D-Link xStack DXS-3350SR Installation & User Manual - Rip Version 1 Message Format
DXS-3350SR Gigabit Layer 3 Switch
RIP Version 1 Message Format
There are two types of RIP messages: routing information messages and information requests. Both types use the same
format.
The COMMAND field specifies an operation according the following table:
Command
Meaning
1
Request for partial or full routing information
2
Response containing network-distance pairs from sender’s
routing table
3
Turn on trace mode (obsolete)
4
Turn off trace mode (obsolete)
5
Reserved for Sun Microsystem’s internal use
9 Update
Request
10 Update
Response
11 Update
Acknowledgement
RIP Command Codes
The field VERSION contains the protocol version number (1 in this case), and is used by the receiver to verify which
version of RIP the packet was sent.
RIP 1 Message
RIP is not limited to TCP/IP. Its address format can support up to 14 octets (when using IP, the remaining 10 octets must be
zeros). Other network protocol suites can be specified in the Family of Source Network field (IP has a value of 2). This
will determine how the address field is interpreted.
RIP specifies that the IP address, 0.0.0.0, denotes a default route.
The distances, measured in router hops are entered in the Distance to Source Network, and Distance to Destination Network
fields.
RIP 1 Route Interpretation
RIP was designed to be used with classed address schemes, and does not include an explicit subnet mask. An extension to
version 1 does allow routers to exchange subnetted addresses, but only if the subnet mask used by the network is the same
as the subnet mask used by the address. This means the RIP version 1 cannot be used to propagate classless addresses.
Routers running RIP version 1 must send different update messages for each IP interface to which it is connected.
Interfaces that use the same subnet mask as the router’s network can contain subnetted routes, other interfaces cannot. The
router will then advertise only a single route to the network.
RIP Version 2 Extensions
RIP version 2 includes an explicit subnet mask entry, so RIP version 2 can be used to propagate variable length subnet
addresses or CIDR classless addresses. RIP version 2 also adds an explicit next hop entry, which speeds convergence and
helps prevent the formation of routing loops.
RIP2 Message Format
The message format used with RIP2 is an extension of the RIP1 format:
139
RIP version 2 also adds a 16-bit route tag that is retained and sent with router updates. It can be used to identify the origin
of the route.