Description
This article describes how to advertise an aggregate route via RIP.
Solution
The Benefits of Aggregate Routes.
Rather than advertise a number of host routes, it is necessary to advertise a subnet with a shorter prefix that encompasses all of these host routes.
One special example of this is advertising a subnet that encompasses a series of Virtual IPs.
Case Study: RIP & Virtual IPs.
Let's say that there is the following Virtual IPs:
69.25.56.17
69.25.56.18
69.25.56.19
And there are on an external interface with IP address 207.173.5.120/24.
To advertise a network 69.25.56.16/29 so that the VIPs are reachable from the Internet.
Warning:
Aggregation might cover more than the existing individual VIP addresses one wants to aggregate.
In this example, 69.25.56.16/29 has got host range from 69.25.56.17 to 69.25.56.22
Multiple aggregates ranges might be necessary in case of non-contiguous IP addresses.
To configure.
Note.
This assumes there is a RIP running between this FortiGate and another networking device running RIP.
Because the VIPs is not treated as 'connected' networks, use of the 'network' statement is inappropriate.
Instead, it is possible to create what some vendors call a null, or 'dummy' route for 69.25.56.16/29 and then redistribute static routes into RIP.
For example:
# config router rip
# config redistribute "static"
set status enable
end
config router static
edit 20
set dst 69.25.56.16 255.255.255.248
next
Note.
When entering the static route from the GUI, it is necessary to enter a distance, outbound interface and gateway IP (use the IP of the interface) but none of these values are really important, the key is to advertise that network to other RIP devices.
To troubleshoot.
Fortigate-100 # get router info rip database
Codes: R - RIP, K - Kernel, C - Connected, S - Static, O - OSPF, I - IS-IS, B - BGP
Network Next Hop Metric From If Time
R 0.0.0.0/0 192.168.1.101 2 192.168.1.101 internal 02:47
S 1.1.1.0/24 1 external
C 192.168.1.0/24 1 internal
C 192.168.3.0/24 1 external
Other commands:
diag net route list
get router info rip interface
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