Subject: Re: [L2tpext] [PWE3] HDLCPW L2TPv3 (RFC 4349): Transport of LAPD frames

From: Carlos Pignataro <[email-masked]>
Date: Wed, 22 Jul 2009 10:44:08 -0400

[moving to <[email-masked]> since the reference of RFC4349]

Javier,

As Stewart answered, LAPD would look like any other HDLC packet to an
HDLC PW. All the data (address (SAPI/TEI), control, etc) is opaque to
the HDLC PW; flags and trailing FCS are stripped, and there rest is
transported.

Thanks,

-- Carlos.

On 7/21/2009 12:38 PM, Javi wrote:
> Stewart Bryant escribió:
>> I am not sure how much LAPD there is still in existence.
> There are many reasons to support LAPD. For example, the accommodation 
> of legacy PSTN/ISDN terminals and/or interworking with the PSTN/ISDN
> is an important consideration with respect to NGN deployment (ITU-T Y.2012)
>> LAPD would look like any other HDLC packet to an HDLC PW.
> However, LAPD is not mentioned in RFC 4349 neither other document about 
> HDLCPW.
> Does HDLCPW support these extensions of LAPD beyond HDLC?
> 
> Javier Muñoz
>>
>> Stewart
>>
>>
>>
>> Javi wrote:
>>> Chapter 4.1: Data Packet Encapsulation
>>>
>>>    Since all packets are passed in a largely transparent manner over the
>>>    HDLCPW, any protocol that has HDLC-like framing may utilize the
>>>    HDLCPW mode, including PPP, Frame-Relay ("port to port" Frame-Relay
>>>    transport), X.25 (LAPB), etc.
>>>
>>>
>>> I have read many times: "LAPD (derived from LAPB) is a subset of the 
>>> HDLC structure, although it has extensions beyond HDLC"
>>>
>>>
>>> Which are these extensions?. In any case, may does HDLCPW mode be 
>>> used to transport LAPD frames?. Why yes or not?
>>>
>>>
>>> Thanks
>>>
>>> Javier Muñoz
>>>
>>>
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> 
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