Difference Between Ethernet WAN and Ethernet ports.

So i was in the process of buying a cisco router today and im looking for one to get connected to my VDSL modem, i was looking for one with an ethernet WAN port. Then i got thinking and was wondering why i actually need an ethernet WAN port why can i use just a normal LAN port?

This might be a pretty novice question, but can someone just point me in the right direction, i mean what actually changes? The physical side is the same (well atleast the cable is), so how do the ports actually differ??

How do the protocols play a part in the different comunication? Bearing in mind the router will just connect to a modem that will change the signal,

Thanks in advance.

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Comments

Christopher Dobkowski

I think this might help you

https://supportforums.cisco.com/thread/2131926

JustFred

I think this might help.

Cisco WAN Interface Cards - Products & Services - Cisco Systems

DANMOH009

So they say you cant apply IP address's to a normal LAN port, but you can, so this is why im getting confused i understand one is set for L2 and WANs for L3. I just dont really understand what stops the port from receiving L3 information.

I think i desperately need a lab to continue and start messing around with things, GNS and PT just cant help with some things.

Somnipotent

DANMOH009 wrote: »

So they say you cant apply IP address's to a normal LAN port, but you can, so this is why im getting confused i understand one is set for L2 and WANs for L3. I just dont really understand what stops the port from receiving L3 information.

I think i desperately need a lab to continue and start messing around with things, GNS and PT just cant help with some things.

Of course you can throw an IP address on an Ethernet interface. And any port built in your box should do just fine. I think what's confusing you is the difference between a switchport and a routed port, which does not matter in your case. For example, if you were to get a 1841, it comes with two fastE ports on board. Either of those ports will work just fine. Now if it were a MLS or L3 switch, like a 3560, all ports are native switch ports, to make it routable and allow it to take on an IP address, you'd have to issue a "no switchport" command. Again, this doesn't apply to you.

WAN interface cards are typically for direct T1, serial, ISDN, etc. You don't need that. Your DSL modem already connects you to the "WAN", you just need to plug the RJ45 from your modem to one of your fastE ports, configure the port for dhcp (or assign your own IP address) and you're good.

DANMOH009

Ahhhh so it would work!!!

Thanks a million this really confused me!!

If only i knew this 24 hours ago, could of picked up an 837 (i know its not the greatest) for £10.00 off ebay