Subject: PPP Over ATM AAL5

From: [email-masked] (Terry Buckley)
Date: Mon, 22 Jun 1998 13:24:18 -0500

The draft does a good job at addressing the header questions and the other ATM
related areas. While considering implementation the following came up.

Should the draft have the following statments added ?

1. No ACCM escaping of any data is required.

2. CRC is not required in the PPP packet, the AAL5 CRC guarantees data
integrity.

3. The CPCS-SDU size for PPP over ATM is 1536. Or state what the MTU really is
in the real world...

Thanks,

Terry

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Terry Buckley                           [email-masked]
Efficient Networks, Inc.		"You can never be too rich, too thin,
(972) 991-3884                             or have too much bandwidth"
(972) 991-3887(fax)                    	http://www.efficient.com

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From: [email-masked] (luna3!gmg)
Date: Mon, 22 Jun 1998 16:18:38 -0400

Hi Terry,

> related areas.

thank you :-)

> While considering implementation the following came up.
> 

Section 9 in the ID discusses LCP option negotiation, and it states
that ACCM must not be requested, and it must be rejected if it is requested.
Within RFC1662, section 7.1 specifies that the default ACCM value is 0.

> 2. CRC is not required in the PPP packet, the AAL5 CRC guarantees data

Section 1 in the ID points out that the virtual connection will
include error detection but not error correction.

> 3. The CPCS-SDU size for PPP over ATM is 1536. Or state what the MTU really is

Section 9 only requires that the MRU must not be negotiated to a larger
size than the maximum CPCS-SDU size in the associated direction. Both the
max CPCS-SDU length and MRU value are implementation dependent and often
can be set under admin control.

Hope this clarifies things...

	George