OSPF Flashcards
Link state topology that uses Dijkstra algorithm to compute routing information
OSPF
Collection of networks and routers that have the same area identification. The identifier is locally significant.
OSPF area
How is the OSPF router ID determined?
Configuration with router-id command Highest numbered IP address of loopback Highest numbered IP address of physical interface If no interface exists, set router ID to 0.0.0.0
Command that is used to manually set which router becomes the DR (Designated Router)
OSPF priority
When two or more routers are contending to be a DR on a network segment, how is the DR chosen?
Highest OSPF priority
Router type with an interface in area0
backbone
Router that connects two or more areas
Area Border Router (ABR)
Connects to additional routing domains; typically located in the backbone
AS Boundary Router (ASBR)
What is the default administrative distance of OSPF?
110
Routers receive these updates containing information about an OSPF area.
Link State Advertisements (LSA)
When routers receives LSAs from other OSPF routers, what database is populated?
Link State Database
What kind of route is populated into the routing table?
best path
Routers that reside on the same network link and exchange hello messages.
Neighbors
Neighbor routers that have exchanged Link State Updates (LSU) and Database Description (DD) packets.
Adjacencies
When forming an adjacency, what state do both routers begin in?
Init
R1 sends a Hello packet to R2. R2 does not see its own router ID and sends a Hello packet back. When R1 receives this packet and sees its own router ID, what state does R1 transition to?
2 way
What state is the DR and BDR selected in?
2 way
What state is the primary and designated router selected in?
ExStart
The actual exchange of database information happens in what state?
Exchange
The _____ router sends out database description packets to the _____ router and the secondary router sends an acknowledgment
primary secondary
What packet contains a list of the LSAs known to the router?
DD packet
If R1 sees that it is missing an LSA from the DD packet, what does it do?
Responds with a Link State Request (LS)
In what state does a router send LS for missing LSAs?
Loading state
Once all of the missing pieces of the puzzle are completed, both routers should have identical link state databases on these two routers. What is the state when an adjacency is formed?
Full state























