RFC 4717, "Encapsulation Methods for Transport of Asynchronous Transfer Mode (ATM) over MPLS Networks", December 2006

Errata ID: 2920
Status: Verified
Type: Technical
Publication Format(s) : TEXT
Reported By: Alfred Hoenes
Date Reported: 2007-10-17
Verifier Name: Stewart Bryant
Date Verified: 2011-08-05

(10b)
The T bit explanation (in the lower half of page 27) contains
misleading and inappropriate wording related to Figure 4.
Figure 4 generally applies for both the proper AAL5 CPCS-SDU payload
or the case of an ATM OAM cell payload.  Furthermore, it should be
noted that Section 8.1 (which contains and explains Figure 4)
specifies the Flags field as 'reserved, should be set to 0'.
This is incompatible with the subsequent text that requires the T bit
to be set to 1 for an OAM cell.  Therefore, to avoid confusion,
the clause referencing to Figure 4 should better be deleted from
the T bit explanation.

Hence, the text,

       Bit (T) of the control word indicates whether the packet contains
       an ATM admin cell or an AAL5 payload.  If T = 1, the packet
|      contains an ATM admin cell, encapsulated according to the N-to-
|      one cell relay encapsulation, Figure 4.  If not set, the PDU
       contains an AAL5 payload.  The ability to transport an ATM cell
       in the AAL5 SDU mode is intended to provide a means of enabling
       administrative functionality over the AAL5 VCC (though it does
       not endeavor to preserve user-cell and admin-cell
       arrival/transport ordering).

should say:

       Bit (T) of the control word indicates whether the packet contains
       an ATM admin cell or an AAL5 payload.  If T = 1, the packet
|      contains an ATM admin cell.  If T = 0, the PDU contains an AAL5
       payload.  The ability to transport an ATM cell in the AAL5 SDU
       mode is intended to provide a means of enabling administrative
       functionality over the AAL5 VCC (though it does not endeavor to
       preserve user-cell and admin-cell arrival/transport ordering).

Notes:

This is section 10(b) from Erratum 999

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