What Is OSPF?
? Has fast convergence
? Supports VLSM
? Has no hop count limitation
? Processes updates efficiently
? Selects paths based on bandwidth
? Supports equal-cost multipath

OSPF Terminology
This page introduces you to a variety of terms related to link-state technology and
OSPF. The following are basic terms to get you started:
n Interface—The connection between the router and one of its attached
networks. An interface is sometimes referred to as a link in OSPF literature.
n Link state—The status of a link between two routers, that is a router’s
interface and its relationship to its neighboring routers.
n Cost—The value assigned to a link. Rather than hops, link-state protocols
assign a cost to a link that is based on the speed of the media. A cost is
associated with the output side of each router interface, referred to as
“Interface Output Cost”.
n Autonomous System—A group of routers exchanging routing information
using a common routing protocol.
n Area—A collection of networks and routers that have the same area
identification. Each router within an area has the same link-state information.
A router within an area is an “internal” router.
n Neighbor—Two routers that have interfaces on a common network. Neighbor
relationship are usually discovered and maintained by the Hello protocol.
n Hello—Protocol used by OSPF to establish and maintain neighbor
relationship.
n Designated router (DR) and backup designated router (BDR)—A router that is
elected by all other routers on the same LAN to represent all the routers. Each
network has a DR and BDR. These routers have special responsibilities that
are discussed later in later.
n Neighborship list —A listing of all the neighbors to which a router has
established bi-directional communication. Not every pair of neighboring
routers become adjacent.
n Link-state database, also known as a topological database—A list of link-state
entries of all other routers in the internetwork. It shows the internetwork
topology. All routers within an area have identical link-state databases. The
link-state database is pieced together from LSAs generated by routers
n Routing table—The routing table (also known as forwarding database)
generated when an algorithm is run on the link-state database. Each router’s
routing table is unique.

OSPF Topologies
OSPF can run over multi-access networks or over non-broadcast networks. The
topology of a network has an impact on how adjacencies are created. Following
are the different topologies found in OSPF and covered in later.
n Broadcast Multi-access networks—Networks supporting many (more than
two) attached routers, together with the capability to address a single physical
message to all of the attached routers (broadcast). An Ethernet segment is an
example of a broadcast network.
n Point-to-point networks—A network that joins a single pair of routers. A T1
dedicated serial line is an example of a point-to-point network.
n Non-broadcast Multi-access networks—Networks supporting many (more than
two) routers, but having no broadcast capability. Frame Relay and X.25 are
example of Non-Broadcast Multiaccess Networks (NBMA)
                                       [This is the part one ,welcome for next]

What Is OSPF?
? Has fast convergence
? Supports VLSM
? Has no hop count limitation
? Processes updates efficiently
? Selects paths based on bandwidth
? Supports equal-cost multipath

OSPF Terminology
This page introduces you to a variety of terms related to link-state technology and
OSPF. The following are basic terms to get you started:
n Interface—The connection between the router and one of its attached
networks. An interface is sometimes referred to as a link in OSPF literature.
n Link state—The status of a link between two routers, that is a router’s
interface and its relationship to its neighboring routers.
n Cost—The value assigned to a link. Rather than hops, link-state protocols
assign a cost to a link that is based on the speed of the media. A cost is
associated with the output side of each router interface, referred to as
“Interface Output Cost”.
n Autonomous System—A group of routers exchanging routing information
using a common routing protocol.
n Area—A collection of networks and routers that have the same area
identification. Each router within an area has the same link-state information.
A router within an area is an “internal” router.
n Neighbor—Two routers that have interfaces on a common network. Neighbor
relationship are usually discovered and maintained by the Hello protocol.
n Hello—Protocol used by OSPF to establish and maintain neighbor
relationship.
n Designated router (DR) and backup designated router (BDR)—A router that is
elected by all other routers on the same LAN to represent all the routers. Each
network has a DR and BDR. These routers have special responsibilities that
are discussed later in later.
n Neighborship list —A listing of all the neighbors to which a router has
established bi-directional communication. Not every pair of neighboring
routers become adjacent.
n Link-state database, also known as a topological database—A list of link-state
entries of all other routers in the internetwork. It shows the internetwork
topology. All routers within an area have identical link-state databases. The
link-state database is pieced together from LSAs generated by routers
n Routing table—The routing table (also known as forwarding database)
generated when an algorithm is run on the link-state database. Each router’s
routing table is unique.

OSPF Topologies
OSPF can run over multi-access networks or over non-broadcast networks. The
topology of a network has an impact on how adjacencies are created. Following
are the different topologies found in OSPF and covered in later.
n Broadcast Multi-access networks—Networks supporting many (more than
two) attached routers, together with the capability to address a single physical
message to all of the attached routers (broadcast). An Ethernet segment is an
example of a broadcast network.
n Point-to-point networks—A network that joins a single pair of routers. A T1
dedicated serial line is an example of a point-to-point network.
n Non-broadcast Multi-access networks—Networks supporting many (more than
two) routers, but having no broadcast capability. Frame Relay and X.25 are
example of Non-Broadcast Multiaccess Networks (NBMA)
                                       [This is the part one ,welcome for next]