Lesson 5 – Understanding Network Hardware

Repeaters Hubs and concentrators Bridges Routers Switches Gateways Firewalls Short-haul modems OVERVIEW

A repeater: Extends the distance of a Network run. Takes a weak Network signal in on one side, boosts the signal, and sends it out its other side. Operates at the physical layer of the OSI Networking model. REPEATER

A repeater: Is only used to connect the same type of media. Can segment one of its connections from the other. Repeater

Using repeaters to expand Network length

Hubs and concentrators are used to connect Network nodes to Network backbones. Nodes are connected to hubs in a physical star fashion, whether they are used for a star or ring topology Network. HUBS AND CONCENTRATORS

Properties : Hubs echo data from each port to other ports on the hub. They are automatically positioned. Hubs and concentrators

Features : Built-in management. Auto sensing of connection speeds. High-speed up-links connecting the hub to a backbone. Built-in bridging and routing functions. Hubs and concentrators

Bridges A typical hub arrangement

Built-in switching. Bridges connect two Network segments. They have the intelligence to pass traffic from one segment to another. BRIDGES

Bridges that can span different Networking systems and media are also available. They operate at the data link layer of the OSI model. They address information about all parts of your Network. Bridges

Routers operate at the network layer of the OSI Model. They are far more intelligent than bridges in sending incoming packets to their destination. ROUTERS

Routers can translate from any of the protocols at layers 1- 3 to any other protocols at layers 1-3. They can connect similar and dissimilar networks. Routers

Routers become a node on a Network and have their own Network address. They can determine and use the shortest route to a location. They form the backbone of the Internet. Routers

Programming routers: Connect a terminal or PC to the RS-232C port and program the router in text mode. Use the Network-based software to program the router. Routers

Network using routers

Switches can rapidly switch connections from one port to another. They are connection-oriented. SWITCHES

They dynamically switch among ports to create connections. All ports coming into a switch are not part of a single collision domain. Switches

Network using hubs and switches

Gateways are application-specific interfaces. They link the 7 layers of the OSI Model when they are dissimilar at any or all levels. They can translate from Ethernet to Token Ring. GATEWAYS

A firewall sits between two Networks and enforces Network security policies. They generally sit between a company LAN and the Internet. FIREWALLS

Types: Network-based Application-based Firewalls

Short-haul modems : Provide point-to-point connectivity between a workstation and another device. Enable you to connect two distant RS-232C devices to each other. SHORT-HAUL MODEMS

Short-haul modems: Can be used when a computer needs terminal access to a remote device. Are preferred when the two devices often or always need to be connected. Short-haul modems

Short-haul modem connection

Repeaters Hubs and concentrators Bridges Routers Programming routers Switches Gateways Firewalls Short-haul modems SUMMARY