Hack the Route Start free Open app Forwarding
Route summarisation
One route standing for many: a shorter prefix that covers several networks behind the same next hop.
10.0.4.0/26, 10.0.4.64/27 and 10.0.4.96/28 all sit inside 10.0.4.0/24, so a router that reaches them all
through the same neighbour needs only that one route. Smaller tables, fewer updates, and a flapping network far away
changes nothing upstream. It only works when addresses were planned in blocks. Because longest-prefix match
picks the most specific route, a summary can have exceptions; and because it covers unused addresses too, the router
that owns the block needs a null route for it.