+                           Address[1]                          +
   |                                                               |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                                                               +
   |                                                               |
   +                           Address[2]                          +
   |                                                               |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   .                               .                               .
   .                               .                               .
   .                               .                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                                                               +
   |                                                               |
   +                           Address[n]                          +
   |                                                               |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Next Header          8-bit selector.  Identifies the type of header
                        immediately following the Routing header.
                        Uses the same values as the IPv4 Protocol field
                        [RFC-1700 et seq.].

   Hdr Ext Len          8-bit unsigned integer.  Length of the
                        Routing header in 8-octet units, not including
                        the first 8 octets.  For the Type 0 Routing
                        header, Hdr Ext Len is equal to two times the
                        number of addresses in the header, and must
                        be an even number less than or equal to 46.

   Routing Type         0.



 
RFC 1883                   IPv6 Specification              December 1995


   Segments Left        8-bit unsigned integer.  Number of route
                        segments remaining, i.e., number of explicitly
                        listed intermediate nodes still to be visited
                        before reaching the final destination.
                        Maximum legal value = 23.

   Reserved             8-bit reserved field.  Initialized to zero for
                        transmission; ignored on reception.

   Strict/Loose Bit Map
                        24-bit bit-map, numbered 0 to 23, left-to-right.
                        Indicates, for each segment of the route, whether
                        or not the next destination address must be a
                        neighbor of the preceding address: 1 means strict
                        (must be a neighbor), 0 means loose (need not be
                        a neighbor).

   Address[1..n]        Vector of 128-bit addresses, numbered 1 to n.


   Multicast addresses must not appear in a Routing header of Type 0, or
   in the IPv6 Destination Address field of a packet carrying a Routing
   header of Type 0.

   If bit number 0 of the Strict/Loose Bit Map has value 1, the
   Destination Address field of the IPv6 header in the original packet
   must identify a neighbor of the originating node.  If bit number 0
   has value 0, the originator may use any legal, non-multicast address
   as the initial Destination Address.

   Bits numbered greater than n, where n is the number of addresses in
   the Routing header, must be set to 0 by the originator and ignored by
   receivers.

   A Routing header is not examined or processed until it reaches the
   node identified in the Destination Address field of the IPv6 header.
   In that node, dispatching on the Next Header field of the immediately
   preceding header causes the Routing header module to be invoked,
   which, in the case of Routing Type 0, performs the following
   algorithm:












 
RFC 1883                   IPv6 Specification              December 1995