A capital R in this table means 'header field may only appear in requests'. 
Page 160 RFC 3261.
Regards
Steve


-----Original Message-----
From: Prithvi [mailto:[EMAIL PROTECTED]
Sent: 02 March 2007 12:36
To: Stephen Paterson
Cc: Satyendra Tiwari; [email protected]
Subject: Re: [Sip-implementors] Max-Forward Header


Hi Stephen

    Please check the table listed in sec 20.1 which says
      Max-Forwards            R      amr   m   m   m   m   m   m
and

m: The header field is mandatory.



Example:

      Header field          where   proxy ACK BYE CAN INV OPT REG
      ___________________________________________________________
      Accept                  R            -   o   -   o   m*  o
      Accept                 2xx           -   -   -   o   m*  o
      Accept                 415           -   c   -   c   c   c
      Accept-Encoding         R            -   o   -   o   o   o
      Accept-Encoding        2xx           -   -   -   o   m*  o
      Accept-Encoding        415           -   c   -   c   c   c
      Accept-Language         R            -   o   -   o   o   o
      Accept-Language        2xx           -   -   -   o   m*  o
      Accept-Language        415           -   c   -   c   c   c
      Alert-Info              R      ar    -   -   -   o   -   -
      Alert-Info             180     ar    -   -   -   o   -   -
      Allow                   R            -   o   -   o   o   o
      Allow                  2xx           -   o   -   m*  m*  o
      Allow                   r            -   o   -   o   o   o
      Allow                  405           -   m   -   m   m   m
      Authentication-Info    2xx           -   o   -   o   o   o
      Authorization           R            o   o   o   o   o   o
      Call-ID                 c       r    m   m   m   m   m   m
      Call-Info                      ar    -   -   -   o   o   o
      Contact                 R            o   -   -   m   o   o
      Contact                1xx           -   -   -   o   -   -
      Contact                2xx           -   -   -   m   o   o
      Contact                3xx      d    -   o   -   o   o   o
      Contact                485           -   o   -   o   o   o
      Content-Disposition                  o   o   -   o   o   o
      Content-Encoding                     o   o   -   o   o   o
      Content-Language                     o   o   -   o   o   o
      Content-Length                 ar    t   t   t   t   t   t
      Content-Type                         *   *   -   *   *   *
      CSeq                    c       r    m   m   m   m   m   m
      Date                            a    o   o   o   o   o   o
      Error-Info           300-699    a    -   o   o   o   o   o
      Expires                              -   -   -   o   -   o
      From                    c       r    m   m   m   m   m   m
      In-Reply-To             R            -   -   -   o   -   -
      Max-Forwards            R      amr   m   m   m   m   m   m
      Min-Expires            423           -   -   -   -   -   m
      MIME-Version                         o   o   -   o   o   o
      Organization                   ar    -   -   -   o   o   o

             Table 2: Summary of header fields, A--O






Rosenberg, et. al.          Standards Track                   [Page 162]

RFC 3261            SIP: Session Initiation Protocol           June 2002


   Header field              where       proxy ACK BYE CAN INV OPT REG
   ___________________________________________________________________
   Priority                    R          ar    -   -   -   o   -   -
   Proxy-Authenticate         407         ar    -   m   -   m   m   m
   Proxy-Authenticate         401         ar    -   o   o   o   o   o
   Proxy-Authorization         R          dr    o   o   -   o   o   o
   Proxy-Require               R          ar    -   o   -   o   o   o
   Record-Route                R          ar    o   o   o   o   o   -
   Record-Route             2xx,18x       mr    -   o   o   o   o   -
   Reply-To                                     -   -   -   o   -   -
   Require                                ar    -   c   -   c   c   c
   Retry-After          404,413,480,486         -   o   o   o   o   o
                            500,503             -   o   o   o   o   o
                            600,603             -   o   o   o   o   o
   Route                       R          adr   c   c   c   c   c   c
   Server                      r                -   o   o   o   o   o
   Subject                     R                -   -   -   o   -   -
   Supported                   R                -   o   o   m*  o   o
   Supported                  2xx               -   o   o   m*  m*  o
   Timestamp                                    o   o   o   o   o   o
   To                        c(1)          r    m   m   m   m   m   m
   Unsupported                420               -   m   -   m   m   m
   User-Agent                                   o   o   o   o   o   o
   Via                         R          amr   m   m   m   m   m   m
   Via                        rc          dr    m   m   m   m   m   m
   Warning                     r                -   o   o   o   o   o
   WWW-Authenticate           401         ar    -   m   -   m   m   m
   WWW-Authenticate           407         ar    -   o   -   o   o   o

regards
Prithvi


Stephen Paterson wrote:
> Hi Prithvi,
>
> The passage you quote states that, 'all of these header fields are mandatory 
> in all SIP requests'. That is, not all SIP messages, only requests. They are 
> not necessarily mandatory for responses (although some are). Tables 2 & 3 
> (pages 162 & 163 RFC 3261) shows that Max-Forwards is only relevant for 
> requests.
>
> Regards
>
> Steve
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] Behalf Of Prithvi
> Sent: 02 March 2007 05:43
> To: Satyendra Tiwari
> Cc: [email protected]
> Subject: Re: [Sip-implementors] Max-Forward Header
>
>
> Hi Satya
>      Maxforward is mandatory in all SIP messages see 8.1.1 for more info
>
> 8.1.1 Generating the Request A valid SIP request formulated by a UAC 
> MUST, at a minimum, contain the following header fields: To, From, CSeq, 
> Call-ID, Max-Forwards, and Via; all of these header fields are mandatory 
> in all SIP requests. These six header fields are the fundamental 
> building blocks of a SIP message, as they jointly provide for most of 
> the critical message routing services including the addressing of 
> messages, the routing of responses, limiting message propagation, 
> ordering of messages, and the unique identification of transactions. 
> These header fields are in addition to the mandatory request line, which 
> contains the method, Request-URI, and SIP version.
>
> Regards
> Prithvi
>
> Satyendra Tiwari wrote:
>   
>> Hello,
>>
>> Is Max-Forward header mandatory in SIP responces?
>> If optional then why?
>>
>>
>>  
>>  
>>
>> Thanks And Regards,
>> Satyendra Tiwari
>> Alcatel-Lucent
>> _______________________________________________
>> Sip-implementors mailing list
>> [email protected]
>> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
>>
>>   
>>     
>
> _______________________________________________
> Sip-implementors mailing list
> [email protected]
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>
>   


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