Wednesday, December 9, 2015

OSPF task #1. Single area OSPF.

Topology:


Routers R3 and R5 are running IOS-XR, the rest of the routers running IOS. 

Requirements: 


1.Configure connectivity between routers R1, R2 and R3 using OSPF.
2.Links between routers R1, R2 and R3, and loopback interfaces of R1, R2 and R3 should be in         OSPF area 0.
3.Link between routers R1 and R3, should be configured using standard based network type. R1 should be elected a DR on this link.
4.Link between routers R3 and R2 should be configured with Cisco proprietary network type, and R3 should be elected a DR on this link.
5.There should be no DR/BDR election on link between R1 and R2.
6.On link between R1 and R3, authenticate the adjacency using strongest possible authentication.
7.On link between R3 and R2, authenticate the adjacency using clear-text authentication.

Solution:

Highlight the text below to reveal the solution.

This is very basic configuration, but requires the understanding of OSPF network types. 
Standard based OSPF network types are NBMA and Point-to-multipoint. 
Cisco proprietary network types are Broadcast, Point-to-point and Point-to-multipoint. 
Link between R1 and R3 should be configured with NBMA network type, and R1 OSPF priority configured higher than R3 priority. Neighbors should be explicitly configured for NBMA networks. 
Link between R2 and R3 should be configured with Broadcast network type, and R3 OSPF priority configured higher that R2. 
Link between R1 to R2 can be any of the Point-to-point or Point-to-multipoint network types. 

R1: 


!
interface Ethernet0/0
 ip address 10.0.13.1 255.255.255.0
 ip ospf authentication message-digest
 ip ospf message-digest-key 1 md5 STRONG
 ip ospf network non-broadcast
 ip ospf priority 255
 ip ospf 1 area 0
!
interface Ethernet0/1
 ip address 10.0.12.1 255.255.255.0
 ip ospf network point-to-point
 ip ospf 1 area 0
!
interface Loopback0
 ip address 10.0.1.1 255.255.255.255
 ip ospf network point-to-point
 ip ospf 1 area 0
!
router ospf 1
 router-id 10.0.1.1
 neighbor 10.0.13.3
!

R2:

!
interface Ethernet0/0
 ip address 10.0.23.2 255.255.255.0
 ip ospf authentication
 ip ospf authentication-key CLEAR
 ip ospf network broadcast
 ip ospf priority 254
 ip ospf 1 area 0
!
interface Ethernet0/1
 ip address 10.0.12.2 255.255.255.0
 ip ospf network point-to-point
 ip ospf 1 area 0
!
interface Loopback0
 ip address 10.0.2.2 255.255.255.255
 ip ospf network point-to-point
 ip ospf 1 area 0
!
router ospf 1
 router-id 10.0.2.2
!

R3:

router ospf 1
 router-id 10.0.3.3
 area 0
  interface Loopback0
   network point-to-point
  !
  interface GigabitEthernet0/0/0/0
   authentication message-digest
   message-digest-key 1 md5 encrypted 122A31253D252B
   network non-broadcast
   priority 254
   neighbor 10.0.13.1
  !
  interface GigabitEthernet0/0/0/1
   authentication-key encrypted 0802606B282B
   authentication
   network broadcast
   priority 255
  !
 !
!

Verification:

R1#show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
10.0.2.2          0   FULL/  -        00:00:36    10.0.12.2       Ethernet0/1
10.0.3.3        254   FULL/BDR        00:01:49    10.0.13.3       Ethernet0/0

R1#sh ip ospf interface brief
Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C
Lo0          1     0               10.0.1.1/32        1     P2P   0/0
Et0/1        1     0               10.0.12.1/24       10    P2P   1/1
Et0/0        1     0               10.0.13.1/24       10    DR    1/1

R1#sh ip route ospf
Codes: L - local, C - connected, S - static, 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
       i - IS-IS, su - IS-IS summary, 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, H - NHRP, l - LISP
       + - replicated route, % - next hop override

Gateway of last resort is not set

      10.0.0.0/8 is variably subnetted, 8 subnets, 2 masks
O        10.0.2.2/32 [110/11] via 10.0.12.2, 02:00:31, Ethernet0/1
O        10.0.3.3/32 [110/11] via 10.0.13.3, 01:54:50, Ethernet0/0
O        10.0.23.0/24 [110/11] via 10.0.13.3, 01:54:50, Ethernet0/0


RP/0/0/CPU0:R3#show ospf neighbor
Wed Dec  9 15:05:56.069 UTC

* Indicates MADJ interface

Neighbors for OSPF 1

Neighbor ID     Pri   State           Dead Time   Address         Interface
10.0.1.1        255   FULL/DR         00:01:35    10.0.13.1       GigabitEthernet0/0/0/0
    Neighbor is up for 01:55:31
10.0.2.2        254   FULL/BDR        00:00:31    10.0.23.2       GigabitEthernet0/0/0/1
    Neighbor is up for 01:55:48

RP/0/0/CPU0:R3#show ospf interface brief
Wed Dec  9 15:06:00.169 UTC

* Indicates MADJ interface, (P) Indicates fast detect hold down state

Interfaces for OSPF 1

Interface          PID   Area            IP Address/Mask    Cost  State Nbrs F/C
Lo0                1     0               10.0.3.3/32        1     LOOP  0/0
Gi0/0/0/0          1     0               10.0.13.3/24       1     BDR   1/1
Gi0/0/0/1          1     0               10.0.23.3/24       1     DR    1/1

RP/0/0/CPU0:R3#show route ospf
Wed Dec  9 15:06:04.398 UTC

O    10.0.1.1/32 [110/2] via 10.0.13.1, 01:55:39, GigabitEthernet0/0/0/0
O    10.0.2.2/32 [110/2] via 10.0.23.2, 01:55:56, GigabitEthernet0/0/0/1
O    10.0.12.0/24 [110/11] via 10.0.23.2, 01:55:39, GigabitEthernet0/0/0/1
                  [110/11] via 10.0.13.1, 01:55:39, GigabitEthernet0/0/0/0

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