The user can instruct IGP to not include all interfaces participating in a specific IS-IS level or OSPF area in the SPF LFA computation. This reduces the LFA SPF calculation where it is not needed.
classic CLI
config>router>isis>level>loopfree-alternate-exclude
config>router>ospf>area>loopfree-alternate-exclude
MD-CLI
configure router isis level loopfree-alternate-exclude
configure router ospf area loopfree-alternate-exclude
The user can also exclude a specific IP interface from the LFA SPF computation by IS-IS or OSPF using the following commands.
classic CLI
config>router>isis>interface>loopfree-alternate-exclude
config>router>ospf>area>interface>loopfree-alternate-exclude
MD-CLI
configure router isis interface loopfree-alternate exclude
configure router ospf area interface loopfree-alternate exclude
When an interface is excluded from the LFA SPF in IS-IS, it is excluded in both level 1 and level 2. When an interface is excluded from the LFA SPF in OSPF, it is excluded in all areas. However, the preceding OSPF command can only be executed under the area in which the specified interface is primary; when enabled, the interface is excluded in that area and in all other areas where the interface is secondary. If the user attempts to apply it to an area where the interface is secondary, the command fails.
The user can also apply the loopfree-alternate-exclude commands for an OSPF instance within a VPRN service.
classic CLI
config>service>vprn>ospf>area>loopfree-alternate-exclude
config>service>vprn>ospf>area>if>loopfree-alternate-exclude
MD-CLI
configure service vprn ospf area loopfree-alternate-exclude
configure service vprn ospf area interface loopfree-alternate-exclude