Different methods to advertise a default route in BGP Part 3:

In this post, we’ll go through the 3^rd method to advertise a default route in BGP.

I’ve removed the neighbour x.x.x.x default-originate command.

3^rd method: Using default-information originate command (after redistributing the static route in BGP)

I’ll first create a default static route.

Above is the output from R1s routing table confirming that there is a static default route entry.

Now, I’ll redistribute this static route into BGP.

 

Let’s look at R2 and R3s routing table now and have a look if we can see a default route entry.

 

Even after redistributing the static route (default route in this case), we still cannot see 0.0.0.0 on R2 and R3.

We’ll have to configure default-information originate command on R1 under the BGP process.

 

 

 

Why do we have to use default-information originate command after redistributing the static route in BGP to advertise the default route to its BGP neighbors?

 This is done only to protect against someone accidently redistributing a default route into BGP which could result in a disaster.