3Com Switch 4800G 24-Port - Page 260

260 CHAPTER 27: RIP CONFIGURATION
Figure 69 RIPv1 Message Format
■ Command: Type of message. 1 indicates request, and 2 indicates response.
■ Version: Version of RIP, 0x01 for RIPv1.
■ AFI: Address Family Identifier, 2 for IP.
■ IP Address: Destination IP address of the route. It can be a natural network,
subnet or a host address.
■ Metric: Cost of the route.
RIPv2 message format
The format of RIPv2 message is similar with RIPv1. Figure 70 shows it.
Figure 70 RIPv2 Message Format
The differences from RIPv1 are stated as following.
■ Version: Version of RIP. For RIPv2 the value is 0x02.
■ Route Tag: Route Tag.
■ IP Address: Destination IP address. It could be a natural network address,
subnet address or host address.
■ Subnet Mask: Mask of the destination address.
■ Next Hop: If set to 0.0.0.0, it indicates that the originator of the route is the
best next hop; otherwise it indicates a next hop better than the originator of
the route.
RIPv2 authentication
RIPv2 sets the AFI field of the first route entry to 0xFFFF to identify authentication
information. See Figure 71.
Command
AFI
IP address
Version Must be zero
Must be zero
Must be zero
Must be zero
Metric
0 7 15 31
Route
Entries
Header
Command
AFI
IP address
Version Unused
Subnet mask
Next hop
Route tag
Metric
0 7 15 31
Route
Entries
Header