LAN Devices  Purposes: Dividing the network into subnets Dividing the network into subnets Joining two networks together Joining two networks together  Connectivity Devices Repeaters Repeaters Hubs Hubs Bridges Bridges Switches Switches Routers Routers Gateways Gateways

Repeaters Overview  Working in the physical Layer  Segments must use the same protocol  Segments don’t have to use same cables

Use Repeaters When:  Joining two segments use different cable  Regenerating signal  Joining segments inexpensively

Hubs

What Is a Bridge?  A data-link layer device that connects networks and filters packets Propagates only packets destined for the other side of the bridge Propagates only packets destined for the other side of the bridge Can reduce network traffic and collisions Can reduce network traffic and collisions Can lessen delays Can lessen delays

How Bridges Works  Listen to all packets in the network  Check Source & Destination MAC Address

Bridges and Broadcasts  Bridges propagate all broadcast packets without filtering them.  The network segments on either side of a bridge are in the same broadcast domain.

Bridge Types  Local bridge. Connects network segments of the same type and at the same location  Translation bridge. Connects network segments at the same location that use different media or different protocols  Remote bridge. Connects network segments at remote locations, using a wide area network (WAN) link

Switches  Hub with built-in bridge  Works in Data-Link Layer  Passes Packet to the destination only

Switch Types  A cut-through switch begins to forward packets immediately.  A store-and-forward switch waits until the entire packet arrives before forwarding it.

Routers  Works in Network Layer  Use Routing Protocols  Can be a PC with OS supports routing  Works Like Bridge but more Smarter

Router Types  Routers can be stand-alone hardware devices or software running on a computer. Hardware routers. Range from expensive rack-mounted devices to small stand-alone units Hardware routers. Range from expensive rack-mounted devices to small stand-alone units Software routers. Include Microsoft Windows 2000 Internet Connection Sharing (ICS), and Routing and Remote Access Software routers. Include Microsoft Windows 2000 Internet Connection Sharing (ICS), and Routing and Remote Access

How Routers Work

Routing Tables  Routing tables are essential to the router operation and functions.  There are two methods of creating routing tables: Static routing. Manual creation of routing table entries by an administrator Static routing. Manual creation of routing table entries by an administrator Dynamic routing. Automatic creation of routing table entries by using a specialized routing protocol Dynamic routing. Automatic creation of routing table entries by using a specialized routing protocol

Routers Properties  Removes Data-link layer data  Can connect different networks like Ethernet & Token Ring

Routers Properties [cont.]  Don’t let Corrupted data out  Works with network address  Listens to different segment to avoid High traffic paths

 Bridging Bridges selectively relay packets between network segments, depending on their data-link layer destination addresses. Bridges selectively relay packets between network segments, depending on their data-link layer destination addresses. Bridges maintain a single broadcast domain and create separate collision domains. Bridges maintain a single broadcast domain and create separate collision domains.  Switching Switches improve on the function of bridges by forwarding packets only to their destination systems. Switches improve on the function of bridges by forwarding packets only to their destination systems. Switches reduce the collisions on a network and increase the bandwidth available to each computer. Switches reduce the collisions on a network and increase the bandwidth available to each computer.  Routing Routers are used to connect networks together at the network layer of the OSI reference model. Routers are used to connect networks together at the network layer of the OSI reference model. Routers strip away the data-link layer frame of incoming packets and build a new frame using the data-link layer protocol of the outgoing network. Routers strip away the data-link layer frame of incoming packets and build a new frame using the data-link layer protocol of the outgoing network. Routing tables can be created manually by a network administrator or automatically by a routing protocol. Routing tables can be created manually by a network administrator or automatically by a routing protocol.

Gateways  Connect totally different network Protocols Protocols Data format Data format Languages Languages Network Architecture Network Architecture  Mainly used to Connect PCs with Main Frames Example: Windows NT server to SNA Gateway Example: Windows NT server to SNA Gateway

Gateways work  Removes all Frame information Gateways may be specific hardware or a dedicated PC

Demonstration  Your instructor will show you movie file, that shows a Packet journey