A police records bureau attaches an OSPF CE domain to an MPLS VPN PE. Which loop-prevention concepts should engineers keep in view?
Select an answer to reveal the explanation.
Short Explanation
OSPF across a VPN can accidentally learn its own routes back through another PE—classic loop fuel. Down-bit and domain-ID/domain-tag style tools exist so Type 3s and external-ish info don’t boomerang. Ignore them and the CE domain gets weird fast.
Full Explanation
When OSPF is used as PE-CE in MPLS L3VPN, routes redistributed via MP-BGP and re-injected into OSPF at remote sites can create loops without safeguards. Mechanisms such as the down-bit for summary routes and domain-ID/domain-tag behavior for external route handling are key conceptual controls. Assuming OSPF PE-CE needs no loop prevention, relying only on CE LAN BGP communities, or switching to RIPv2 as a universal fix misses the OSPF-specific design issue.