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

[Ivo Sedlacek <[e-mail]>]

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 [phone]
[e-mail]<mailto:[e-mail]>
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>