H3C Technologies H3C S7500E Series Switches - Manual (Page 101)

3-19
To do… Use the command... Remarks
Exit to OSPF view quit ––
z
For more information about OSPF opaque LSA, see OSPF Configuration in the Layer 3 - IP
Routing Configuration Guide .
z
MPLS TE cannot reserve resources and distribute labels on OSPF virtual links, that is, MPLS TE
cannot establish an LSP tunnel through an OSPF virtual link. Therefore, make sure there is no
virtual links in the OSPF routing domain when configuring OSPF TE.
Configuring IS-IS TE
Configure IS-IS TE if the routing protocol is IS-IS and a dynamic signaling protocol is used for MPLS
TE tunnel setup. In case both OSPF TE and IS-IS TE are available, OSPF TE takes priority.
The IS-IS TE extension uses the sub-TLV of IS reachability TLV (type 22) to carry TE attributes.
Before configuring IS-IS TE, you need to configure the IS-IS wide metric style, which can be wide,
compatible, or wide-compatible.
z
According to RFC 3784, the length of the IS reachability TLV (type 22) may reach the maximum of
255 octets in some cases.
z
For an IS-IS LSP to carry this type of TLV and to be flooded normally on all interfaces with IS-IS
enabled, the MTU of any IS-IS enabled interface, including 27 octets of LSP header and two
octets of TLV header, cannot be less than 284 octets. If an LSP must also carry the authentication
information, the minimum MTU needs to be recalculated according to the packet structure.
In a word, with the TE feature, the MTU of any interface with IS-IS enabled is recommended to be
equal to or greater than 512 octets to guarantee that IS-IS LSPs can be flooded on the network.
Follow these steps to configure IS-IS TE:
To do… Use the command... Remarks
Enter system view system-view ––
Enter IS-IS view isis [ process-id ] ––
Configure the wide metric attribute
of IS-IS
cost-style { narrow | wide |
wide-compatible | { compatible |
narrow-compatible }
[ relax-spf-limit ] }
Required
By default, IS-IS uses narrow
metric style.