Chapter 16: Dynamic Routing Protocols
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
471
Each router in a Level 1 area builds an area unique LSP database with its peers. Disjointed Level 1 areas must be joined
together via a Level 2 (backbone) area.
Figure 82:
IS-IS Level 1 and 2 Routing
By default, Level 1 areas are considered "stub" areas because they rely on a default route to forward traffic out of the area.
However, route leaking from Level 2 and Level 1 areas allows for more intelligent inter-area routing.