OSPF Extensions for MPLS TE

OSPF Extensions for MPLS TE

• Three new LSAs were defined called Opaque LSAs. Opaque LSA type 9 has a flooding scope limited to local-link. Opaque LSA type 10 has a flooding scope limited to the area (intra-area) and Opaque LSA type 11 has a flooding scope that is autonomous system wide (inter-area like LSA type 5).
• MPLS TE uses LSA type 10 for intra-area MPLS TE.
• A new bit was defined ‘O’ in the Options field of OSPF Hello packet header. It indicates whether a router is capable of sending and receiving Opaque LSAs. The Options field is present in OSPF Hello, DBD packets and all LSAs.
• The TE LSA Type 10 carries one or more TLVs. These TLVs carry specific MPLS TE data.
• The Router TLV carries the router ID for TE.
• The Link TLV carries a set of sub-TLVs describing a single link for MPLS TE.

The Link Type indicates whether the link is point-to-point or multi-access.

The Link ID identifies the other end of the link. It is set to the router-id of the neighbor if the link is p2p. If the link is multi-access (like Ethernet), the Link ID is set to the IP address of the DR. It is same as contents of router-LSA.

The Local Interface IP address specifies the IP address(es) of the interface corresponding to this link. If the interface has multiple IP addresses, all addresses are mentioned.

The Remote Interface IP address specifies the IP address(es) of the neighbor’s interface corresponding to this link. This and local address are used to distinguish multiple parallel links between routers. If the Link type is multi-access, the Remote Interface IP address could be set to 0.0.0.0

The Traffic Engineering metric specifies the link metric for traffic-engineering purposes. This metric is configurable (administrative-weight) and hence could be different than OSPF metric.

The Maximum Bandwidth specifies the maximum bandwidth that can be used on the link from this router to the neighbor.

The Maximum Reservable Bandwidth specifies the maximum reservable bandwidth that can be reserved on the link from this router to the neighbor. This is configurable; default is Maximum Bandwidth.

The Unreserved Bandwidth specifies the amount of bandwidth not yet reserved at each of the eight (0-7) priority levels. The value corresponds to the bandwidth that can be reserved with a setup priority 0 through 7.

The Administrative Group contains a 4-byte bit mask assigned by the network administrator. Each set bit corresponds to one administrative group assigned to the interface. By convention, the least significant bit is referred to as “group 0” and most significant bit is referred to as “group 31”.

These parameters can be viewed using show ip ospf database opaque-area command on the head-end router.