HP 4800G Series Configuration Manual page 412

RIPv2 message format
The format of RIPv2 message is similar to RIPv1.
Figure 1-2 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 can 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 1-3.
Figure 1-3 RIPv2 Authentication Message
Authentication Type: A value of 2 represents plain text authentication, while a value of 3 represents
MD5.
Authentication: Authentication data, including password information when plain text authentication
is adopted or including key ID, MD5 authentication data length and sequence number when MD5
authentication is adopted.
Figure 1-2 shows it.
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