The format of RIP is not detailed. Here we will analyze the specific content of the RIP group format. For the RIP Protocol, the two formats of version 1 and Version 2 are different. What are the specific formats?
RIP group format
The grouping formats of ip rip and IP RIP2 are described below.
1. RIP group format
· Command -- indicates whether the group is a request or a response. the request group requires the router to send all or part of its route table. the Response Group can be an active periodic route update or response to the request. large route tables can use multiple RIP groups to transmit information.
· Version number -- indicates the RIP version used. This field can notify different versions of incompatibility.
· Zero -- unused.
· Address family flag (AFI) -- specifies the address family in use. RIP is designed to carry routing information of different protocols. each item has an address family flag to indicate the address type used. The AFI of the IP is 2.
· Address -- specify the IP address of the item.
· Metric -- indicates the number of hops that have taken place during the target process. The valid path value is between 1 and 15, and 16 indicates the inaccessible path.
Note: up to 25 AFI, address, and metric fields can be contained in an ip rip group. That is, up to 25 IP address entries can be contained in a RIP group.
2. RIP2 group format
The RIP2 specification (RFC1723) allows the RIP group format to contain more information and provides a simple authentication mechanism, such.
· Command -- indicates whether the group is a request or a response. the request group requires the router to send all or part of its route table. the Response Group can be an active periodic route update or response to the request. large route tables can use multiple RIP groups to transmit information.
· Version -- indicates the RIP version used. In the RIP group that implements RIP2 or performs authentication, this value is 2.
· Not used -- the value is 0.
· Address family flag (AFI) -- specifies the address family in use. RIP is designed to carry routing information of different protocols. each item has an address family flag to indicate the address type used. The AFI of the IP is 2. if the AFI of the first item is 0 xFFFF, the remaining part of the item is the authentication information. currently, the only authentication type is simple password.
· Route tag-provides a method to distinguish between internal routes learned by RIP) and external Routes learned by other protocols.
· IP Address -- specify the IP address of this item.
· Subnet mask -- contains the subnet mask of this item. If this field is 0, the subnet mask is not specified.
· Next hop -- specify the IP address of the next hop.
· Metric -- indicates the number of hops that have taken place during the target process. The valid path value is between 1 and 15, and 16 indicates the inaccessible path.
Note: up to 25 AFI, address, and metric fields can be contained in an ip rip group. That is, up to 25 IP address entries can be contained in a RIP group. if AFI indicates authentication information, there are only 24 route table entries.