Via              = ( "Via" | "v") ":" 1#( sent-protocol sent-by
                     *( ";" via-params ) [ comment ] )
  via-params       = via-hidden | via-ttl | via-maddr 
                   | via-received | via-branch | via-extension
  via-hidden       = "hidden"
  via-ttl          = "ttl" "=" ttl
  via-maddr        = "maddr" "=" host
  via-received	   = "received" "=" host
  via-branch       = "branch" "=" token
  via-extension    = generic-param
  sent-protocol    = protocol-name "/" protocol-version "/" transport
  protocol-name    = "SIP" | token
  protocol-version = token
<<<<<<< via_syntax.txt
  transport        = "UDP" | "TCP" | token
  sent-by          = host [ ":" port ]
=======
  transport        = "UDP" | "TCP" | "TLS" | "SCTP" | other-transport
  sent-by          = host [ ":" port ]
  ttl              = 1*3DIGIT     ; 0 to 255
>>>>>>> 1.4