OSPF
-send hello packet to 224.0.0.5 ( All ospf router )
-link state data exchanged
-when database complete, SPF algorithm runs
-valid route enter the routing table
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OSPF hello package include * Must match
- Router ID
- Area ID *
- Address of origination interface
- Authentication information *
- Hello interval *
- Dead interval *
- Priority
- DR/BDR
- Neighbout Router
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OSPF networks
Point to point
- No DR/BDR needed. all update send to 224.0.0.5
Broadcast
- DR/BDR needed - updating routing and topoloty to 224.0.0.6
NBMA network
- No broadcast no bdr but use unicast to decide DR
Point to multipoint
-No DR/BDR and allow multicast
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OSPF AREA/Router Type/ LSA
Area 0 = backbone Area / Core for all other router to connect
Stub area = block route update from external router adverstisement
Totally stub area = block other area and external route adverstisement and only allow own network routing update
Internal Router = router inside area perform normal route
ABR = more then 2 interfae connect to different area and must connect back to area 0.it can be perform the summarization.
ASBR = interface connect to external route
LSA
Type 1 , 2 = Normal routing update to DR/BDR
Type 3 , 4 = Generate by ABR and summarization for the area network
totally stubby area not accept type 3,4,5
Type 5 = External Router generate by ASBR.
Stub will block type LSA type 5
Type 7 = generate by NSSA
