Possible correction on L2TP study notes?

tb0932

Is this correct regarding L2TP?: "The protocol being tunneled is always IP." It is in the study notes on security protocols on this site.
(The study notes are great by the way - thank you!)
Over on mcmcse.com they say the tunnel can carry NON-IP protocols such as AppleTalk, IPX/SPX because PPP supports those.
:

lordy

You are probably confusing L2TP and PPTP.

L2TP is IP only.
PPTP can tunnel other stuff like AppleTalk, IPX, etc.

tb0932

That's what I thought (after reading the study notes on this site) but mcmcse's practice tests think otherwise. Check out my link:
http://www.mcmcse.com/forums/viewtopic.php?t=7792
I have the exam this Tuesday and want to get this kind of stuff clear (and correct) before then.
Is L2TP Definitely IP only?

Webmaster

tb0932 wrote:

the tunnel can carry NON-IP protocols such as AppleTalk, IPX/SPX because PPP supports those. :

That goes for PPTP, because PPTP is an extension of PPP. L2TP is considered an extension to PPP (l2f and pptp combined) and in theory it supports all network layer protocols (like PPP) and there may be some solutions available that allow IPX, and the Microsoft client supports even Netbeui, but in general, and for the CompTIA Network+ exam, the network protocol being tunneled is always TCP/IP (which in the real world it is virtually also always).

In short:

PPTP tunnels IP, IPX, and AppleTalk over IP networks only.
L2TP tunnels IP over point-to-point networks including IP, Frame-Relay, X.25 and ATM (and is often used in conjuction with IPsec).

johnnynodough

The answer is both actually

L2TP can tunnel any routed protocol, but since you are tunneling through the internet, which is IP, the IPX/Appletalk datagram will be encapsulated for use on an IP network.

So L2TP can tunnel any routed protocol over an IP network, only when not used with IPsec.

Webmaster

-sorry to be jumping from one site to another, but I just want to clear this kind of stuff up before going into the exam...

I'm sure my good friend Jason doesn't mind.

Headhunter (mod at mcmcse.com) and Johnny are both right, L2TP, just like PPTP 'supports' the network protocols (such as IP, IPX, and AppleTalk) because those are supported by PPP.

I'm not going to say "Show me a network that tunnels IPX over l2TP", instead, I'll agree with your topic subject and change 'always' to 'usual' in the TechNotes. The updated N10-003 notes will be a bit more extensive and leave no doubt at all.

I know you won't hate me for it, but the main reason for writing these notes is to clear up doubts, not to create it. It's been a couple of years since I wrote these, but I do remember I wrote 'always' for a reason... digging...

I'm sorry if I caused any confusion.

Johan

johnnynodough

Well technically it will always be tunneling IP, they payload within may be different. Catch 22

I'm not going to say "Show me a network that tunnels IPX over l2TP"

I will ! any one who is still using IPX in a large enough scale to have the need for IPX to be wisked accoss a VPN tunnel needs to have their IT department's head checked

tb0932

You are all brilliant!
Thank you for taking so much time to clear things up for us poor sods going under the knife soon...!