Technical Tip: How to redistribute routes from other sources in a dynamic routing protocol (RIP, OSPF, BGP, IS-IS, Static Routes, Connected Subnets)

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Description

This article describes routing protocol behavior on a FortiGate running one or more dynamic routing protocols, and explains how to redistribute routes from other sources.

Scope

All versions of FortiOS, except for IS-IS supported since 4.0MR2.

Solution

On a FortiGate running one or more dynamic routing protocol(s), each individual routing protocol will by default not advertise routes from another route source.

Route redistribution must be specifically configured for each routing protocol, as per the examples provided hereafter.

For more information about routing protocols, consult the FortiOS™ Dynamic Routing Guide.

The CLI route redistribution commands are common to each routing protocol. Each other routing source can be advertised in any other routing protocol.

• Example 1: Redistribute static routes in RIP.

config router rip

    config redistribute static

        set status enable

    end

end

• Example 2: Redistribute RIP routes in BGP.

config router bgp

    config redistribute rip

        set status enable

    end

end

• Example 3: Redistribute OSPF learned routes in BGP.

config router bgp

    config redistribute ospf

        set status enable

    end

end

• Example 4: Redistribute IS-IS routes and connected subnets in OSPF.

config router ospf
    config redistribute connected
        set status enable
    end

    config redistribute isis

        set status enable

    end

end

In general, if the below commands are executed exactly, all settings will be visible:

For BGP Protocol:

   config router bgp

config redistribute ? <- With a question mark, all possible settings will be visible and what can be redistributed via BGP will be shown. (The same applies to OSPF.)
*name Distribute list entry name.
   connected disable
   isis disable
   ospf disable
   rip disable
   static disable

For OSPF Protocol:

  config router ospf

  config redistribute ? 
*name Distribute list entry name.
   connected disable
   isis disable
   bgp disable
   rip disable
   static disable

Note:

In REDISTRIBUTION under BGP, it is a good practice to use ROUTE-MAP along with 'redistribute connected' if one or more of the connected routes/interfaces/IP is used in peering with the BGP neighbor. If this is not done, the connected routes will be announced into BGP and can cause routing issues.

Related article:

Technical Tip: How to redistribute a default route in OSPF.