5. OSPF Terminology An interface on a router The status of a link between 2 routers A list of info about other routers in the network – shows the topology (also called Link-State database) A collection of network and routers that have the same area identification. Each router has same link-state info. A router in a area is called an internal router. OSPF Terminology Cost is the value assigned to the link, based on the bandwidth
8. OSPF Terminology Routing Table is generated when an algorithm is run on the link-state database. Each router’s table is unique to that router.
9. OSPF Terminology Adjacencies database is a listing of all the neighbors to which a router has established bi-directional communication
10. OSPF Terminology Designated router & backup designated router are routers that are elected by all other routers to represent all the routers. Every network has a DR & a BDR.
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16. OSPF Packet Types Acknowledges receipt of a neighbor’s LSA Type 5 – Link-state acknowledgement (LSAck) Transports LSAs to neighbor routers Type 4 – Link-state update (LSU) Requests specific pieces of a router’s LSD Type 3 – Link-state request (LSR) Describes contents of an OSPF router’s link-state database Type 2 – Database description packet (DBD) Estab. & main. Adjacency info w/ neighbors Type 1 – Hello Description OSPF Packet Type
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18. OSPF States After loading, routers now fully adjacent. Full Adjacency Link state updates exchanged Loading Routers send each other their databases Exchange Type 2 packets exchanged; master & slave estab. ExStart When a router sees itself in its neighbor’s hello packet Two-Way Hello packets are sent Init Everything down, nothing exchanged Down Definition State
19. OSPF Network Types Ethernet, Token-ring, FDDI PPP, HDLC Frame-Relay, X.25 No DR or BDR needed DR and BDR needed DR and BDR needed
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23. OSPF Configuration Process – ID – locally sig. – doesn’t have to be same on all routers Wildcard is necessary because OSPF supports VLSM & CIDR
24. Network Command and the Wildcard Mask S0 S0 fa0 fa0 RouterID: lo0 200.0.0.1/32 lo1 lo1 Merida Vargas 192.168.1.0/24 192.168.30.0/24 192.168.20.4.0/30 192.168.2.0/24 192.168.20.0/30 .1 .2 .5 Non-OSPF link .1 .1 .1 RouterID: lo0 201.0.0.1/32 Merida Merida(config)#router ospf 1 Merida(config-router)#network 192.168.1.0 0.0.0.255 area 0 Merida(config-router)#network 192.168.2.0 0.0.0.255 area 0 Merida(config-router)#network 192.168.20.0 0.0.0.3 area 0 Vargas Vargas(config)#router ospf 10 Vargas(config-router)#network 192.168.20.0 0.0.0.3 area 0 Vargas(config-router)#network 192.168.30.0 0.0.0.255 area 0 Only 192.168.20.0/30 NOT 192.168.20.4/30
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30. Default Route Example Entrance(config)# ip route 0.0.0.0 0.0.0.0 serial 0 Entrance(config)# router ospf 1 Entrance(config-router)# network 10.0.0.0 0.0.0.255 area 0 Entrance(config-router)# network 11.0.0.0 0.0.0.255 area 0 Entrance(config-router)# default-information originate ISP Entrance Engineering Marketing ip route 0.0.0.0/0 Static Route 0.0.0.0/0 0.0.0.0/0 Automatically Propagated s0 10.0.0.0/24 11.0.0.0/24 Engineering and Marketing will have 0.0.0.0/0 default routes forwarding packets to the Entrance router.
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32. show ip ospf Router#show ip ospf Routing Process "ospf 1" with ID 192.168.3.1 Supports only single TOS(TOS0) routes It is an area border router SPF schedule delay 5 secs, Hold time between two SPFs 10 secs Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs Number of external LSA 3. Checksum Sum 0x97E3 Number of DCbitless external LSA 0 Number of DoNotAge external LSA 0 Number of areas in this router is 2. 2 normal 0 stub 0 nssa External flood list length 0 Area BACKBONE(0) Number of interfaces in this area is 1 Area has no authentication SPF algorithm executed 8 times <text omitted> Area 1 <text omitted>
33. show ip ospf interface Router# show ip ospf interface Ethernet0 is up, line protocol is up Internet Address 206.202.2.1/24, Area 1 Process ID 1, Router ID 1.2.202.206, Network Type BROADCAST, Cost: 10 Transmit Delay is 1 sec, State BDR, Priority 1 Designated Router (ID) 2.2.202.206, Interface address 206.202.2.2 Backup Designated router (ID) 1.2.202.206, Interface address 206.202.2.1 Timer intervals configured , Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:00 Neighbor Count is 1, Adjacent neighbor count is 1 Adjacent with neighbor 2.2.202.206 (Designated Router) Suppress hello for 0 neighbor(s) Serial0 is up, line protocol is up Internet Address 206.202.1.2/24, Area 1 Process ID 1, Router ID 1.2.202.206, Network Type POINT_TO_POINT , Cost: 64 Transmit Delay is 1 sec, State POINT_TO_POINT, Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:04 Neighbor Count is 1, Adjacent neighbor count is 1 Adjacent with neighbor 2.0.202.206 Suppress hello for 0 neighbor(s) Timer intervals Router ID # Neighbor adjacencies
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