When I put "clear ip ospf process" after changing router-id on GNS3 , I got the bug that there was the output of "show ip ospf neighbor" but there was no ospf route . like following output after that , again I did put " clear ip ospf process "  without any changes after 2 minutes  . I could see the output of " sh ip route ospf " . Is this known bug on GNS3 ? Or Is this the known issue that it happens sometime on real Cisco routers ? I dont have the real labo . so I feel so insecure . Here is the output after did put " clear ip ospf process " R3#sh ip ospf nei Neighbor ID     Pri   State           Dead Time   Address         Interface 1.1.1.1           1   FULL/DR         00:01:42    172.16.100.1    Serial0/0     <------------------------------------- I can see the neighboring R3# R3#sh ip route ospf       <--------------------------------------------------there is no route . R3#clear ip ospf pro  <-------------------------again I put clear ip ospf process Reset ALL OSPF processes? [no]: y R3# *Mar  1 00:22:44.903: %OSPF-5-ADJCHG: Process 1, Nbr 1.1.1.1 on Serial0/0 from FULL to DOWN, Neighbor Down: Interface down or detached R3# *Mar  1 00:23:08.359: %OSPF-5-ADJCHG: Process 1, Nbr 1.1.1.1 on Serial0/0 from LOADING to FULL, Loading Done R3# R3#sh ip ospf nei Neighbor ID     Pri   State           Dead Time   Address         Interface 1.1.1.1           1   FULL/DR         00:01:50    172.16.100.1    Serial0/0 R3# R3#sh ip route ospf                                        <-------------------------------------This time I can see the output of sh ip route ospf      172.16.0.0/16 is variably subnetted, 10 subnets, 4 masks O       172.16.255.2/32 [110/65] via 172.16.100.2, 00:00:24, Serial0/0 O       172.16.255.1/32 [110/65] via 172.16.100.1, 00:00:24, Serial0/0 O IA    172.16.255.5/32 [110/75] via 172.16.100.2, 00:00:24, Serial0/0 O IA    172.16.255.4/32 [110/129] via 172.16.100.1, 00:00:24, Serial0/0 O IA    172.16.1.225/32 [110/129] via 172.16.100.1, 00:00:24, Serial0/0 O IA    172.16.1.193/32 [110/129] via 172.16.100.1, 00:00:24, Serial0/0 O IA    172.16.2.0/27 [110/74] via 172.16.100.2, 00:00:24, Serial0/0 O IA    172.16.1.124/30 [110/128] via 172.16.100.1, 00:00:24, Serial0/0 Have you ever have the issue on your real labo or actual environment　? ... View more

Why are loopbacks advertised as /32 host ? I have read following FAQ but I want to know the core reason for this. I mean why did cisco make it like this . Is this just the specification ? or Is there some reason for this ? ? http://www.cisco.com/en/US/tech/tk365/technologies_q_and_a_item09186a0080094704.shtml#qone Q. Why are loopbacks advertised as /32 host routes in OSPF? A. Loopbacks are considered host routes in OSPF, and they are advertised as /32. For more information, refer to section 9.1 of RFC 2328 . In Cisco IOS Software Releases 11.3T and 12.0, if the ip ospf network point-to-point command is configured under loopbacks, OSPF advertises the loopback subnet as the actual subnet configured on loopbacks. ISDN dialer interface advertises /32 subnet instead of its configured subnet mask. This is an expected behavior if ip ospf network point-to-multipoint is configured. For example, consider two routers (R1 and R2) connected via FastEthernet interface. R1 has the loopback configured with the ip ospf network point-to-point command and advertises the loopback in OSPF. interface Loopback0 ip address 1.1.1.1 255.255.255.0 ip ospf network point-to-point When checked in router R2 with the show ip route ospf command, the route 1.1.1.1 is seen as: !..output truncated 1.0.0.0/24 is subnetted, 1 subnets O       1.1.1.0 [110/11] via 10.1.1.1, 00:00:02, FastEthernet0/0 However, when the ip ospf network point-to-point command is removed from R1 to 0 interface, the route 1.1.1.1 on R2 is seen as: 1.0.0.0/32 is subnetted, 1 subnets O       1.1.1.1 [110/11] via 10.1.1.1, 00:00:01, FastEthernet0/0 ... View more

RA#debug ip ospf events 00:37:50: OSPF: Rcv pkt from 172.16.3.2, FastEthernet0/1, area 0.0.0.3 00:37:54 OSPF: Rcv hello from 192.168.2.1 area 0.0.0.1 from FastEthernet0/0 172.16.2.2  I want to know the meaning of these outcome . especially 00:37:54 OSPF: Rcv hello from 192.168.2.1 area 0.0.0.1 from FastEthernet0/0 172.16.2.2 RA received hello from 192.168.2.1 area 0 and what ?? also Is there any Documentation or URL which explain how to see all debug outcome ? for example , debug ip rip , debug ip packet debug ip ospf packet etc... I really need to figure out the outcome of these debug command . ... View more

I want to make sure my understanding is correct . so please help me out . I saw the logical topology attached the file name is logical topology . I wondered how the logical topology cange into physical topology . and I made the physical topology attached . Are both of topologys chart is the same  ? If i was wrong , Could you fix it ? Regards. ... View more