Subject: RE: [rohc] Partial_State_ID calculation at compressor End

From: "Lajos Zaccomer (IJ/ETH)" <[email-masked]>
Date: Wed, 12 May 2004 09:50:23 +0200

Hi,
 
As far as I know, using a reliable transport makes feedbacks unnecessary. In such a case, it is not the feedback you need to decide if the requested save state operation has been performed but the advertisement of SMS > 0 (as Suman mentioned it might be 0).
In the example, the first message might advertise SMS > 0, which I believe is enough to think that the BYTECODE was successfully saved, so there is no need to repeat it in the 180 Ringing.
Note that the feedback in itself is not enough to know if the save state was indeed all right, because there might be some kind of state database error or lack of memory in state handler, while the requested feedback is still sent back (indicating only that the application accepted the decompressed message).
 
BR/Zacco

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of suman
Sent: Wednesday, May 12, 2004 8:52 AM
To: [email-masked]; [email-masked]
Subject: Re: [rohc] Partial_State_ID calculation at compressor End

In your example, the 180 ringing will always carry the bytecode in case of both UDP and TCP.
This is because the other endpoint could be stateless with sms = 0. 
Without receiving feedback from the peer endpoint, it cannot be assumed that the states are saved.
 
thanks
suman

----- Original Message ----- 
From: [email-masked] <mailto:[email-masked]>  
To: [email-masked] <mailto:[email-masked]>  
Sent: Wednesday, May 12, 2004 10:19 AM
Subject: [rohc] Partial_State_ID calculation at compressor End

RFC 3321 says 

"The compressor must only use states   that are established at the remote decompressor, otherwise a decompression failure will occur.  For this reason,  acknowledgements are necessary, at least for unreliable transport." 

My case is as follows : 

1. EP1 sends compressed INVITE message with decompression BYTECODE to EP2. 
2. EP2 saves state EP2_S1. 
2. EP2 sends compressed 100 Trying  message with decompression  BYTECODE to EP1. 
3. EP1 saves state EP1_S1. 
4. Now when EP2 wants to send 180 ringing and it has not go the ack for state EP1_S1. 

My question is in case of TCP, can the EP2 send the partial_state_Id instead of uploading BYTECODE again when it sends 180 Ringing. 

If so how the partial_state_id will be calculated at EP2 compressor End.

---

From: [email-masked]
Date: Wed, 12 May 2004 13:43:49 +0530

Hi,

A couple of points

1. If you don't send the feedback in the case of TCP , how do you know the
partial state id of the saved state so that u can send it in the next
message you send ? the partial state id is calculated when the UDVM
executes at the remote end.

2. I believe,  if the state save fails due to some reason, the requested
feedback should not be sent back at all by the receiving endpoint.

regds,
suprabhat

             "Lajos Zaccomer                                               
             (IJ/ETH)"                                                     
             <lajos.zaccomer@e                                          To 
             ricsson.com>              "'suman'" <[email-masked]>,      
             Sent by:                  [email-masked], [email-masked]    
             [email-masked]                                          cc 
             rg                                                            
                                                                   Subject 
                                       RE: [rohc] Partial_State_ID         
             05/12/04 01:20 PM         calculation at compressor End       

                                                                           

Hi,

As far as I know, using a reliable transport makes feedbacks unnecessary.
In such a case, it is not the feedback you need to decide if the requested
save state operation has been performed but the advertisement of SMS > 0
(as Suman mentioned it might be 0).
In the example, the first message might advertise SMS > 0, which I believe
is enough to think that the BYTECODE was successfully saved, so there is no
need to repeat it in the 180 Ringing.
Note that the feedback in itself is not enough to know if the save state
was indeed all right, because there might be some kind of state database
error or lack of memory in state handler, while the requested feedback is
still sent back (indicating only that the application accepted the
decompressed message).

BR/Zacco
      -----Original Message-----
      From: [email-masked] [mailto:[email-masked]]On Behalf Of
      suman
      Sent: Wednesday, May 12, 2004 8:52 AM
      To: [email-masked]; [email-masked]
      Subject: Re: [rohc] Partial_State_ID calculation at compressor End

      In your example, the 180 ringing will always carry the bytecode in
      case of both UDP and TCP.
      This is because the other endpoint could be stateless with sms = 0.
      Without receiving feedback from the peer endpoint, it cannot be
      assumed that the states are saved.

      thanks
      suman
       ----- Original Message -----
       From: [email-masked]
       To: [email-masked]
       Sent: Wednesday, May 12, 2004 10:19 AM
       Subject: [rohc] Partial_State_ID calculation at compressor End

       RFC 3321 says

       "The compressor must only use states   that are established at the
       remote decompressor, otherwise a decompression failure will occur.
       For this reason,  acknowledgements are necessary, at least for
       unreliable transport."

       My case is as follows :

       1. EP1 sends compressed INVITE message with decompression BYTECODE
       to EP2.
       2. EP2 saves state EP2_S1.
       2. EP2 sends compressed 100 Trying  message with decompression
       BYTECODE to EP1.
       3. EP1 saves state EP1_S1.
       4. Now when EP2 wants to send 180 ringing and it has not go the ack
       for state EP1_S1.

       My question is in case of TCP, can the EP2 send the partial_state_Id
       instead of uploading BYTECODE again when it sends 180 Ringing.

       If so how the partial_state_id will be calculated at EP2 compressor
       End.

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