[bs_icon name=”glyphicon glyphicon-chevron-right”] hint : make sure you type Show ip int brief before you advertise it

—————–here I go to R1—-

[bs_icon name=”glyphicon glyphicon-chevron-right”] hint:make sure you adverstsie it with correct WILD cards

/30 wild cards is 0.0.0.3
/24 wild cards is 0.0.0.255

[bs_icon name=”glyphicon glyphicon-chevron-right”] hint : when you do OSPF advertisment ; you must use correct subnet ID

that is for R1 f0/0 subnet ID= 10.10.10.0
R1 s0/0 subnet ID = 20.20.20.4
—————–here is my R1 configuration
R1#config t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router ospf 110
R1(config-router)#network 20.20.20.4 0.0.0.3 area 0
R1(config-router)#network 10.10.10.0 0.0.0.255 area 0
R1(config-router)#network 1.1.1.0 0.0.0.255 area 0
R1(config-router)#
————-here is my show run on R1———-
R1#show run

router ospf 110
log-adjacency-changes
network 20.20.20.4 0.0.0.3 area 0
network 10.10.10.0 0.0.0.255 area 0
network 1.1.1.0 0.0.0.255 area 0
——————-now I will go to R2#———-

[bs_icon name=”glyphicon glyphicon-chevron-right”] hint : make sure you type SHOW ip int brief ; so you can see what u have

R2#show ip int brief
Interface                 IP-Address      OK?     Method      Status                          Protocol

FastEthernet0/0     30.30.30.100    YES     manual        up                                   up
FastEthernet0/1      unassigned     YES       unset         administratively down       down
Serial0/0                 20.20.20.6      YES     manual        up                                   up
Loopback0              2.2.2.2           YES      manual       up                                   up

R2#config t
Enter configuration commands, one per line. End with CNTL/Z.
R2(config)#router os
R2(config)#router ospf 110
R2(config-router)#network 30.30.30.0 0.0.0.255 area 0
R2(config-router)#network 2.2.2.0 0.0.0.255 area 0
R2(config-router)#network 20.20.20.4 0.0.0.3 area 0
R2(config-router)#
00:22:11: %OSPF-5-ADJCHG: Process 110, Nbr 1.1.1.1 on Serial0/0 from LOADING to FULL, Loading Done

——————-as we see as soon as I advertised the S0/0 I see some action—————-
lets look at show run on R2#
router ospf 110
log-adjacency-changes
network 30.30.30.0 0.0.0.255 area 0
network 2.2.2.0 0.0.0.255 area 0
network 20.20.20.4 0.0.0.3 area 0

—————————now lets look at show ip ospf neighbors

R2#show ip ospf neighbor

Neighbor ID       Pri State     Dead Time       Address        Interface
1.1.1.1 0           FULL/ –      00:00:32           20.20.20.5      Serial0/0
R2#

———————-as we see remember ONLY we have DR/BDR on LAN segments 

lets look at another show command :
R2#show ip ospf int
FastEthernet0/0 is up, line protocol is up
Internet address is 30.30.30.100/24, Area 0
Process ID 110, Router ID 2.2.2.2, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State DR, Priority 1
Designated Router (ID) 2.2.2.2, Interface address 30.30.30.100
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:05
Index 1/1, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 0, Adjacent neighbor count is 0
Suppress hello for 0 neighbor(s)
Loopback0 is up, line protocol is up
Internet address is 2.2.2.2/24, Area 0
Process ID 110, Router ID 2.2.2.2, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Serial0/0 is up, line protocol is up
Internet address is 20.20.20.6/30, Area 0
Process ID 110, Router ID 2.2.2.2, Network Type POINT-TO-POINT, Cost: 781
Transmit Delay is 1 sec, State POINT-TO-POINT, Priority 0
No designated router on this network
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:03
Index 3/3, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1 , Adjacent neighbor count is 1
Adjacent with neighbor 1.1.1.1
Suppress hello for 0 neighbor(s)

——————-as we see when I type show ip ospf Int ; it will give me all interface

As I see Int f0/0 – called broadcast ( i can see DR)
int s0/0 -called Point-to-point ( no mention of DR/BDR)

————————-lets look at R2#show ip route

R2#show ip route
Codes: C – connected, S – static, I – IGRP, R – RIP, M – mobile, B – BGP
D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
E1 – OSPF external type 1, E2 – OSPF external type 2, E – EGP
i – IS-IS, L1 – IS-IS level-1, L2 – IS-IS level-2, ia – IS-IS inter area
* – candidate default, U – per-user static route, o – ODR
P – periodic downloaded static route

Gateway of last resort is not set

1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1 [110/782] via 20.20.20.5, 00:05:12, Serial0/0
2.0.0.0/24 is subnetted, 1 subnets
C 2.2.2.0 is directly connected, Loopback0
10.0.0.0/24 is subnetted, 1 subnets
O 10.10.10.0 [110/782] via 20.20.20.5, 00:05:12, Serial0/0
20.0.0.0/30 is subnetted, 1 subnets
C 20.20.20.4 is directly connected, Serial0/0
30.0.0.0/24 is subnetted, 1 subnets
C 30.30.30.0 is directly connected, FastEthernet0/0

——————now I should be able to ping from PC1 to PC6