Subject: [MMUSIC] Comments to draft-ietf-mmusic-media-path-middleboxes

From: Ivo Sedlacek <[email-masked]>
Date: Thu, 30 May 2013 14:11:27 +0000

Hello,

Comments to draft-ietf-mmusic-media-path-middleboxes-06:

Comment 1:

ISSUE:

http://tools.ietf.org/html/draft-ietf-mmusic-media-path-middleboxes-06 states:
-------------------

3.  Architecture

   Figure 1 shows the architecture that is being considered in this

   document with respect to firewall and NAT traversal using media

   relaying.  The timing and directionality with which media packets are

   allowed to traverse a particular edge device is the subject of this

   investigation.  The MIDCOM agent thereby pushes policy rules to the

   middlebox that allow or deny certain flows to >>bypass<<.  Additionally,

   in case of media relaying it is important for the MIDCOM agent to

   adjust the signaling messages.

                     SIP     +-----------------+     SIP

         +-----+  Signaling  |     SIP ALG     |  Signaling  +-----+

         | UAC |<----------->+-----------------+<----------->| UAS |

         +-----+             |   MIDCOM Agent  |             +-----+

            ^                +-----------------+                ^

            |                         ^                         |

            |          Policy rule(s) | and NAT bindings        |

            |                         v                         |

            |      Media       +-------------+       Media      |

            +----------------->|  Middlebox  |<-----------------+

                               +-------------+

                Figure 1: Analysed Firewalling Architecture

   The aspects of packet filtering are described in Section 4 whereas

   NAT traversal is illustrated in Section 5.
-------------------

The word "bypass" does not seem to be correct.

"bypass" is defined by http://dictionary.cambridge.org/ as: "to avoid something by going around it" or " to ignore a rule or official authority".

However, the figure 1 shows media of the flows passing through/via the middlebox, not around the middlebox.

PROPOSAL:
-------------------

3.  Architecture

   Figure 1 shows the architecture that is being considered in this

   document with respect to firewall and NAT traversal using media

   relaying.  The timing and directionality with which media packets are

   allowed to traverse a particular edge device is the subject of this

   investigation.  The MIDCOM agent thereby pushes policy rules to the

   middlebox that allow or deny certain flows to >>pass through<<.  Additionally,

   in case of media relaying it is important for the MIDCOM agent to

   adjust the signaling messages.

                     SIP     +-----------------+     SIP

         +-----+  Signaling  |     SIP ALG     |  Signaling  +-----+

         | UAC |<----------->+-----------------+<----------->| UAS |

         +-----+             |   MIDCOM Agent  |             +-----+

            ^                +-----------------+                ^

            |                         ^                         |

            |          Policy rule(s) | and NAT bindings        |

            |                         v                         |

            |      Media       +-------------+       Media      |

            +----------------->|  Middlebox  |<-----------------+

                               +-------------+

                Figure 1: Analysed Firewalling Architecture

   The aspects of packet filtering are described in Section 4 whereas

   NAT traversal is illustrated in Section 5.
-------------------

Comment 2:

ISSUE:

http://tools.ietf.org/html/draft-ietf-mmusic-media-path-middleboxes-06 states:
-------------------
   REC #4:  If signaling on the media path is required before media can
      flow, the >>answer<< should send the SDP answer as soon as possible,
      for example within a provisional SIP response, to allow the media
      path signaling to bypass middleboxes and therefore to avoid
      clipping.
-------------------
I believe there is an error.

PROPOSAL:
-------------------
   REC #4:  If signaling on the media path is required before media can
      flow, the >>answerer<< should send the SDP answer as soon as possible,
      for example within a provisional SIP response, to allow the media
      path signaling to bypass middleboxes and therefore to avoid
      clipping.
-------------------

Comment 3:

ISSUE:

http://tools.ietf.org/html/draft-ietf-mmusic-media-path-middleboxes-06 states:
-------------------
   REC #4:  If signaling on the media path is required before media can
      flow, the answer should send the SDP answer as soon as possible,
      for example within a provisional SIP response, to allow the media
      path signaling to >>bypass<< middleboxes and therefore to avoid
      clipping.
-------------------
Same issue as in Comment 1.

PROPOSAL:
-------------------
   REC #4:  If signaling on the media path is required before media can
      flow, the answer should send the SDP answer as soon as possible,
      for example within a provisional SIP response, to allow the media
      path signaling to >>pass through<< middleboxes and therefore to avoid
      clipping.
-------------------

Kind regards

Ivo Sedlacek

Ericsson
Mobile +420 608 234 709
[email-masked]<mailto:[email-masked]>
www.ericsson.com<http://www.ericsson.com>

This Communication is Confidential. We only send and receive email on the basis of the terms set out at www.ericsson.com/email_disclaimer<http://www.ericsson.com/email_disclaimer>

---

From: Gonzalo Salgueiro <[email-masked]>
Date: Thu, 30 May 2013 14:02:58 -0400

Thanks, Ivo.  I have posted a new version addressing your and Bruno's comments.

Thanks,

Gonzalo

On May 30, 2013, at 10:11 AM, Ivo Sedlacek <[email-masked]> wrote:

> [email-masked]
> www.ericsson.com
>  
> This Communication is Confidential. We only send and receive email on the basis of the terms set out at www.ericsson.com/email_disclaimer

---

From: Ivo Sedlacek <[email-masked]>
Date: Fri, 31 May 2013 09:49:29 +0000

Thank you for covering my comments in draft-ietf-mmusic-media-path-middleboxes-07.

Kind regards

Ivo Sedlacek

-----Original Message-----
From: Gonzalo Salgueiro [mailto:[email-masked]] 
Sent: 30. května 2013 20:03
To: Ivo Sedlacek
Cc: [email-masked]; [email-masked]; [email-masked]
Subject: Re: Comments to draft-ietf-mmusic-media-path-middleboxes

Thanks,

Gonzalo

---

From: "Hannes Tschofenig" <[email-masked]>
Date: Fri, 31 May 2013 13:31:03 +0200 (CEST)

Thanks for the careful reading of the document and for providing actionable feedback, Ivo.

And thanks to Gonzalo for reacting so quickly with a new draft update.

Ciao

Hannes

Gesendet: Freitag, 31. Mai 2013 um 11:49 Uhr

Von: "Ivo Sedlacek" <[email-masked]>

An: "Gonzalo Salgueiro" <[email-masked]>

Cc: "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>

Betreff: RE: Comments to draft-ietf-mmusic-media-path-middleboxes

Kind regards

Ivo Sedlacek

-----Original Message-----

To: Ivo Sedlacek

Thanks,

Gonzalo