Software Router - Applications - Internet Connectivity and Internal Use

Internet Connectivity and Internal Use

Routers intended for ISP and major enterprise connectivity usually exchange routing information using the Border Gateway Protocol (BGP). RFC 4098 standard defines the types of BGP-protocol routers according to the routers' functions:

• Edge router: Also called a Provider Edge router, is placed at the edge of an ISP network. The router uses External BGP to EBGP protocol routers in other ISPs, or a large enterprise Autonomous System.
• Subscriber edge router: Also called a Customer Edge router, is located at the edge of the subscriber's network, it also uses EBGP protocol to its provider's Autonomous System. It is typically used in an (enterprise) organization.
• Inter-provider border router: Interconnecting ISPs, is a BGP-protocol router that maintains BGP sessions with other BGP protocol routers in ISP Autonomous Systems.
• Core router: A core router resides within an Autonomous System as a back bone to carry traffic between edge routers.
• Within an ISP: In the ISPs Autonomous System, a router uses internal BGP protocol to communicate with other ISP edge routers, other intranet core routers, or the ISPs intranet provider border routers.
• "Internet backbone:" The Internet no longer has a clearly identifiable backbone, unlike its predecessor networks. See default-free zone (DFZ). The major ISPs system routers make up what could be considered to be the current Internet backbone core. ISPs operate all four types of the BGP-protocol routers described here. An ISP "core" router is used to interconnect its edge and border routers. Core routers may also have specialized functions in virtual private networks based on a combination of BGP and Multi-Protocol Label Switching protocols.
• Port forwarding: Routers are also used for port forwarding between private internet connected servers.

• Voice/Data/Fax/Video Processing Routers: Commonly referred to as access servers or gateways, these devices are used to route and process voice, data, video, and fax traffic on the internet. Since 2005, most long-distance phone calls have been processed as IP traffic (VOIP) through a voice gateway. Voice traffic that the traditional cable networks once carried. Use of access server type routers expanded with the advent of the internet, first with dial-up access, and another resurgence with voice phone service.