Route based vs Policy based VPN match on each side?

Hello all,

Today, I had a discussion with my colleague about VPNs. Last week, I set up a VPN tunnel and showed him my VPN configuration which is a route based VPN. He told me that it is important that both sides needs to match if it is route based or policy based. So if I configure route based on my side, the customer/partner needs also to configure route based on their side. Now me personally, I've never heard of this before. I know of course that phase 1/ phase 2 needs to match on both sides, but I never thought of that it is important that each side needs (or rather best practise) to match when going for route based or policy based.

He did not have much time to explain unfortunately. I tried to look it up but could not find any answer to this question. I would appreciate if someone could explain this to me. Also, a reference to this would be very appreciative!

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Thanks.