Using the same lab setup from EIGRP lab, I will configure OSPF with an single area of 51. OSPF can be very easy to configure or really difficult depending on the topology. First I will create an instance of OSPF using a process id of 1. The process ID is locally significant and doesn't need to match between neighbors.
Corp(config)#router ospf 1
Corp(config-router)#network 10.1.1.0 0.0.0.255 area 51
Corp(config-router)#network 10.1.2.0 0.0.0.3 area 51
Corp(config-router)#network 10.1.3.0 0.0.0.3 area 51
Corp(config-router)#network 10.1.4.0 0.0.0.3 area 51
Corp(config-router)#network 10.1.5.0 0.0.0.3 area 51
I created an instance of OSPF with a process id of 1 and added all my networks to area 51. The same will be done for the rest of Corp neighbors. Before I do that I will verified OSPF on Corp with a couple of commands.
Using show ip ospf , I can verified the RID , area information along with SPF information and LSA timers. The router id is 10.1.5.1, the highest IP address of an active interface, no loopback is set to take precedence.
Corp#show ip ospf
Routing Process "ospf 1" with ID 10.1.5.1
Supports only single TOS(TOS0) routes
Supports opaque LSA
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 0. Checksum Sum 0x000000
Number of opaque AS LSA 0. Checksum Sum 0x000000
Number of DCbitless external and opaque AS LSA 0
Number of DoNotAge external and opaque AS LSA 0
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
External flood list length 0
Area 51
Number of interfaces in this area is 5
Area has no authentication
SPF algorithm executed 4 times
Area ranges are
Number of LSA 1. Checksum Sum 0x001cd5
Number of opaque link LSA 0. Checksum Sum 0x000000
Number of DCbitless LSA 0
Number of indication LSA 0
Number of DoNotAge LSA 0
Flood list length 0
The next few commands will not show much information because I have not setup OSPF on the other routers. Using the database command I can see the RID and which advertising router sent it, itself in this case.
Corp#show ip ospf database
OSPF Router with ID (10.1.5.1) (Process ID 1)
Router Link States (Area 51)
Link ID ADV Router Age Seq# Checksum Link count
10.1.5.1 10.1.5.1 1793 0x80000006 0x00feff 5
I see nothing here because no other neighbors have been configured.
Corp#show ip ospf neighbor
Corp#
Looking at the ospf interface command, I can see process id, RID, network type (point-to-point) because it is a single serial interface connected to one other serial link. Point-to-point networks have no DR or BDR as I can confirmed here. Hello/Dead timers can be seen here, ptp networks has a different default hello timer (10) than Broadcast (30 )networks.
Corp#show ip ospf interface serial 0/0/0
Serial0/0/0 is up, line protocol is up
Internet address is 10.1.2.1/30, Area 51
Process ID 1, Router ID 10.1.5.1, Network Type POINT-TO-POINT, Cost: 64
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 00:00:08
Index 2/2, 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
Suppress hello for 0 neighbor(s)
With IP protocols you can determine the process ID, router ID, type of area, networks and areas configured for OSPF, and the OSPF Router IDs of neighbors.
Corp#show ip protocols
Routing Protocol is "ospf 1"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 10.1.5.1
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
10.1.1.0 0.0.0.255 area 51
10.1.2.0 0.0.0.3 area 51
10.1.3.0 0.0.0.3 area 51
10.1.4.0 0.0.0.3 area 51
10.1.5.0 0.0.0.3 area 51
Routing Information Sources:
Gateway Distance Last Update
10.1.5.1 110 00:14:35
Distance: (default is 110)
I will finish configuring and OSPF and see the results from a couple of show commands. Now we can
see all neighboring routers along with their RID and which router advertised it.
Corp#show ip ospf database
OSPF Router with ID (10.1.5.1) (Process ID 1)
Router Link States (Area 51)
Link ID ADV Router Age Seq# Checksum Link count
10.1.5.1 10.1.5.1 341 0x8000000c 0x00feff 8
192.168.20.1 192.168.20.1 493 0x80000007 0x00feff 6
192.168.40.1 192.168.40.1 385 0x80000005 0x00feff 4
172.16.10.1 172.16.10.1 337 0x80000004 0x00feff 2
Net Link States (Area 51)
Link ID ADV Router Age Seq# Checksum
10.1.5.1 10.1.5.1 341 0x80000002 0x005ce6
OSPF goes through an election process in broadcast and NBMA networks to find a DR and BDR. There are no DR or BDR in point-to-point networks. Using the show ip ospf interface command I can see that interface fe 0/0 (broadcast) has a DR 1.2.3.4 (Corp) and a BDR 3.3.3.3 (R3)
Corp#show ip ospf interface fastEthernet 0/0
FastEthernet0/0 is up, line protocol is up
Internet address is 10.1.5.1/30, Area 51
Process ID 1, Router ID 1.2.3.4, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State DR, Priority 1
Designated Router (ID) 1.2.3.4, Interface address 10.1.5.1
Backup Designated Router (ID) 3.3.3.3, Interface address 10.1.5.2
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:06
Index 4/4, 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 3.3.3.3 (Backup Designated Router)
Suppress hello for 0 neighbor(s)
No comments:
Post a Comment