My son is in grade 11 and he wants to know more about these devices - What they are, theire usage and the way they operate ect.
Thanks.
Reverend Andries Nel

I can tell you about routers but not bridges.
There are typically three flavors of routers. Those connected analog modems (directly or through serial ports), ISDN which is what I have which is a digital phone line (128k always), and ethernet which connects to dsl modems, cable modems and internal WideAreaNetworks (WAN). ISPs have a router on a T1 or T3 connection, 24 digital phone lines on a T1, T3 is bigger.
The router has an ethernet on the computer side and may come with a builtin switch (A hub but a little faster)
I turn the ISDN router on first. As each computer is brought up, the router assigns internal (fake) IP addresses to the computers starting with 192.168.0.2 and counts up by 1.
Computer 1 192.168.0.2
Computer 2 192.168.0.3
Computer 3 192.168.0.4
Computer 4 192.168.0.5
Every computer is set to 192.168.0.1 as the gateway (my router).
When I go onto the internet I bring up IE on one of my computers. A Packet that isn't in the 192.168.0.xxx range is sent to the router. The router knows it has to go out for it so dials my ISP twice (2 64k channels --2 second connect time on an ISDN router).
The ISP assigns the router a dynamic Ip address not the computers. Essentially you are like your ISP, multiple computers out one line.
If you spend bucks, you can have multiple static ip addresses passed through one ip address, through the router to each computer.
This allows the computers to become servers. Email, news, music, game, etc.
The bonus of having a router with 192.168.xxx.xxx numbers is that you become hackproof. 192 numbers are not passed through the internet but reflected back by your ISP or router. A tight natural firewall by design.
Every packet that goes out to the net is remembered by the router so it can be returned (ROUTED) back to the computer which sent it.
Another cool feature of the router is that if you get knocked offline, it can redial and continue without you even noticing.

A router is device used to connect 2 or more networks together based on the IP address (172.168.5.21) It uses routing tables based on routing protocols (RIP,OSPF,IGRP) which are shared between routers to determine where and how to send packets(path determination).As it recieves packets in one port it will refer to its table to determine the correct port to send the packet to its destination. This is basically what a router accomplishes. Routers are the primary component for WAN's (Wide Area Networks) ex. Internet. A bridge works within the confines of a LAN (Local Area Network)aka intranet ex. school, company. LAN's connenct workstations, peripherals, terminals, and other devices in a single building or other geographically limted area. A bridge uses the MAC (Media Access Control) address of the node (workstation, network printer, server)any device that has a Network Interface Card which is where the MAC address is burned and then transferred to the systems' registry. The bridge connects 2 segments of a LAN together using the MAC address to send its packets to locate its destination. Bridges cut down on collisions (when 2 packets from different communicating devices collide on a line and destroying ea. other). I hope this helps you and your son out. If your son is interested in the devices and standards of networking I suggest checking out CISCO. I myself am enrolled in the First year curriculum and have completed 2 of the 4 semesters. Their curriculum is set up online, so you can even do it at home, but you would still have to register with an institution that gives the curriculum. I could not give you the exact price because my curriculum is part of a Networking program which involves other technologies as well.
Good luck
Newby