Lab 16 - OSPF NSSA Area LSA7-to-5 Translation

Lab 16 - OSPF NSSA Area LSA7-to-5 Translation
Di Posting Oleh : Simple Learning
Kategori : Core Technologies OSPF Routing

Prerequisites: CCNP level skills.

Note!
Use topology  Lab 6. OSPF should be enabled on all interfaces with the most specific wildcard mask.

Topology

Pic. 1 - OSPF Multi-Area Topology.

Icons designed by: Andrzej Szoblik - http://www.newo.pl

Task List

Task 1
On R3 create a loopback interface with IP address 192.168.3.3/24. Redistribute it into OSPF as external E2 prefix.

Task 2
On R4 advertise a network 192.168.4.0/24 as external E2 prefixes. Do not create loopback interfaces to accomplish that. Area 1 must not accept LSA type 5. R4 must be able to ping 192.168.3.3. 

Task 3

Make sure that R1 is the translator of LSA7-to-5 and not R2. 

Task4
On R4 test connectivity to 192.168.3.3.

Lab Solution

Task 1

On R3 create a loopback interface with IP address 192.168.3.3/24. Redistribute it into OSPF as external E2 prefix. 

R3 Configuration:

!

interface Loopback2
 ip address 192.168.3.3 255.255.255.0
!

router ospf 1
 router-id 3.3.3.3
 log-adjacency-changes
 redistribute connected subnets
 network 10.1.13.3 0.0.0.0 area 0
 network 10.1.23.3 0.0.0.0 area 0
 network 172.16.103.3 0.0.0.0 area 0
 network 172.16.133.3 0.0.0.0 area 0  
!

Verification:

Pic. 2 - R1 Receives 192.168.3.0/24

Task 2
On R4 advertise a network 192.168.4.0/24 as external E2 prefixes. Do not create loopback interfaces to accomplish that. Area 1 must not accept LSA type 5. R4 must be able to ping 192.168.3.3.  

R4 Configuration:

!

ip route 192.168.4.0 255.255.255.0 Null0

!

router ospf 1
 router-id 4.4.4.4
 log-adjacency-changes
 area 1 nssa
 redistribute static subnets
 network 10.1.124.4 0.0.0.0 area 1
 network 172.16.104.4 0.0.0.0 area 1
 network 172.16.144.4 0.0.0.0 area 1

!

R1 Configuration:

!

router ospf 1
 router-id 1.1.1.1
 log-adjacency-changes
 area 1 nssa default-information-originate
 network 10.1.13.1 0.0.0.0 area 0
 network 10.1.124.1 0.0.0.0 area 1
 network 172.16.101.1 0.0.0.0 area 0

!

R2 Configuration:

!

router ospf 1
 router-id 2.2.2.2
 log-adjacency-changes
 area 1 nssa default-information-originate
 network 10.1.23.2 0.0.0.0 area 0
 network 10.1.124.2 0.0.0.0 area 1
 network 172.16.102.2 0.0.0.0 area 0

!

Verification:

Pic. 3 - Area 0 Receives 192.168.4.0/24.

Pic. 4 - Area 1 Receives the Default Route to External Networks.

Note!
ABRs in NSSA area do NOT inject the default route. That's why both R1 and R2 have been configured with 'area 1 nssa default-information-originate' command. 

Task 3
Make sure that R1 is the translator of LSA7-to-5 and not R2. 

R1 Configuration:

!

router ospf 1
 router-id 10.10.10.10

!

Note!
Changing the Router ID in situation the router has already established neighbor adjacency requires the clearing of ip ospf process.

Verification:

Pic. 5 - R1 is the LSA7-to-5 Translator.

Pic. 6- R2 Receives 192.168.4.0/24 from the LSA7-to-5 Translator (R1).

Pic. 7 - R1 OSPF Database.

 

Note!

If two ABRs are connected to NSSA area, the one with the HIGHEST Router ID becomes the translator of LSA7-to-5. That's why I needed to change the Router ID on R1 so it's higher than R2's. 

Task 4

On R4 test connectivity to 192.168.3.3.

Pic. 8 - R4 Reaches 192.168.3.3

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