exercise02

Exercise 02 - Configuring OSPF Routing

For this exercise we are going to configure OSPF routing using the eos_config module. We are going to put every interface into area 0.

Modify the template to add ospf

First we need to add the OSPF commands ip ospf area 0.0.0.0 and ip network point-to-point at the interface level. We can simply add these commands into our loop:

{% for interface in nodes[inventory_hostname] -%}
interface {{interface}}
{% if "Loopback" not in interface %}
    no switchport
    ip ospf network point-to-point
    ip ospf area 0.0.0.0
{% endif %}
    ip address {{nodes[inventory_hostname][interface]}}
{% endfor %}

We also need to enable ip routing, configure the OSPF process itself, the router-id, and advertise the Loopback address into OSPF. We want to use the loopback address as the router-id, but we need to remove the subnet (/32). We can do this a variety of ways, but one of the best ways is to take advantage of the ipaddr filter. There is documentation and a variety of examples but for our case we want to use ipaddr("address") which will cut off the subnet:

{{"172.16.0.1/32" | ipaddr("address")}}

would generate 172.16.0.1

Lets append the following to our template.

!
ip routing
!
router ospf 1
    router-id {{ nodes[inventory_hostname].Loopback1 | ipaddr("address") }}
    network {{nodes[inventory_hostname].Loopback1}} area 0.0.0.0

The full template is provided here: ospf.j2

Looking at the results

Use the show ip ospf neigh command to look for OSPF neighborship adjacencies

leaf01#show ip ospf neigh
Neighbor ID     VRF      Pri State                  Dead Time   Address         Interface
172.16.0.2      default  0   FULL                   00:00:30    172.16.200.17   Ethernet3
172.16.0.1      default  0   FULL                   00:00:29    172.16.200.1    Ethernet2

Check the route table with the show ip route command. There should be a route for 172.16.0.1, 172.16.0.2, 172.16.0.3 and 172.16.0.4 which represent the 4 devices:

leaf01#show ip route

VRF: default
Codes: C - connected, S - static, K - kernel,
       O - OSPF, IA - OSPF inter area, E1 - OSPF external type 1,
       E2 - OSPF external type 2, N1 - OSPF NSSA external type 1,
       N2 - OSPF NSSA external type2, B I - iBGP, B E - eBGP,
       R - RIP, I L1 - IS-IS level 1, I L2 - IS-IS level 2,
       O3 - OSPFv3, A B - BGP Aggregate, A O - OSPF Summary,
       NG - Nexthop Group Static Route, V - VXLAN Control Service,
       DH - Dhcp client installed default route

Gateway of last resort is not set

 C      10.0.2.0/24 is directly connected, Management1
 O      172.16.0.1/32 [110/20] via 172.16.200.1, Ethernet2
 O      172.16.0.2/32 [110/20] via 172.16.200.17, Ethernet3
 C      172.16.0.3/32 is directly connected, Loopback1
 O      172.16.0.4/32 [110/30] via 172.16.200.1, Ethernet2
                               via 172.16.200.17, Ethernet3
 C      172.16.200.0/30 is directly connected, Ethernet2
 O      172.16.200.4/30 [110/20] via 172.16.200.1, Ethernet2
 C      172.16.200.16/30 is directly connected, Ethernet3
 O      172.16.200.20/30 [110/20] via 172.16.200.17, Ethernet3
 C      192.168.0.0/24 is directly connected, Ethernet1

Complete

You have completed Exercise 02.

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