Question : Firewall, switches, loadballancers etc - 101

I am doing a little presentation and need to understand what components I would come across if I was going to log into a secure "N - tier" web envirement.

This is viewed from the "user" prospective and lets say the "user" is loging into a web page for a stock trade company.

The first thing he would hit would DNS, to get the ip address of the fake company I will call "trader.com".  
Next he would hit the outside router that would protect the firewall from fragmented packets and packets that do not follow basic IP rules.
Next he would hit the firewall ( firewall 1 )
Next the "inside" router.
Next the secret second firewall that would be a different software than the first firewall.
Now we would hit switches used in pairs, also have to deal with dreded "spanning tree".
next a load ballancer
next a series of web servers
next a cluster of java jsp/Servelet server and ONE database server with it's offline standby.

There would also be a crap load of electrical equipment, ups-es and things needed for dual power.  

Can someone clear my head up on the order that this stuff would be used and the details.  

Answer : Firewall, switches, loadballancers etc - 101

Hi, please note a number of the functions may reside on the same physical piece of kit, as it's not uncommon to see something like a mirrored pair of F5 Big-IP's (http://www.f5.com/products/big-ip/) providing the:

Front End Firewall + LB + DMZ Web Layer + Back end Firewall + Back End LB's

on one (Linux based) appliance.

The mirroring provide redundancy / Capacity.

So you end up with:

Internet Cloud ->  FE Switch -> F5's ->  BE Switch -> App Server's -> BE Switch -> DB servers / Other App servers / elsewhere.