Re: [ippm] On progressing draft-mirsky-ippm-stamp-option-tlv

[Greg Mirsky <[e-mail]>]

Hi Tianran,
thank you for your interest in the proposal on the optional extensions of
STAMP. Please find my answers in-line below tagged GIM>>.

Regards,
Greg

On Mon, Jun 24, 2019 at 1:59 AM Tianran Zhou <[e-mail]> wrote:

> Hi Greg,
>
>
>
> Several clarification questions after reading this draft.
>
>
>
> 1. Maybe wrt to section 4. Could you please explicitly describe the
> mechanism to detect the existence of TLVs, in addition to the fixed message
> part?
>
GIM>> Since the length of the base STAMP packet, and the mode,
unauthenticated or authenticated, are known, the receiver of a STAMP packet
can determine if there are any TLV by comparing the length of the base
STAMP packet with the value of the Total length field of IP header.

>
>
> 2. Could you please describe the use case for each TLV you proposed?
> Especially the “Location TLV” and the “Class of Service TLV”. I can
> hardly understand why these two are useful, and how to use them to do
> measurement/collection.
>
GIM>> We'll expand the informational text for TLVs. For the Location TLV,
the use is described in the draft as follows:

   The Location TLV MAY be used to determine the last-hop addressing for
   STAMP packets including source and destination IP addresses as well
   as the MAC address of the last-hop router.  Last-hop MAC address MAY
   be monitored by the Session-Sender whether there has been a path
   switch on the last hop, closest to the Session-Reflector.  The IP
   addresses and UDP port will indicate if there is a NAT router on the
   path, and allows the Session-Sender to identify the IP address of the
   Session-Reflector behind the NAT, detect changes in the NAT mapping
   that could cause sending the STAMP packets to the wrong Session-
   Reflector.

The use case of the Class of Service TLV is the same as of RFC 7750
<https://datatracker.ietf.org/doc/rfc7750/> and
draft-bailmir-ippm-twamp-dscp-ctrl-mon
<https://www.ietf.org/archive/id/draft-bailmir-ippm-twamp-dscp-ctrl-mon-02.txt>
.

>
>
> Thanks,
>
> Tianran
>
>
>
> *From:* ippm [mailto:[e-mail]] *On Behalf Of *Greg Mirsky
> *Sent:* Thursday, June 20, 2019 3:06 PM
> *To:* IPPM Chairs <[e-mail]>; IETF IPPM WG <[e-mail]>
> *Cc:* [e-mail]
> *Subject:* [ippm] On progressing draft-mirsky-ippm-stamp-option-tlv
>
>
>
> Dear Chairs, et al.,
>
> authors of draft-mirsky-ippm-stamp-option-tlv believe that it is stable
> and detailed enough to ask for your consideration to start the WG Adoption
> Poll.
>
>
>
> Regards,
>
> Greg
>