RFC1582 - Extensions to RIP to Support Demand Circuits( 九 )

packets so should be set to zero.
For triggered response packets the rest of the datagram contains a
list of destinations, with information about each. Each entry in
this list contains the address family identifier (2 for IP), a
destination network or host, and the metric for it. The packet
format is intended to allow RIP to carry routing information for
several different protocols, identifiable by the family identifier.
The IP address is the usual Internet address, stored as 4 octets in
network order. The metric field contains a value between 1 and 15
inclusive, specifying the current metric for the destination, or the
value 16 (representing "infinity"), which indicates that the
destination is not reachable. Each route sent by a router supersedes
any previous route to the same destination from the same router.
The maximum datagram size is 508 octets, excluding UDP and IP
headers.
4. IP Routing Information Protocol Version 2
An enhancement to IP RIP to include subnetting has recently become
available [2]. This section only describes differences from that
RFC.
The triggered update mechanism can be supported by including the
triggered request (6), triggered response (7) and triggered
acknowledgement (8) commands described in the previous section.
The sequence number, fragment number and number of fragments fields
are included in triggered response and triggered acknowledgement
commands.
The triggered request packet should also contain the 4 extra octets
corresponding to the sequence number, fragment number and number of
fragments fields - but set to zero.
Because additional security information is included in RIP Version 2
packets, this MUST be appended to the triggered request and triggered
acknowledgement packets, as well as being present in the triggered
response packet.
The version number becomes 2. Other ASPects of packet layout follow
reference [2].
5. Netware Routing Information Protocol
This section should be read in conjunction with references [3], since
it only describes differences from the specification.
Netware [3] is the trade name of Novell Research"s protocols for
computer communication which are derived and extended from Xerox
Network System"s (XNS) protocols [4].
Netware supports a mechanism that allows routers on an internetwork
to exchange routing information using the Routing Information
Protocol (RIP) which runs over the Internetwork Packet Exchange (IPX)
protocol using socket number 453h.
Netware RIP and IP RIP share a common heritage, in that they are both
based on XNS RIP, but there is some divergence, mostly at the packet
format level to reflect the differing addressing schemes.
The triggered update mechanism can be applied to Netware RIP. To
support the mechanism outlined in this proposal the packet format for
Netware RIP is modified as shown in Figure 3.
Every datagram contains the following:
RIP OPERATION
Operations supported in standard Netware RIP are: request
(1) and response (2).
The fields sequence number, fragment number and number of
fragments MUST NOT be included in packets with these
operation values.
The following new operations are required (with values
chosen to be the same as for IP RIP commands):
0 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
- - - - - - - - - - - - - - - -
operation (2)
--------------- ---------------
The following new fields are inserted for some operations
0 1 2 3 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
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
sequence number (2)fragment (1) no of frags (1)