Sonic Network Infrastructure

You'll notice that the connection between our 3 main switches (Switch1, Switch2, and Switch3) is "redundant". That means that if we were to lose any one of those connections, all devices would still be able to communicate with each other. These connections are also at 100 Mbps in "Full Duplex" mode. See below for further explanations of these devices.

Cisco 7010 (Mega): This is our main router. It serves as a "gateway" between our local network and the Internet (as well as other local networks like NapaNet).

Definition: A device that routes data packets from one local area network (LAN) or wide area network (WAN) to another. Routers see the network as network addresses and all the possible paths between them. They read the network address in each transmitted frame and make a decision on how to send it based on the most expedient route (traffic load, line costs, speed, bad lines, etc.). Routers work at the network layer (OSI layer 3), whereas bridges and switches work at the data link layer (layer 2).

As well as performing actual routing and path determination, routers are also used for such functions as segmenting LANs to balance traffic, filtering traffic for security purposes and controlling broadcast storms. Multi protocol routers support several protocols such as IPX, TCP/IP and DECnet.

Routers often serve as an Internet backbone, interconnecting all networks in the enterprise. This architecture strings several routers together via a LAN topology such as FDDI. Another approach uses a router with a high-speed backplane known as a collapsed backbone. The collapsed backbone router, which connects more subnetworks in one device, makes network management simpler. The substitution of a fast backplane instead of an external LAN topology improves performance.

Routers can only route a message that is transmitted by a routable protocol such as IPX and IP. Messages in non-routable protocols, such as NetBIOS and LAT, cannot be routed, but they can be transferred from LAN to LAN via a bridge. Because routers have to inspect the network address in the protocol, they do more processing and add more overhead than a bridge or switch, which both work at the data link (MAC) layer.

Most routers are specialized computers that are optimized for communications; however, router functions can also be implemented by adding routing software to a file server. NetWare, for example, includes routing software. The NetWare operating system can route from one subnetwork to another if each one is connected to its own network adapter (NIC) in the server. The major router vendors are Cisco Systems and Bay Networks.

Usage: This device handles all of our off site connections which include a DS3 circuit to UUNet, a T1 to MCI, a T1 to Sprint, a T1 to NapaNet, and a Frame Relay circuit to NBN.

Firewall Router (Blam & Slam): These two routers manage all the connections we serve to other occupants in our building and serve as Firewalls.

Definition: Same as above.

LinkSwitch 3000 (Switch3): This is an Ether Switch that works with 10 and 100 Mbps connections.

Definition: A network device that cross connects stations or LAN segments. LAN switches are available for Ethernet, Fast Ethernet, Token Ring and FDDI. A LAN switch is also known as a frame switch. ATM switches are generally considered a category by themselves.

Network switches are increasingly replacing shared media hubs in order to increase bandwidth. For example, a 16-port 10BaseT hub shares the total 10 Mbps bandwidth with all 16 attached nodes. By replacing the hub with a switch, each sender and receiver has the full 10 Mbps capacity. Each port on the switch can give full bandwidth to a single server or client station or to a hub with several stations.

Usage: This device has several of our servers attached to it including Ultra, Thunder, and Fridge, along with the two Linux-based Routers. The links between all Switches on our network are 100 Mbps Ethernet at Full Duplex, which gives an effective throughput of 200 Mbps.

LinkSwitch 1000 (Switch1, Switch2, & Switch4): This is an Ether Switch that works mainly with 10 Mbps connections, but also has one 100Mbps port.

Definition: Same as above.

Usage: Switch1 and Switch2 have several of our servers attached, as well as all of the Terminal Servers (devices that communicate between the modems and the network). Switch4 serves the Sonic staff.

LinkBuilder FMS II (Hub #1): This is an Ethernet Concentrator. It allows us to hook up several computers together in a network.

Definition: A central connecting device in a network that joins communications lines together in a star configuration. Passive hubs are just connecting units that add nothing to the data passing through them. Active hubs, also sometimes called multiport repeaters, regenerate the data bits in order to maintain a strong signal, and intelligent hubs provide added functionality.

Hubs are mandatory in 10BaseT twisted pair Ethernet as well as Token Ring networks. They are also used to replace the daisy chain cabling in 10Base5 and 10Base2 coaxial Ethernets in order to improve network management.

In Token Rings, the hub is called a MAU (Multi-station Access Unit). Multiple media hubs interconnect different types of Ethernets (twisted pair, coax and optical fiber) and can bridge between Ethernet, Token Ring, FDDI and ATM topologies. Switching hubs provide Ethernet and ATM switching.

Hubs have become very intelligent, modular and customizable, allowing for the insertion of bridging, routing and switching modules all within the same unit. A hub can even host a CPU board and network operating system, turning the hub into a file server or some type of network control processor that performs LAN emulation or other complex function as networks grow.

Usage: This hub, along with Switch4, serves all the connections for our staff.

PS40 Port Switch Hub (PS40): This is another Ethernet Concentrator, but this one is "segmentable", which means that we can separate the ports on this hub into groups that will only pass on information to the other groups or devices when necessary.

Definition: Same as above.

Usage: We use this hub for troubleshooting various problems on our network.

Other Definitions:

Gateway: A computer that performs protocol conversion between different types of networks or applications. For example, a gateway can convert a TCP/IP packet to a NetWare IPX packet and vice versa, or from AppleTalk to DECnet, from SNA to AppleTalk and so on.

Gateways function at layer 4 and above in the OSI model. They perform complete conversions from one protocol to another rather than simply support one protocol from within another, such as IP tunneling. Sometimes routers can implement gateway functions.

An electronic mail, or messaging, gateway converts messages between two different messaging protocols.

Full Duplex Ethernet: An extension to 10BaseT Ethernet that is implemented in a switched Ethernet environment, which has a dedicated line between the station and switch. It is built into the network adapter (NIC) and switch, providing bi-directional transmission that boosts bandwidth from 10 to 20 Mbps, or from 100 to 200 Mbps.

DS3 Circuit: (Digital Signal) A classification of digital circuits. The DS technically refers to the rate and format of the signal, while the T designation refers to the equipment providing the signals. In practice, "DS" and "T" are used synonymously; for example, DS1 and T1, DS3 and T3.

                   NORTH AMERICA, JAPAN, KOREA, ETC.

                  Service   Channels    Speed

                     DS0        1        64 Kbps  (voice)

                     DS1       24     1.544 Mbps  (T1)

                     DS1C      48     3.152 Mbps  (T1C)

                     DS2       96     6.312 Mbps  (T2)

                     DS3      672    44.736 Mbps  (T3)

                     DS4     4032   274.176 Mbps  (T4)

OSI: (Open System Interconnection) An ISO standard for worldwide communications that defines a framework for implementing protocols in seven layers. Control is passed from one layer to the next, starting at the application layer in one station, proceeding to the bottom layer, over the channel to the next station and back up the hierarchy.

At one time, most vendors agreed to support OSI in one form or another, but OSI was too loosely defined and proprietary standards were too entrenched. Except for the OSI-compliant X.400 and X.500 e-mail and directory standards, which are widely used, what was once thought to become the universal communications standard now serves as the teaching model for all other protocols.

Most of the functionality in the OSI model exists in all communications systems, although two or three OSI layers may be incorporated into one.

Firewall: A network node set up as a boundary to prevent traffic from one segment to cross over to another. Firewalls are used to improve network traffic as well as for security purposes. A firewall may be implemented in a router or it may be a device specialized for such purposes.

All definitions above taken from the TechWeb Technology Encyclopedia.