Subject: [AVT] Q about draft-ietf-avt-rtp-new-12

From: "Oren Peleg" <[email-masked]>
Date: Tue, 17 Jun 2003 13:03:00 +0300

In the draft-ietf-avt-rtp-new-12 it is mentioned that the RTCP packet MUST end on a 32-bit boundary. At the RTCP Padding section, it is mentioned that the padding is done octet based - length value is at  the last padding octet: 

"If the padding bit is set, this individual RTCP packet
             contains some additional padding octets at the end which
             are not part of the control information but are included in
             the length field.  The last octet of the padding is a count
             of how many padding octets should be ignored, including
             itself (it will be a multiple of four)."

As I understand it, the Padding MUST be 32-bit aligned. Is my assumption correct? if it is, shouldn't it be mentioned at the Padding part? If this will be misunderstood, it could cause reading of a garbage octet as the padding length ...

Regards, 

Oren Peleg

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---

From: Stephen Casner <[email-masked]>
Date: Tue, 17 Jun 2003 09:45:48 -0700 (PDT)

On Tue, 17 Jun 2003, Oren Peleg wrote:

> In the draft-ietf-avt-rtp-new-12 it is mentioned that the RTCP
> packet MUST end on a 32-bit boundary. At the RTCP Padding section,
> it is mentioned that the padding is done octet based - length value
> is at the last padding octet:
>
> As I understand it, the Padding MUST be 32-bit aligned. Is my
> assumption correct? if it is, shouldn't it be mentioned at the
> Padding part? If this will be misunderstood, it could cause reading
> of a garbage octet as the padding length ...

This text seems clear to me.  The padding must fit within the length
field, which is in units of 32-bit words; it is appended to the
contents of an RTCP packet, which must end on a 32-bit boundary for
all packet types; and the padding count is a multiple of four.

What construction did you envision that complies with those
requirements and is not 32-bit aligned?

                                                        -- Steve

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