[CCCure CISSP] what layers are L2TP and PPTP?

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[CCCure CISSP] what layers are L2TP and PPTP?

Ali Khalfan
From what I understand, is that L2TP is sent within a UDP header and
PPTP runs over IP.  So are these 2 considered transport layer protocols
or what they behave like which is layer 2?

What about in the DOD model, are they considered part of the link layer?

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Re: [CCCure CISSP] what layers are L2TP and PPTP?

Jim White
L2TP = "Layer Two Tunneling Protocol" (DoD and OSI model), which pretty much
answers that question.

PPTP is also considered a layer 2/3 (OSI model) implementation, and probably
resides on the Network Interface layer of the DoD model.

Much of this is very "fuzzy", lacking a clear consensus on which protocol
resides on which layer. That said, for the purposes of an exam, L2TP and
PPTP are both Layer Two (Datalink/network Interface)

Neither maps to the Transport layer, where you'll generally only find TCP
and UDP.

Jim

-----Original Message-----
From: CISSPstudy [mailto:[hidden email]] On Behalf Of Ali
Khalfan
Sent: Saturday, April 05, 2014 1:18 AM
To: [hidden email]
Subject: [CCCure CISSP] what layers are L2TP and PPTP?

From what I understand, is that L2TP is sent within a UDP header and PPTP
runs over IP.  So are these 2 considered transport layer protocols or what
they behave like which is layer 2?

What about in the DOD model, are they considered part of the link layer?

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Re: [CCCure CISSP] what layers are L2TP and PPTP?

Ali Khalfan
Thanks for the answer, James.  By networkInterface layer I'm assuming
you mean Link Layer ?  Since Network interface layer doesn't exist in
the DOD model.


James White wrote:

> L2TP = "Layer Two Tunneling Protocol" (DoD and OSI model), which pretty much
> answers that question.
>
> PPTP is also considered a layer 2/3 (OSI model) implementation, and probably
> resides on the Network Interface layer of the DoD model.
>
> Much of this is very "fuzzy", lacking a clear consensus on which protocol
> resides on which layer. That said, for the purposes of an exam, L2TP and
> PPTP are both Layer Two (Datalink/network Interface)
>
> Neither maps to the Transport layer, where you'll generally only find TCP
> and UDP.
>
> Jim
>
> -----Original Message-----
> From: CISSPstudy [mailto:[hidden email]] On Behalf Of Ali
> Khalfan
> Sent: Saturday, April 05, 2014 1:18 AM
> To: [hidden email]
> Subject: [CCCure CISSP] what layers are L2TP and PPTP?
>
> From what I understand, is that L2TP is sent within a UDP header and PPTP
> runs over IP.  So are these 2 considered transport layer protocols or what
> they behave like which is layer 2?
>
> What about in the DOD model, are they considered part of the link layer?
>
> _______________________________________________
> You can find the list archive at:
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>
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Re: [CCCure CISSP] what layers are L2TP and PPTP?

Jim White
RE: [CCCure CISSP] what layers are L2TP and PPTP?

Ali,

To my knowledge, the seven layer OSI model represent the TCP/IP network stack as :

(7)     Application

(6)     Presentation

(5)     Session

(4)     Transport

(3)     Network

(2)     Datalink

(1)     Physical

While the four layer DoD model represents the TCP/IP stack as:

(4)     Application

(3)     Transport

(2)     Internetworking

(1)     Network Interface (Link)

In that context, The "Network Interface" (AKA "Datalink Layer" and "Physical Layer" in the OSI Model and the "Link Layer" in the DoD model) represent the same logical location, and would be where the L2TP and PPTP protocols reside.

Popular nomenclature often substitutes "Network Interface Layer" for "Link Layer", which is where our inconsistency arises.

Note that my experience with the (ISC)2 annotation suggests that they will embrace the more archaic "Network Interface" over the "Link" designation for the lowest layer.

Jim

-----Original Message-----
From: CISSPstudy [[hidden email]] On Behalf Of Ali Khalfan
Sent: Saturday, April 05, 2014 4:26 AM
To: [hidden email]
Subject: Re: [CCCure CISSP] what layers are L2TP and PPTP?

Thanks for the answer, James.  By networkInterface layer I'm assuming you mean Link Layer ?  Since Network interface layer doesn't exist in the DOD model.


James White wrote:

> L2TP = "Layer Two Tunneling Protocol" (DoD and OSI model), which

> pretty much answers that question.

>

> PPTP is also considered a layer 2/3 (OSI model) implementation, and

> probably resides on the Network Interface layer of the DoD model.

>

> Much of this is very "fuzzy", lacking a clear consensus on which

> protocol resides on which layer. That said, for the purposes of an

> exam, L2TP and PPTP are both Layer Two (Datalink/network Interface)

>

> Neither maps to the Transport layer, where you'll generally only find

> TCP and UDP.

>

> Jim

>

> -----Original Message-----

> From: CISSPstudy [[hidden email]] On Behalf Of

> Ali Khalfan

> Sent: Saturday, April 05, 2014 1:18 AM

> To: [hidden email]

> Subject: [CCCure CISSP] what layers are L2TP and PPTP?

>

> From what I understand, is that L2TP is sent within a UDP header and

> PPTP runs over IP.  So are these 2 considered transport layer

> protocols or what they behave like which is layer 2?

>

> What about in the DOD model, are they considered part of the link layer?

>

> _______________________________________________

> You can find the list archive at:

> http://cissp-study.3965.n7.nabble.com/

>

> CISSPstudy mailing list

> [hidden email]

>

> To UNSUBSCRIBE, SUBSCRIBE, or MANAGE your accout visit the link below:

> http://cccure.org/mailman/listinfo/cisspstudy_cccure.org

>

>

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> This email is free from viruses and malware because avast! Antivirus protection is active.

> http://www.avast.com

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>

> _______________________________________________

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> http://cissp-study.3965.n7.nabble.com/

>

> CISSPstudy mailing list

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>

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>

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