Subject: [rohc] puzzle aboout respond to lost feedback links

From: "LI_JING" <[email-masked]>
Date: Thu, 3 Nov 2005 15:51:26 +0800

hi, ROHCers,

            As 8.8 in <The RFC 3095 Implementer's Guide> state,

  "  8.8  How to respond to lost feedback links

  One potential issue that might have to be considered, depending on
   link technology, is whether feedback links might get lost, and in
   such cases how this is handled. When the compressor is notified that
   the feedback channel is down, the compressor must be able to handle
   it by restarting compression with creating a new context. Creating a
   new context also implies to use a new CID value.
 
   Generally, feedback links are not expected to disappear when once
   present, but it should be noted that this might be the case for
   certain link technologies.."
　　　　　　　　　　　　　
　        Why here suggest creating a new context to compress instead of
using old context,which back its current mode to U mode ? 
    
           U mode is just designed for compression without feedback link.Here
I think, just a proper application for U mode.

         How about your ideas ?       　
　　　　　　　　　　　　　
　　　　　　　　　　　　　　　　
BR
LI JING  
TEL: (+86)029-87916666-6075
Mail: [email-masked]
****************************************************************
This e-mail and its attachments contain confidential information 
from DATANG MOBILE, which is intended only for the person or entity
whose address is listed above. Any use of the information contained 
herein in any way (including, but not limited to, total or partial
 disclosure, reproduction, or dissemination) by persons other than 
the intended recipient(s) is prohibited. If you receive this e-mail 
in error, please notify the sender by phone or email immediately 
and delete it!  Thank you.
*****************************************************************

　　　　　　　　
　　　　　　　　　　　　　
　　　　　　　　　　　　　　　　
BR
LI JING  %DATE
 
TEL: (+86)029-87916666-6075
Mail: [email-masked]
****************************************************************
This e-mail and its attachments contain confidential information 
from DATANG MOBILE, which is intended only for the person or entity
whose address is listed above. Any use of the information contained 
herein in any way (including, but not limited to, total or partial
 disclosure, reproduction, or dissemination) by persons other than 
the intended recipient(s) is prohibited. If you receive this e-mail 
in error, please notify the sender by phone or email immediately 
and delete it!  Thank you.
*****************************************************************
_______________________________________________
Rohc mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/rohc

---

From: "Ghyslain Pelletier (LU/EAB)" <[email-masked]>
Date: Thu, 3 Nov 2005 13:23:55 +0100

> A mode switch back to U-mode must be initiated by the 
> decompressor, which can't be done if the link disappears. One 
> can thus not continue with the same context but must instead 
> re-initialize compression with a new context, starting (as 
> always) in U-mode.

This is to avoid that packet types be misinterpreted in case the flow
was operating using R-mode (some packet types indicators are common
between U/O-mode and R-mode).

However, I think this section is poorly written. I would suggest the
following text as replacement:

8.8. How to respond to lost feedback links?

   Althought this is neither desirable or expected, it may happen that
   a link used to carry feedback between two associated instances
   become unavailable. If the compressor can be notified of such
   event, the most suitable response in such case is for the
   compressor to restart compression for each flow going over the ROHC
   channel, except for flows that are operating in U/O-mode or flows
   using a CID associated with the uncompressed profile (profile
   0x0000). When restarting compression, the compressor SHOULD use a
   different CID for each flow being restarted; this is useful to
   avoid that packet types for which both U/O-mode and R-mode share
   the same type identifier gets misinterpreted when restarting the
   flow in U-mode.

First, I'd like to know if the suggested text above captures the correct
understanding that the text in the implementer's guide is trying to
achieve. If not, then it means that I also fail to understand the text
in the draft. Second, I'd like to know if this text is clearer so that
it should replace section 8.8.

/Ghyslain

> 
> /L-E
> 
> -----Original Message-----
> From: "LI_JING" <[email-masked]>
> To: "rohc" <[email-masked]>
> Date: Thu, 3 Nov 2005 15:51:26 +0800
> Subject: [rohc] puzzle aboout respond to lost feedback links
> 
> hi, ROHCers,
> 
>         Why here suggest creating a new context to compress 
> instead of using old context,which back its current mode to U mode ? 
>     
>            U mode is just designed for compression without 
> feedback link.Here I think, just a proper application for U mode.
> 
>          How about your ideas ?       
> 
> 
> BR
> LI JING
> This e-mail and its attachments contain confidential 
> information from DATANG MOBILE, which is intended only for 
> the person or entity whose address is listed above. Any use 
> of the information contained herein in any way (including, 
> but not limited to, total or partial  disclosure, 
> reproduction, or dissemination) by persons other than the 
> intended recipient(s) is prohibited. If you receive this 
> e-mail in error, please notify the sender by phone or email 
> immediately and delete it!  Thank you.
> This e-mail and its attachments contain confidential 
> information from DATANG MOBILE, which is intended only for 
> the person or entity whose address is listed above. Any use 
> of the information contained herein in any way (including, 
> but not limited to, total or partial  disclosure, 
> reproduction, or dissemination) by persons other than the 
> intended recipient(s) is prohibited. If you receive this 
> e-mail in error, please notify the sender by phone or email 
> immediately and delete it!  Thank you.

---

From: "Lars-Erik Jonsson (LU/EAB)" <[email-masked]>
Date: Fri, 11 Nov 2005 13:07:14 +0100

Yes, I think this text captures what the current text is mainly
trying to capture, and maybe it does it better. I can replace
the current text with this proposed variant.

Anyone disagrees? Otherwise, I will do this in the next update.

/L-E

> From: [email-masked] [mailto:[email-masked]]On Behalf Of
> Ghyslain Pelletier (LU/EAB)
> Sent: den 3 november 2005 13:24
> To: Lars-Erik Jonsson; [email-masked]
> Cc: [email-masked]
> Subject: RE: [rohc] puzzle aboout respond to lost feedback links
> 
>