Which configuration resolves this issue?

An engineer configured a company’s multiple area OSPF head office router and Site A cisco routers with VRF lite.

Each site router is connected to a PE router of an MPLS backbone.

After finishing both site router configurations, none of the LSA 3,4 5, and 7 are installed at Site A router.

Which configuration resolves this issue?
A . configure capability vrf-lite on Site A and its connected PE router under router ospf 1 vrf abc
B . configure capability vrf-lite on Head Office and its connected PE router under router ospf 1 vrf abc
C . configure capability vrf-lite on both PE routers connected to Head Office and Site A routers under router ospf 1 vrf abc
D . configure capability vrf-lite on Head Office and Site A routers under router ospf 1 vrf abc

View Answer

Answer: A

Explanation

In this case both Head Office and Site A routers run VRF (and OSPF) although they are CE routers.

So we must configure “capability vrf-lite” on them too.

For your information, the capability vrf-lite command disables the DN-bit (down bit) and domain-tag checks in OSPF. Since the CE router acts as the PE router in VRF-lite, these checks should be disabled, because the PE routers advertise VPN routes with DN-bit set to the CE routers. If the CE routers receive routes with DN-bit set, it will discard them. Hence, the checks should be disabled.