Definition - What does Edge Router mean?
An edge router is a specialized router residing at the edge or boundary of a network. This router ensures the connectivity of its network with external networks, a wide area network or the Internet. An edge router uses an External Border Gateway Protocol, which is used extensively over the Internet to provide connectivity with remote networks.
Instead of providing communication with an internal network, which the core router already manages, an edge router may provide communication with different networks and autonomous systems.
This term is also sometimes known as an access router or core router.
Techopedia explains Edge Router
Edge routers use External BGP Protocol for data transmission because they are intermediary devices between two different networks and operate at the external or border layer of the network. There are several types of edge routers, including edge routers placed at the outer boundary of the network as an essential device for connecting the host network with the Internet. Whenever a node sends data on a network unmonitored by the host administrator, the data packet is sent to the last router on the authorized network, which is the edge router.
There are two types of edge routers, the subscriber edge router and label edge router. The subscriber edge router is used in scenarios where it serves at the border device. The label edge router is used in multiprotocol label switching (MPLS) and assigns labels to outbound data transmissions.