thank you very much Michael.
I still think that X.25 is layer 3 but you are right correcting
about LAPB and LAPD, they are only layer 2.
-----Original Message-----
From: Michael Williams [mailto:GoldChain@xxxxxxxxx]
Sent: 02 May 2002 17:15
To: associate@xxxxxxxxxxxxxx
Subject: RE: about WAN protocols and its layer assignments [1:9134]
I'm going to qualify my following answers with "I would need to check on the
web, etc to make sure, but this is what I'm thinking is correct off the top
of my head".... =)
ALot of these protocols are really multilayered and it's hard to say that
it's only Layer 2 or Layer 1, etc.....
Marcial Rosales Garcia wrote:
> X.25 - layer 3
X.25 is a layer 2 encapsulation, and uses X.121 addressing for Layer 2
communications. Don't know if X.25 specifies L1 stuff, but wouldn't
surprise me.
> ISDN - layer 3 (but also layer2 and layer1)
ISDN does have a layer 3 component (Q.931) but also Layer 2 components
(Q.921) and layer 1 specifications
> PPP - layer 2
I agree with the other post on this one.... PPP is L2 only.
> FR - layer 2 (but also layer1)
FR is is both a layer 2 and layer 1 thing....
> ATM - layer 2 (but also layer1)
ATM actually has 3 layers that fit into to Layer 1 and Layer 2 of OSI.
> HDLC - layer 2 (but also layer1)
HDLC also is a Layer 2 and Layer 1 thing
> LAPB same
> LAPD same (only for ISDN)
I think LAPB and LAPB are only Layer 2 things.........
THat's my take on it...... =)
Mike W.
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