RFC3261: SIP:20.16 CSeq

20.16 CSeq

   A CSeq header field in a request contains a single decimal sequence number and the request method.  The sequence number MUST be expressible as a 32-bit unsigned integer.  The method part of CSeq is case-sensitive.  The CSeq header field serves to order transactions within a dialog, to provide a means to uniquely identify transactions, and to differentiate between new requests and request retransmissions.  Two CSeq header fields are considered equal if the sequence number and the request method are identical.  

请求中的CSeq报头字段包含一个十进制序列号和请求方法。序列号必须表示为32位无符号整数。CSeq的方法部分区分大小写。CSeq报头字段用于对对话中的事务进行排序，提供唯一标识事务的方法，并区分新请求和请求重传。如果序列号和请求方法相同，则认为两个CSeq报头字段相等。

Example:

实例

      CSeq: 4711 INVITE