Wednesday, December 16, 2015

OSPF task #5. Fine tuning

 Topology:



Use configuration from task OSPF #4 as initial configuration for this task.

Requirements:

1. Configure routers R4 and R5, so no more than 10 external prefixes can be redistributed into OSPF, and warning log entry should be generated when 7 or more prefixes are redistributed.
2. Configure relevant routers such as OSPF Hello messages are not sent on link between R8 and R1, and periodic LSA refresh will not occure on this link.
3. Configure the link between R1 and R2, so link failure is detected as fast as possible, without using BFD.
4. Routers in area 0 should not be used to forward traffic for 5 minutes after router is reloaded.

Solution:

Highlight the text below to reveal the solution.

1. On R4 and R5, configure limitation for maximum number of redistributed prefixes allowed into OSPF. 

2. Configure link between R1 and R8 as demand circuit. Note that network type need to be changed to point-to-point in order to suppress Hello messages. 


3. Configure minimal (1 second) dead-interval on link between R1 and R2. 



R1:

!
router ospf 1
 router-id 10.0.1.1
 max-metric router-lsa on-startup 300
 area 2 stub no-summary
 network 10.0.18.1 0.0.0.0 area 2

 neighbor 10.0.13.3
!
interface Ethernet0/1
 ip address 10.0.12.1 255.255.255.0
 ip ospf network point-to-point
 ip ospf dead-interval minimal hello-multiplier 3
 ip ospf 1 area 0
!
!
interface Ethernet1/0
 ip address 10.0.18.1 255.255.255.0
 ip ospf network point-to-point
 ip ospf demand-circuit
!

R2:

!
router ospf 1
 router-id 10.0.2.2
 max-metric router-lsa on-startup 300
 area 3 nssa

 summary-address 10.0.67.0 255.255.255.0 not-advertise
!
interface Ethernet0/1
 ip address 10.0.12.2 255.255.255.0
 ip ospf network point-to-point
 ip ospf dead-interval minimal hello-multiplier 3
 ip ospf 1 area 0
!


R3:


!

router ospf 1
 summary-prefix 10.0.67.0/24 not-advertise
 max-metric router-lsa on-startup 300
 area 0
  interface GigabitEthernet0/0/0/0
   authentication message-digest
   message-digest-key 1 md5 encrypted 04683F34200F6B
   network non-broadcast
   neighbor 10.0.13.1
  !
  interface GigabitEthernet0/0/0/1
   authentication-key encrypted 13263B372A3E
   authentication
  !
 !
 area 3
  nssa
  interface GigabitEthernet0/0/0/2
  !
 !
!

R4:

!
router ospf 1
 area 3 nssa
 summary-address 10.0.66.0 255.255.254.0
 summary-address 10.0.67.0 255.255.255.0
 redistribute maximum-prefix 10 70
 redistribute eigrp 100 subnets route-map REDIST
!

R5:

!
router ospf 1
 maximum redistributed-prefixes 10 70
 redistribute eigrp 100 route-policy REDIST
 area 3
  nssa
  interface Loopback0
   network point-to-point
  !
  interface GigabitEthernet0/0/0/1
  !
  interface GigabitEthernet0/0/0/2
  !
 !
!

R8:

!
interface Ethernet0/0
 ip address 10.0.18.8 255.255.255.0
 ip ospf network point-to-point
 ip ospf demand-circuit
!

Verification:


R1# sh ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
10.0.2.2          0   FULL/  -        765 msec    10.0.12.2       Ethernet0/1
10.0.3.3          1   FULL/BDR        00:01:39    10.0.13.3       Ethernet0/0
10.0.8.8          0   FULL/  -           -        10.0.18.8       Ethernet1/0


R8#sh ip ospf neighbor



Neighbor ID     Pri   State           Dead Time   Address         Interface
10.0.1.1          0   FULL/  -           -        10.0.18.1       Ethernet0/0


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