This section provides recommendations that affect feature configuration.
Pay special attention to the expected scaling of routes in the network and the number of OSPF neighbors in a single VRF when you select configuration values for the isis l1-hellointerval and isis l1-hello-multiplier commands on IS-IS interfaces. The default values for these commands work well for most networks, including those using moderately-scaled routes.
The default values work well for 16,000 routes and 64 OSPF neighbors in a single VRF. However, in highly-scaled networks, you might need to configure higher values for these commands.
For example, if the total number of non IS-IS routes on a given BEB exceeds 16,000 in combination with approximately 128 OSPF neighbors in a single VRF, you should configure a value of 12 for isis l1-hellomultiplier, instead of using the default value of 3.
If the total number of non IS-IS routes on a given BEB exceeds 25,000 in combination with approximately 60,000 IS-IS routes that the BEB receives from other BEBs in the network, you should configure a value of 12 for isis l1-hellomultiplier, instead of using the default value of 3.