Perimeter router, internal router, Firewall

Perimeter router, internal router, Firewall

Perimeter router-

The perimeter router is basically a standard router that provides serial connection to the outside world and a LAN connection to the internal network. The perimeter router provides filtering of outside traffic to implement basic security. This device could be running the firewall feature set for additional security options.

www.etutorials.org

http://en.wikipedia.org/wiki/Open_Shortest_Path_First#Internal_router

Internal router-

An internal router is a router that has Open Shortest Path First (OSPF) neighbour relationships with interfaces in the same area. An internal router has all its interfaces in a single area. OSPF is a routing protocol that is used to allow routers to dynamically learn routes from other routers and to advertise routes to other routers

Firewall-

Lastly, a firewall is a device that either separates or joins the inside network to the dirty DMZ and any optional protected DMZs. However, the firewall can also be a router- running firewall feature set. Although this is possible, it is generally better to use dedicated device performing only security features and leave the routing and serving duty to other devices.

A typical firewall usually has two or more LAN interfaces, one for the inside network, and the other for the outside network.

http://etutorials.org/Networking/Cisco+Certified+Security+Professional+Certification/Part+II+Securing+the+Network+Perimeter/Chapter+5+Securing+Cisco+Perimeter+Routers/Perimeter+Router+Terms+and+Concepts/

http://www.inetdaemon.com/tutorials/internet/ip/routing/ospf/index.shtml