Network Types
- Broadcast
- Non Broadcast
- P2P
- P2MP
- P2MP NB
- Loop back
Network types and forming adjacencies
- OSPF Network Type does not need to match to form adjacency but they do need to be compatible
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other attributes must still match
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timers | stub flags
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What makes the network type compatible
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usage of type 2 LSA
- OSPF type 2 LSA Review
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LSA type 2 network LSA
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generated by the DR
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describe who is adjacent with DR
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not flooded outside the area they originate in
- Used to optimize OSPF operation on a shared segment
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reduce number of ospf adjacencies
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reduce LSA flooding replication
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simply spf calculation
- Network type compatibilities
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Network Type that use type 2 LSA
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broadcast
·
Non broadcast
- Network type that do not use type 2 LSA
·
point to point
·
point to multipoint
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point to multipoint non broadcast
- Broadcast
· Default on multi access broadcast medias
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ethernet
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token ring
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sends hellos and updates as multicast
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224.0.0.5 all SPF routers
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224.0.0.6 all DR routers
- DR/BDR OPERATION
- DR
- used on broadcast/non broadcast links
· forms adjacency with all routers on the link
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listens for LSUs on 224.0.0.6
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minimizes adjacencies
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minimizes LSA replication
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receives hellos, then sends updates on 224.0.0.5
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does not modify next hop value
- BDR
·
used for redundancy of DR
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does not re flood LSUs
- DRBrothers
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all other routers on the link
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not the DR or BDR
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Form full adjacencies with DR and BDR
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Stop at 2 way adjacency with each other
- DR/BDR chosen through election process
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DR/BDR election process
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election based on following priority
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0-255
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higher the better
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0 = never
· Router-id
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higher loopback/interface IP
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can be statically set
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higher better
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