Tag Archives: cisco and juniper ospf

JunOS vs IOS – Basic OSPF

Let’s set up a basic OSPF adjacency between JunOS and IOS. I’ve got the following simple topology:

juniperospf JunOS vs IOS   Basic OSPF

The good thing here is that the configs shown will show the difference between JunOS and IOS as the actual configuration goal is the same for both.

The Cisco config is as follows:

Router>conf t
#int fa0
#ip address 192.168.1.2 255.255.255.0
#int lo100
#ip address 172.16.10.1 255.255.255.0

#router ospf 1
#network 192.168.1.0 0.0.0.255 area 0
#network 172.16.10.0 0.0.0.255 area 0
#exit

Now onto JunOS:

root@Olive>configure
# set interfaces em1 unit 0 family inet address 192.168.1.2/24
# set interfaces lo0 unit 100 family inet address 172.16.20.1/24

# edit protocols ospf area 0
# set interface 192.168.1.1
# set interface 172.16.20.1

Let’s see what we see on the Cisco:

Router#sh ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
172.16.20.1     128   FULL/BDR        00:00:34    192.168.1.1     FastEthernet0

Router#sh ip route

     172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
O       172.16.20.0/24 [110/1] via 192.168.1.1, 00:00:25, FastEthernet0
O       172.16.20.1/32 [110/1] via 192.168.1.1, 00:00:25, FastEthernet0
C       172.16.10.0/24 is directly connected, Loopback100
C    192.168.1.0/24 is directly connected, FastEthernet0

What about the Olive?

root@Olive> show ospf neighbor
Address         Interface   State           ID             Pri         Dead
192.168.1.2     em1.0       FULL            172.16.10.1    1           36

root@Olive>show route

172.16.10.1/32      *[OSPF/10]  00:09:05, metric 2
                     > to 192.168.1.2 via em1.0

And yes, both routers can ping both loopbacks :)