to the backbone
(idiomatic) Through and through; thoroughly; entirely.
Synonyms: to the bone, to the core; see also Thesaurus:to the full
All other areas are connected to it, and inter-area routing happens via routers connected to the backbone area and to their own associated areas. Source: Internet
All OSPF areas must connect to the backbone area. Source: Internet
Each of these is distinguished from naturally occurring DNA or RNA by changes to the backbone of the molecule. Source: Internet
Further assume that area 0.0.0.2 has no direct connection to the backbone, but this area does have a connection to area 0.0.0.1. Source: Internet
With hierarchical routing, only core routers connected to the backbone are aware of all routes. Source: Internet