OSPF Routing Protocol Configuration on Juniper Devices
OSPF Routing Protocol
OSPF has 3 types version
OSPv1, OSPv2,OSPv3
Routers running OSPF will usually use the destination IP Addresses 224.0..0.5 and 224.0.0.6 to send hello packets and LSAs onto the network segment
Uses shortest path
OSPF Framework
****Neighbors
Same subnet OSPF enabled routers
Adjacency formed using `HELLO` packet
***LSAs
Link state advertisements
Contains reachable subnet information
***LSDB
Link state database
Used to store subnet information
Important: OSPF has 3 database 1. LSDB , 2.Candidate db , 3,SPF db
OSPv2
OSPF support for classless IP addressing
Encrypted authentication allowed between neighbors
OSPv3
Ipv6 support
MOSPF disabled
OSPFv3 can still advertise IPv4 subnets
CALCULATING THE BEST PATH -
Use Dijkstra (SPF) algorithm for calculating
OSPF prefer to use the best network path
OSPF uses the SPF algorithm to find the lowest cost network path
OSPF Forming Adjacencies
***OSPF Packet types (5 TYPES) –
1-Hello
2-Database
3-Link state request
4-Link state updates
5-Link state acknowledgement
Important:Ospf Router id are 32 bit addreses
How to selecet OSPF Router ID ?
Highest IP Address of all active interfaces
Highest Ip address of all Loopback interfaces
Id specified under [router-options]
For change Route ID has to router reboot
Ospf -ERRORS
Incorrect subnet mask
Diffirent Timers
Area ID mismatch
Authentication information wrong -(Password mismatch , MTU Mismatches)
OSPF Adjaceny Procces
8 ssteps to Adjaceny
-Down
-Init
-Attempt
-2-way
-Exstart
-exchange
-Loading
-Full
BUILDING THE TOPOLOGY OSPF
OSPF has a mechanism whosch can reduce flooded traffic
Ospf calls the master router the designated router or DR
A backup router DR is also elected, this is known as the Backup Designated router or BRD
For to be Master:
Priority
Router id
Important: Highest Router id becomes the Designated Route (DR)
*Priorty degree lowest can be DR
*Highest Router Id and Priority can be BDR.
Important: if a new router is added with a higher priorty it will become DR OTHER category
MAIN LSA PACKET TYPES
Router
Network
Summary
OSPF AREAS
SUB SYSTEM = AREAS
Areas help reduce the size of the OSPF database
*********Ofspf has 6 area type
Backbone area=0
Normal area
Stub area
Totally stubby area
Not so totally stubby area
OSPF ROUTER TYPES
ABR (area border router)
ASBRD (Autonomos system border router)
Backbone router
Internal Router
OSPF CONFIGURATION
Example1: Backbone area