Advertising link TE attributes by using IGP TE extension
Both OSPF and IS-IS are extended to advertise link TE attributes. The extensions are called OSPF TE and IS-IS TE. If both OSPF TE and IS-IS TE are available, OSPF TE takes precedence.
Configuring OSPF TE
OSPF TE uses Type-10 opaque LSAs to carry the TE attributes for a link. Before you configure OSPF TE, you must enable opaque LSA advertisement and reception by using the opaque-capability enable command. For more information about opaque LSA advertisement and reception, see Layer 3—IP Routing Configuration Guide.
MPLS TE cannot reserve resources and distribute labels for an OSPF virtual link, and cannot establish a CRLSP through an OSPF virtual link. Therefore, make sure no virtual link exists in an OSPF area before you configure MPLS TE.
To configure OSPF TE:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter OSPF view. | ospf [ process-id ] | N/A |
3. Enable opaque LSA advertisement and reception. | opaque-capability enable | By default, opaque LSA advertisement and reception are enabled. For more information about this command, see Layer 3—IP Routing Command Reference. |
4. Enter area view. | area area-id | N/A |
5. Enable MPLS TE for the OSPF area. | mpls te enable | By default, MPLS TE is disabled for an OSPF area. |
Configuring IS-IS TE
IS-IS TE uses a sub-TLV of the extended IS reachability TLV (type 22) to carry TE attributes. Because the extended IS reachability TLV carries wide metrics, specify a wide metric-compatible metric style for the IS-IS process before enabling IS-IS TE. Available metric styles for IS-IS TE include wide, compatible, or wide-compatible. For more information about IS-IS, see Layer 3—IP Routing Configuration Guide.
On IS-IS enabled interfaces, set the MTU to a minimum of 512 bytes to ensure that IS-IS LSPs of different lengths can be flooded to the network.
To configure IS-IS TE:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Create an IS-IS process and enter IS-IS view. | isis [ process-id ] | By default, no IS-IS process exists. |
3. Specify a metric style. | cost-style { narrow | wide | wide-compatible | { compatible | narrow-compatible } [ relax-spf-limit ] } | By default, only narrow metric style packets can be received and sent. For more information about this command, see Layer 3—IP Routing Command Reference. |
4. Enable MPLS TE for the IS-IS process. | mpls te enable [ Level-1 | Level-2 ] | By default, MPLS TE is disabled for an IS-IS process. |
5. Specify the types of the sub-TLVs for carrying DS-TE parameters. | te-subtlv { bw-constraint value | unreserved-subpool-bw value } * | By default, the bw-constraint parameter is carried in sub-TLV 252, and the unreserved-bw-sub-pool parameter is carried in sub-TLV 251. |