mpls/ldp question

If i have two directly connected bgp neighbors in mpls vpn l3 scenario (and they even peer with directly connected endpoints), why is it that -mpls ip- still needs to be enabled on that link, when there are no routers inbetween?

r1

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Comments

marlon23

because your VPNv4 prefixes carry label with them to identify VPN, even you don't need outer label to get to the next-hop, you still need inner label to identify VPN. Hence you need to encapsulate to MPLS, so need MPLS running on the interface.

acidsatyr

marlon23 wrote: »

because your VPNv4 prefixes carry label with them to identify VPN, even you don't need outer label to get to the next-hop, you still need inner label to identify VPN. Hence you need to encapsulate to MPLS, so need MPLS running on the interface.

aha! got it.

Because i thought that that's what bgp does puts the inner VPN label. In fact if i do:
sh ip cef vrf VPN_A <some_cust_route> even without mpls enabled, cef still shows the label assigned by BGP.

So mpls is still needed to actualy "put" that inner label on?

Thanks so much.

edit: is there a way for bgp to do that, so that i don't run mpls but vpnv4 are still reachable between two directly connected bgp peers?