Hello everyone,
Today I will share with you what is the black-hole route and route black hole.
Black-hole route
The null interface is a route to the null interface. A null interface is a virtual interface that cannot be configured with an IP address. All packets forwarded to the interface are discarded. Therefore, a blackhole route is added to all routes that may generate a route loop due to an interruption. For example, in an environment where a default route is configured, if a routing entry of the router is interrupted due to a fault, a routing loop may occur on the two routers.
Route black hole
Route black holes are usually generated when aggregation and return routes are summarized on the network border. Sometimes, some network segments do not exist on the internal network but are included in the summarized network segment, if the default route is configured on the aggregated boundary device, some problems may occur. In this case, if a data packet is sent to the router that does not belong to the network segment (but also included in the summary network segment) that does not exist in the internal network, the router does not find the corresponding route according to the longest matching principle, but can return to the original router according to the default route, as a result, a loop is formed, and the packet is discarded until the TTL value expires.
