10 Base T and 100 Base T only 4 pins are used. 1000 Base T uses 4 pairs and uses all pins and CAT6 cable is required. 2. Rollover Ethernet Cable: A crossover cable directly connects two network devices of the same type to each other over Ethernet. Ethernet crossover cables are commonly used when temporarily networking two devices in situations where a network router, switch or hub is not present. 3. Unshielded Twisted Pair (UTP) Cable: Twisted pair cabling comes in two varieties: shielded and unshielded. Unshielded twisted pair (UTP) is the most popular and is generally the best option for school networks. The quality of UTP may vary from telephone-grade wire to extremely high-speed cable. The cable has four pairs of wires inside the jacket. Each pair is twisted with a different number of twists per inch to help eliminate interference from adjacent pairs and other electrical devices. The tighter the twisting, the higher the supported transmission rate and the greater the cost per foot. The EIA/TIA (Electronic Industry Association/Telecommunication Industry Association) has established standards of UTP and rated six categories of wire. Unshielded Twisted Pair (UTP) Cable 2 CCN Lab Manual SVPCET 4. Shielded Twisted Pair (STP): Although UTP cable is the least expensive cable, it may be susceptible to radio and electrical frequency interference (it should not be too close to electric motors, fluorescent lights, etc.). If you must place cable in environments with lots of potential interference, or if you must place cable in extremely sensitive environments that may be susceptible to the electrical current in the UTP, shielded twisted pair may be the solution. Shielded cables can also help to extend the maximum distance of the cables. Shielded twisted pair cable is available in three different configurations. Each pair of wires is individually shielded with foil. There is a foil or braid shield inside the jacket covering all wires (as a group). There is a shield around each individual pair, as well as around the entire group of wires (referred to as double shield twisted pair). Shielded Twisted Pair (STP) 5. Serial Cable: This port connects a PC to an external modem, serial mouse, etc. DOS calls these ports COM1- COM4. The small version is slightly more popular than the large version. Both the small (male DB-9) and large (male DB-25) versions are electrically identical, and can be interchanged with a simple adapter. They both speak RS-232, a relatively slow (around 105Kbps max) and error- prone protocol. The default controller is CPU-intensive and low data rate. A better UART, common on modern machines, is the 16550A, which has a 1KB buffer. Serial Cable 6. Optical Fiber: 3 CCN Lab Manual SVPCET Fiber optic cabling consists of a centre glass core surrounded by several layers of protective materials. A plastic coating then cushions the fiber centre help to strengthen the cables and prevent breakage. It transmits light rather than electronic signals eliminating the problem of electrical interference. This makes it ideal for certain environments that contain a large amount of electrical interference. It has also made it the standard for connecting networks. Fiber optic cables have the ability to transmit signals over much longer distances than coaxial and twisted pair. It also has the capability to carry information at vastly greater speeds. This capacity broadens communication possibilities to include services such as video conferencing and interactive services. The cost of fiber optic cabling is comparable to copper cabling. Optical Fiber NIC – Network Interface Card: A network card, network adapter or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network. It provides physical access to a networking medium and often provides a low-level addressing system through the use of MAC addresses. It allows users to connect to each other either by using cables or wirelessly. The NIC provides the transfer of data in megabits. On modern PCs, NIC is integrated into the motherboard. Repeater: 4 CCN Lab Manual SVPCET A repeater is an electronic device that receives a signal and retransmits it at a higher power level, or to the other side of an obstruction, so that the signal can cover longer distances without degradation. In most twisted pair Ethernet configurations, repeaters are required for cable runs longer than 100 meters away from the computer. Repeater Hub: A hub contains multiple ports. When a packet arrives at one port, it is copied to all the ports of the hub for transmission. When the packets are copied, the destination address in the frame does not change to a broadcast address. It does this in a rudimentary way: It simply copies the data to all of the Nodes connected to the hub. Hub Bridge: A network bridge connects multiple network segments at the data link layer (layer 2) of the OSI Model. Bridges do not promiscuously copy traffic to all ports, as hubs do, but learn which MAC addresses are reachable through specific ports. Once the bridge associates a port and an address, it will send traffic for that address only to that port. Bridges learn the association of ports and addresses by examining the source address of frames that it sees on various ports. Once a frame arrives through a port, its source address is stored and the bridge assumes that MAC address is associated with that port. The first time that a previously unknown destination address is seen, the bridge will forward the frame to all ports other than the one on which the frame arrived. Bridges come in three basic types: 5 CCN Lab Manual SVPCET 1. Local bridges: Directly connect local area networks (LANs) 2. Remote bridges: Can be used to create a wide area network (WAN) link between LANs. Remote bridges, where the connecting link is slower than the end networks, largely have been replaced by routers. 3. Wireless bridges: Can be used to join LANs or connect remote stations to LANs. Bridge Switch: A switch is a device that forwards and filters OSI layer 2 datagram between ports based on the MAC addresses in the packets. This is distinct from a hub in that it only forwards the datagram to the ports involved in the communications rather than all ports connected. A switch is not capable of routing traffic based on IP address (layer 3) which is necessary for communicating between network segments or within a large or complex LAN. Some switches are capable of routing based on IP addresses but are still called switches. A switch normally has numerous ports, with the intention being that most or the entire network is connected directly to the switch, or another switch that is in turn connected to a switch. Switch is a marketing term that encompasses routers and bridges, as well as devices that may distribute traffic on load or by application content (e.g., a Web URL identifier). Switches may operate at one or more OSI model layers, including physical, data link, network, or transport (i.e., end-to-end). Switch Router: 6 CCN Lab Manual SVPCET Routers are networking devices that forward data packets between networks using headers and forwarding tables to determine the best path to forward the packets. Routers work at the network layer of the TCP/IP model or layer 3 of the OSI model. Routers also provide interconnectivity between like and unlike media. This is accomplished by examining the Header of a data packet, and making a decision on the next hop to which it should be sent. They use preconfigured static routes, status of their hardware interfaces, and routing protocols to select the best route between any two subnets. A router is connected to at least two networks, commonly two LANs or WANs or a LAN and its ISP's network. Some DSL and cable modems, for home (and even office) use, have been integrated with routers to allow multiple home/office computers to access the Internet through the same connection. Many of these new devices also consist of wireless access points or wireless routers to allow for IEEE 802.11g/b/n wireless enabled devices to connect to the network without the need for cabled connections. Router 7 CCN Lab Manual SVPCET Gateway: Gateway is used to connect independent networks. A gateway is a protocol convertor. It operates in all the 7 layers of OSI Model. A gateway can accept a packet formatted for one protocol (ex: TCP/IP) and convert it to a packet formatted for another protocol (ex: Apple Talk) before forwarding it.