new vrf with ospf as routing protocol

[laura_pineiro]

Hello,

I have four sites I will connect through an MPLS network. All the sites are using ICX 7450 routers. They don't have any vrf configured, so all the interfaces and static routing is done into the default-vrf.
I know I need at least a reboot in order to change the default values to give the space for the routing table in the new VRF. My question is:
Is service disruptive the VRF configuration (besides the reboot)?

I will configured an OSPF instance for this VRF, and I think that if I don't assign any interface L3 to the OSPF or the VRF, it shouldn't cause any troubles. Is that right?

Here's the configuration I'm planning to do (this is one of the routers)

!Configure VRF-related system-max values (default FastIron configuration does not allow space for VRF routing tables)!

system-max ip-route-vrf
reload

!Configure VRF instances

vrf new-vrf
exit-vrf

!Configure a Route Distinguisher (RD) for new VRF instance

vrf new-vrf
rd 1:91
ip router-id 172.25.131.6
exit-vrf

!Configure an IPv4 or IPv6 Address Family (AF) for new VRF instance

vrf new-vrf
address-family ipv4
exit-address-family
exit-vrf


!Configure routing protocols for new Multi-VRF instance

router ospf vrf new-vrf
area 0.0.0.0
log adjacency


!Assign VRF instances to Layer 3 interfaces
!NOTE: When a VRF instance is assigned to an interface, all IP addresses are deleted, and will trigger cache deletion, route deletion and associated cleanup. You must re-configure the IP address and interface properties after assigning a VRF instance to the L3 interface. 

interface loopback 2
vrf forwarding new-vrf
ip address 172.25.131.6/32
end

Do I missing something there?

Thanks in advance for your help!

[netwizz]

Awesome.  Yeah, that is probably for the best.  Generally speaking, I say keep it simple. Not saying saying to not use different OSPF areas, but the most common reason folks do that is to summarize.

Let's say your data-center site has 10.0.0.0/24, 10.0.1.0/24,  10.0.2.0/24, and 10.0.3.0/24.

You could summarize to /22 which would take those four /24 networks and present them as one /22.


Ordinary, it would announce itself to other areas and appear something like this:

TEST#show ip route 

     10.0.0.0/24 is subnetted, 4 subnets
O E2 10.0.2.0 [110/20] via 192.168.12.1, 00:00:20, GigabitEthernet0/0/0
O E2 10.0.3.0 [110/20] via 192.168.12.1, 00:00:21, GigabitEthernet0/0/0
O E2 10.0.0.0 [110/20] via 192.168.12.1, 00:00:22, GigabitEthernet0/0/0
O E2 10.0.1.0 [110/20] via 192.168.12.1, 00:00:24, GigabitEthernet0/0/0

Tell it to summarize to /22 by pasting something like this into the routing process:

summary-address 10.0.0.0 255.255.252.0

Results:

TEST#show ip route 

     10.0.0.0/22 is subnetted, 1 subnets
O E2 10.0.0.0 [110/20] via 192.168.12.1, 00:02:06, GigabitEthernet0/0/0

I hope that helps.  It would summarize between areas.  What is important is that you have an Area 0 as your backbone and every other area connects back to the backbone.  Hence if routing from Area 1 to Area 2, data would travel from Area 1 through Area 0 then to Area 2.  From there you would chop up "contiguous" subsets and assign them for use in each area to allow you to summarize.

In the above example, 10.0.4.0/24 would be listed as the next /22, but you would have to also add:

summary-address 10.0.4.0 255.255.252.0

Results:

TEST#show ip route 

     10.0.0.0/22 is subnetted, 2 subnets
O E2 10.0.0.0 [110/20] via 192.168.12.1, 00:02:06, GigabitEthernet0/0/0
O E2 10.0.4.0 [110/20] via 192.168.12.1, 00:01:01, GigabitEthernet0/0/0

However if you summarized to /21 you would be covered through 10.0.0.0 - 10.0.7.255...

Example:

summary-address 10.0.0.0 255.255.248.0

Results:

TEST#show ip route 

     10.0.0.0/21 is subnetted, 1 subnets
O E2 10.0.0.0 [110/20] via 192.168.12.1, 00:02:06, GigabitEthernet0/0/0

Hope this helps...  With four sites, I probably would not bother summarizing especially if the subnets are not contiguously assigned already unless you want to re-work your subnets.  IF you are assigning different areas, it is my sincere recommendation to keep contiguous subnets together for use in each area, so in the future if someone does want to summarize (i.e. as the network grows) it will be easy.  In the above example, you would not want 10.0.0.0/24 and 10.0.2.0/24 in one of your areas and 10.0.1.0/24 in another area.  Hope the above helps.