BGP Backdoor feature

Hello,

I was labbing BGP Backdoor feature and notices, eBGP peers still advertise network specified in network backdoor command to their peers, even when they have same route learned from IGP and installed into FIB.

All documentation specify that network described in backdoor commend does not advertised to neighbors.

https://www.cisco.com/c/en/us/td/docs/ios/iproute_bgp/command/reference/irg_book/irg_bgp4.html#wp1145478

A backdoor network is treated as a local network, except that it is not advertised.

I have simple topology, like:

R1 --- eBGP --- R2 ---- eBGP --- R3

I make network backdoor command on R2 for R1 routes. Those routes are still visible on R3. Event when I run parallel link with EIGRP between R1 and R2, and R2 prefers EIGRP routes.

Could you please explain this behavior.

Thanks in advance,
Giorgi

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