rfc2776.txt

<VC++网络游戏建摸与实现>源代码

Handley, et al.             Standards Track                    [Page 11]

RFC 2776                          MZAP                     February 2000


   "Big" scope bit (B):
      If clear, indicates that the addresses in the scoped range are not
      subdividable, and that address allocators may utilize the entire
      range.  If set, address allocators should not use the entire
      range, but should learn an appropriate sub-range via another
      mechanism (e.g., AAP [7]).

   Packet Type (PTYPE):
      The packet types defined in this document are:
         0: Zone Announcement Message (ZAM)
         1: Zone Limit Exceeded (ZLE)
         2: Zone Convexity Message (ZCM)
         3: Not-Inside Message (NIM)

   Address Family:
      The IANA-assigned address family number [10,11] identifying the
      address family for all addresses in the packet.  The families
      defined for IP are:
         1: IPv4
         2: IPv6

   Name Count:
      The number of encoded zone name blocks in this packet.  The count
      may be zero.

   Zone Start Address: 32 bits (IPv4) or 128 bits (IPv6)
      This gives the start address for the scope zone boundary.  For
      example, if the zone is a boundary for 239.1.0.0 to 239.1.0.255,
      then Zone Start Address is 239.1.0.0.

   Zone End Address: 32 bits (IPv4) or 128 bits (IPv6)
      This gives the ending address for the scope zone boundary.  For
      example, if the zone is a boundary for 239.1.0.0 to 239.1.0.255,
      then Zone End Address is 239.1.0.255.

   Message Origin: 32 bits (IPv4) or 128 bits (IPv6)
      This gives the IP address of the interface that originated the
      message.

   Zone ID Address: 32 bits (IPv4) or 128 bits (IPv6)
      This gives the lowest IP address of a boundary router that has
      been observed in the zone originating the message.  Together with
      Zone Start Address and Zone End Address, it forms a unique ID for
      the zone.  Note that this ID is usually different from the ID of
      the Local Scope zone in which the origin resides.






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RFC 2776                          MZAP                     February 2000


   Encoded Zone Name:
      +--------------------+
      |D| Reserved (7 bits)|
      +--------------------+
      | LangLen (1 byte)   |
      +--------------------+-----------+
      | Language Tag (variable size)   |
      +--------------------+-----------+
      | NameLen (1 byte)   |
      +--------------------+-----------+
      | Zone Name (variable size)      |
      +--------------------------------+

      The first byte contains flags, of which only the high bit is
      defined.  The other bits are reserved (sent as 0, ignored on
      receipt).

   "Default Language" (D) bit:
      If set, indicates a preference that the name in the following
      language should be used if no name is available in a desired
      language.

   Language tag length (LangLen): 1 byte
      The length, in bytes, of the language tag.

   Language Tag: (variable size)
      The language tag, such as "en-US", indicating the language of the
      zone name.  Language tags are described in [6].

   Name Len:
      The length, in bytes, of the Zone Name field.  The length MUST NOT
      be zero.

   Zone Name: multiple of 8 bits
      The Zone Name is an ISO 10646 character string in UTF-8 encoding
      [4] indicating the name given to the scope zone (eg: "ISI-West
      Site").  It should be relatively short and MUST be less than 256
      bytes in length.  White space SHOULD be stripped from the
      beginning and end of each name before encoding, to avoid
      accidental conflicts.

   Padding (if needed):
      The end of the MZAP header is padded with null bytes until it is
      4-byte aligned.







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RFC 2776                          MZAP                     February 2000


5.1.  Zone Announcement Message

   A Zone Announcement Message has PTYPE=0, and is periodically sent by
   a ZBR for each scope for which it is a boundary, EXCEPT:

   o  the Local Scope

   o  the Link-local scope

   The format of a Zone Announcement Message is shown below:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                               MZAP Header
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      ZT       |     ZTL       |           Hold Time           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Local Zone ID Address 0                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Router Address 1                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Local Zone ID Address 1                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                .....
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Router Address N                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Local Zone ID Address N                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The fields are defined as follows:

   Zones Traveled (ZT): 8 bits
      This gives the number of Local Zone IDs contained in this message
      path.

   Zones Traveled Limit (ZTL): 8 bits
      This gives the limit on number of local zones that the packet can
      traverse before it MUST be dropped.  A value of 0 indicates that
      no limit exists.

   Hold Time:
      The time, in seconds, after which the receiver should assume the
      scope no longer exists, if no subsequent ZAM is received.  This
      should be set to [ZAM-HOLDTIME].





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RFC 2776                          MZAP                     February 2000


   Zone Path: multiple of 64 bits (IPv4) or 256 bits (IPv6)
      The zone path is a list of Local Zone ID Addresses (the Zone ID
      Address of a local zone) through which the ZAM has passed, and IP
      addresses of the router that forwarded the packet.  The origin
      router fills in the "Local Zone ID Address 0" field when sending
      the ZAM.  Every Local Scope router that forwards the ZAM across a
      Local Scope boundary MUST add the Local Zone ID Address of the
      local zone that the packet of the zone into which the message is
      being forwarded, and its own IP address to the end of this list,
      and increment ZT accordingly.  The zone path is empty which the
      ZAM is first sent.

5.2.  Zone Limit Exceeded (ZLE)

   The format of a ZLE is shown below:
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                               MZAP Header
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      ZT       |     ZTL       |         Hold Time             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Local Zone ID Address 0                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Router Address 1                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Local Zone ID Address 1                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                .....
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Router Address N                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Local Zone ID Address N                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   All fields are copied from the ZAM, except PTYPE which is set to one.

5.3.  Zone Convexity Message

   A Zone Announcement Message has PTYPE=2, and is periodically sent by
   a ZBR for each scope for which it is a boundary (except the Link-
   local scope).  Note that ZCM's ARE sent in the Local Scope.

   Unlike Zone Announcement Messages which are sent to the [MZAP-LOCAL-
   GROUP], Zone Convexity Messages are sent to the [ZCM-RELATIVE-GROUP]
   in the scope zone itself.  The format of a ZCM is shown below:





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RFC 2776                          MZAP                     February 2000


    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                               MZAP Header
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     ZNUM      |  unused       |           Hold Time           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          ZBR Address 1                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                .....
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          ZBR Address N                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The fields are as follows:

   Number of ZBR addresses (ZNUM): 8 bits
      This field gives the number of ZBR Addresses contained in this
      message.

   Hold Time:
      The time, in seconds, after which the receiver should assume the
      sender is no longer reachable, if no subsequent ZCM is received.
      This should be set to [ZCM-HOLDTIME].

   ZBR Address: 32 bits (IPv4) or 128 bits (IPv6)
      These fields give the addresses of the other ZBRs from which the
      Message Origin ZBR has received ZCMs but whose hold time has not
      expired.  The router should include all such addresses which fit
      in the packet, preferring those which it has not included recently
      if all do not fit.

5.4.  Not-Inside Message

   A Not-Inside Message (NIM) has PTYPE=3, and is periodically sent by a
   ZBR which knows that a scope X does not nest within another scope Y
   ("X not inside Y"):

   The format of a Not-Inside Message is shown below:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                               MZAP Header
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Not-Inside Zone Start Address                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




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RFC 2776                          MZAP                     February 2000


   The fields are as follows:

   MZAP Header:  Header fields identifying the scope X.  The Name Count
      may be 0.

   Not-Inside Zone Start Address: 32 bits (IPv4) or 128 bits (IPv6) This
      gives the start address for the scope Y.

6.  Message Processing Rules