Which attribute is not part of the BGP extended community when a PE creates a VPN-IPv4 route while running OSPF between PE-CE?
Correct Answer: E
Explanation/Reference:
Explanation:
By process of elimination, from RFC 4577:
For every address prefix that was installed in the VRF by one of its associated OSPF instances, the PE must create a VPN-IPv4 route in BGP. Each such route will have some of the following Extended Communities attributes:
The OSPF Domain Identifier Extended Communities attribute. If the OSPF instance that installed the route has a non-NULL primary Domain Identifier, this MUST be present; if that OSPF instance has only a NULL Domain Identifier, it MAY be omitted.
OSPF Route Type Extended Communities Attribute. This attribute MUST be present. It is encoded with a two-byte type field, and its type is 0306. OSPF Router ID Extended Communities Attribute. This OPTIONAL attribute specifies the OSPF Router ID of the system that is identified in the BGP Next Hop attribute. More precisely, it specifies the OSPF Router Id of the PE in the OSPF instance that installed the route into the VRF from which this route was exported.
MED (Multi_EXIT_DISC attribute). By default, this SHOULD be set to the value of the OSPF distance associated with the route, plus 1.
Reference. https://tools.ietf.org/html/rfc4577