OSPF-Open Shortest Path First

RFC 2328
area range 32 bit
notation by 1 or 0.0.0.1
LSA- link state advertisement
Multiaccess
- broadcast- DR BDR election
- non broadcast
use Dijkstra SPF algorithm

RID-Router ----->loopback IP----->highest phyisical IP

DR election
1. priority default 1 (0-255)
2. highest RID

BDR-Backup DR

Packets
- Hello
- DBD- brief description of LAS
- LSR
- LSU
- LSA

Condition for neighbor
MTU
area ID
subnet mask
Stub area flag
unique RID
Match authentication

Authentication three types
0=null
1=clear text
2=MD5

hello discover neighbor
Down- no ospf
attempt- hello sent not received
init- hello received
to-way- condition of neighbor is ok(DR/BDR election)
extart- Master/Slave based in RID
exchange- DBD
loading- LSR/LSU
full- complete database exchange

Network Type
Broadcast
- form DR/BDR, multicast 224.0.0.5-All SPF routers 224.0.0.6 All DR/BDR
- DR Other will be in Two-way state
Non Broadcast-DR/BDR
 - hello 30 sec

Point-To-Point- Hello 10sec
Point-To-MultiPoint- No DR/BDR election

Point-To-Point non-broadcast
loopback


LSA1- Router Link State
- generated by every router for each area connected
- full update 30 min
- keeps in database 60 min
Sequence No- 0x 80000001
age- value is maximum to withdraw the route
CRC- cycliy redudancy check
Link Count- only shown in case of LSA1, total no of link in that area

LSA2-Network Link State
- generated for every multiaccess segment
- Link ID- contains the IP of the DR router connected to that link

LSA3- Network Summary
- generated by ABR
- generate no of network that needs to advertised to other router
- originator -ABR
- Link ID- network that is carried
- going from one ares to another summarize the topology information

LSA4
- Contains the IP of ASBR

LSA5
- any route that is redistributed
- ASBR generates

LSA7
-NSSA

Path Selection
Cost= 100Mbps/link BW
Intera area(o)
Inter area (OIA)
External type1 (E1)
External type2 (E2)-Metric 20 default for redistribution
NSSA type 1 (N1)
NSSA type 2 (N2)

Stub area
- No LSA 5 also removes LSA 4
- ABR generate Inter-Area default routes LSA3

Totally Stub
- No LSA5,4 and 3

NSSA
- Removes LSA5,4 but allow LSA 7

Not So Totally stub area
- Removes LSA 5,4,3
- allows LSA 7
- ABR will originate inter-area default route

*Dec  1 06:35:33.107: OSPF-10 EVENT: Config: network 0.0.0.0 0.0.0.0 area 1

*Dec  1 06:35:33.107: OSPF-10 ADJ   Lo0: Interface going Down

*Dec  1 06:35:33.109: OSPF-10 ADJ   Lo0: 1.1.1.1 address 1.1.1.1 is dead, state DOWN

*Dec  1 06:35:33.109: OSPF-10 ADJ   Gi1: Interface going Down

*Dec  1 06:35:33.109: OSPF-10 ADJ   Gi1: 1.1.1.1 address 31.31.31.1 is dead, state DOWN

*Dec  1 06:35:33.109: OSPF-10 ADJ   Gi1: Neighbor change event

*Dec  1 06:35:33.109: OSPF-10 ADJ   Gi1: DR/BDR election

*Dec  1 06:35:33.109: OSPF-10 ADJ   Gi1: Elect BDR 0.0.0.0

*Dec  1 06:35:33.109: OSPF-10 ADJ   Gi1: Elect DR 0.0.0.0

*Dec  1 06:35:33.109: OSPF-10 ADJ   Gi1: Elect BDR 0.0.0.0

*Dec  1 06:35:33.109: OSPF-10 ADJ   Gi1: Elect DR 0.0.0.0

*Dec  1 06:35:33.109: OSPF-10 ADJ   Gi1: DR: none

*Dec  1 06:35:33.109: OSPF-10 ADJ   Gi1:    BDR: none

*Dec  1 06:35:33.109: OSPF-10 ADJ   Gi1: Flush network LSA immediately

*Dec  1 06:35:33.109: OSPF-10 ADJ   Gi1: Remember old DR 1.1.1.1 (id)

*Dec  1 06:35:33.109: OSPF-10 ADJ   Gi1: Interface going Up

*Dec  1 06:35:33.109: OSPF-10 PAK  : Gi1: OUT: 31.31.31.1->224.0.0.5: ver:2 type:1 len:44 rid:1.1.1.1 area:0.0.0.1 chksum:EA9B auth:0

*Dec  1 06:35:33.110: OSPF-10 ADJ   Lo0: Interface going Up

*Dec  1 06:35:33.110: %OSPF-6-AREACHG: 0.0.0.0/0 changed from area 0 to area 1

*Dec  1 06:35:33.116: OSPF-10 PAK  : Gi1:  IN: 31.31.31.3->31.31.31.1: ver:2 type:1 len:48 rid:3.3.3.3 area:0.0.0.1 chksum:A66F auth:0

*Dec  1 06:35:33.116: OSPF-10 ADJ   Gi1: 2 Way Communication to 3.3.3.3, state 2WAY

*Dec  1 06:35:33.116: OSPF-10 ADJ   Gi1: Backup seen event before WAIT timer

*Dec  1 06:35:33.116: OSPF-10 ADJ   Gi1: DR/BDR election

*Dec  1 06:35:33.116: OSPF-10 ADJ   Gi1: Elect BDR 1.1.1.1

*Dec  1 06:35:33.116: OSPF-10 ADJ   Gi1: Elect DR 3.3.3.3

*Dec  1 06:35:33.116: OSPF-10 ADJ   Gi1: Elect BDR 1.1.1.1

*Dec  1 06:35:33.116: OSPF-10 ADJ   Gi1: Elect DR 3.3.3.3

*Dec  1 06:35:33.116: OSPF-10 ADJ   Gi1: DR: 3.3.3.3 (Id)

*Dec  1 06:35:33.116: OSPF-10 ADJ   Gi1:    BDR: 1.1.1.1 (Id)

*Dec  1 06:35:33.116: OSPF-10 ADJ   Gi1: Nbr 3.3.3.3: Prepare dbase exchange

*Dec  1 06:35:33.116: OSPF-10 ADJ   Gi1: Send DBD to 3.3.3.3 seq 0xDC8 opt 0x52 flag 0x7 len 32

*Dec  1 06:35:33.116: OSPF-10 PAK  : Gi1: OUT: 31.31.31.1->31.31.31.3: ver:2 type:2 len:32 rid:1.1.1.1 area:0.0.0.1 chksum:962F auth:0

*Dec  1 06:35:33.116: OSPF-10 PAK  : Gi1: OUT: 31.31.31.1->31.31.31.3: ver:2 type:1 len:48 rid:1.1.1.1 area:0.0.0.1 chksum:684F auth:0

*Dec  1 06:35:33.122: OSPF-10 PAK  : Gi1:  IN: 31.31.31.3->31.31.31.1: ver:2 type:2 len:32 rid:3.3.3.3 area:0.0.0.1 chksum:923C auth:0

*Dec  1 06:35:33.177: OSPF-10 ADJ   Gi1: Rcv DBD from 3.3.3.3 seq 0xDB7 opt 0x52 flag 0x7 len 32  mtu 1500 state EXSTART

*Dec  1 06:35:33.177: OSPF-10 ADJ   Gi1: NBR Negotiation Done. We are the SLAVE

*Dec  1 06:35:33.177: OSPF-10 ADJ   Gi1: Nbr 3.3.3.3: Summary list built, size 0

*Dec  1 06:35:33.177: OSPF-10 ADJ   Gi1: Send DBD to 3.3.3.3 seq 0xDB7 opt 0x52 flag 0x0 len 32

*Dec  1 06:35:33.177: OSPF-10 PAK  : Gi1: OUT: 31.31.31.1->31.31.31.3: ver:2 type:2 len:32 rid:1.1.1.1 area:0.0.0.1 chksum:9647 auth:0

*Dec  1 06:35:33.185: OSPF-10 PAK  : Gi1:  IN: 31.31.31.3->31.31.31.1: ver:2 type:2 len:112 rid:3.3.3.3 area:0.0.0.1 chksum:DEB1 auth:0

*Dec  1 06:35:33.185: OSPF-10 ADJ   Gi1: Rcv DBD from 3.3.3.3 seq 0xDB8 opt 0x52 flag 0x1 len 112  mtu 1500 state EXCHANGE

*Dec  1 06:35:33.185: OSPF-10 ADJ   Gi1: Exchange Done with 3.3.3.3

*Dec  1 06:35:33.185: OSPF-10 ADJ   Gi1: Send LS REQ to 3.3.3.3 length 72

*Dec  1 06:35:33.185: OSPF-10 ADJ   Gi1: Send DBD to 3.3.3.3 seq 0xDB8 opt 0x52 flag 0x0 len 32

*Dec  1 06:35:33.185: OSPF-10 PAK  : Gi1: OUT: 31.31.31.1->31.31.31.3: ver:2 type:3 len:72 rid:1.1.1.1 area:0.0.0.1 chksum:BFC5 auth:0

*Dec  1 06:35:33.185: OSPF-10 PAK  : Gi1: OUT: 31.31.31.1->31.31.31.3: ver:2 type:2 len:32 rid:1.1.1.1 area:0.0.0.1 chksum:9646 auth:0

*Dec  1 06:35:33.191: OSPF-10 PAK  : Gi1:  IN: 31.31.31.3->31.31.31.1: ver:2 type:4 len:160 rid:3.3.3.3 area:0.0.0.1 chksum:FBDB auth:0

*Dec  1 06:35:33.191: OSPF-10 ADJ   Gi1: Rcv LS UPD from Nbr ID 3.3.3.3 length 160 LSA count 4

*Dec  1 06:35:33.192: OSPF-10 ADJ   Gi1: Synchronized with 3.3.3.3, state FULL

*Dec  1 06:35:33.192: %OSPF-5-ADJCHG: Process 10, Nbr 3.3.3.3 on GigabitEthernet1 from LOADING to FULL, Loading Done