Learning by practicing: Cisco CCNP - 300-101 - OSPF Configuration and Verification, Peeking into the raw packets

Sunday, January 11, 2015

Cisco CCNP - 300-101 - OSPF Configuration and Verification, Peeking into the raw packets

Cisco CCNP - 300-101 - OSPF Configuration and Verification while peeking into the raw packets

So it's that time again for me to renew my Cisco Certifications. As a result, this post is based on my preparation for the CCNP Route Exam (300-101).

In this post I will be focusing on OSPF Configuration and Verification while peeking into the raw packet

Topology
This topology consists of one 2 HQ and 2 Branches routers

HQ_DR-Area0_100:
    - Interface fa0/0 - connected to HQ_BDR-Area0_200 - IP 1.0.0.1/30 - Area 0
    - Interface fa1/0 - connected to BR-1_AREA100 - IP 1.0.0.5/30 - Area 100
    - Interface lo1 - Loopback for testing - IP 2.0.0.1/32 - Area 0


HQ_BDR-Area0_200
    - Interface fa0/0 - connected to HQ_DR-Area0_100 - IP 1.0.0.2/30 - Area 0
    - Interface fa1/0 - connected to HQ_DR-Area0_100 - IP 1.0.0.9/30 Area 200
    - Interface lo1 - Loopback for testing - IP 3.0.0.1/32 - Area 200


BR-1_AREA100
    - Interface fa0/0 - HQ_DR-Area0_100 - IP 1.0.0.6/30 - Area 100
    - Interface fa1/0 - connected to LAN - IP 192.168.0.1/24 - Area 100

    203 Server on BR-1_AREA100
        eth0 - 192.168.0.2/24
        Default Gateway - 192.168.0.1


BR-2_AREA200_300
    - Interface fa0/0 - connected to Internet - IP 1.0.0.10/30 - Area 200
    - Interface fa1/0 - connected to LAN - IP 172.16.0.1/24 - Area 300
    - Interface lo1 - 4.0.0.1/32 - Area 300

    Kali Host on BR-2_AREA200_300
        eth0 - 172.16.0.2/24
        Default Gateway - 172.16.0.1


Interface Configurations
HQ_DR-Area0_100:

HQ_BDR-Area0_200

BR-1_AREA100

BR-2_AREA200_300

OSPF Configuration
HQ_DR-Area0_100:

Above we see, the OSPF process 1
I've manually specified the "router-id" as "2.0.0.1"
I then declare the networks which should participate in this OSPF process

HQ_BDR-Area0_200

Above I've included the "virtual-link". A Virtual link is used because I have discontiguous areas. Every OSPF network must have Area 0 which is the backbone. Every other area must be connected to the backbone area. In cases where this is not so, you have to establish a virtual links
In this lab, area 300 is separated from area 0 by area 200. As a result, the virtual-link is needed.

BR-1_AREA100

BR-2_AREA200_300

Verification from HQ_DR-Area0_100
Above we see a brief view of the learned neighbors.
We know that this router is the Designated Router (DR)

Above we have a detailed view of the learned neighbors

Above the "show ip protocols" command gives us additional information from which we can validate if our OSPF configuration is working.Getting a complete view of the OSPF Database

Of course now we need to check the routing table to see what has been learnt

Looks like we have routes for both of the branch offices. The ultimate test is to ensure the two sites have full connectivity.

Ping looks good!

Traceroute looks better!!

Peeking at the raw OSPF Packets
In a previous post, I mentioned that OSPF used 5 packet types. In this post I will peek into some those packets
Hello Packet