Migration-65xx to 6807 Core/Dist Switch – SVIs and Multi-Area OSPF

[JWP_69]

Hello,

I am migrating from a 6513 core/dist switch to a 6807XL.

The 6513 and 6807 are currently connected via a layer 2 port-channel  trunk link.  The SVIs and VLANs have been configured on the 6807, but are currently shutdown.  Static routes and ACLs have not been configured on the 6807.  I have successfully migrated all access layer switches and servers to the 6807.  The remaining tasks/caveats are:

-Turn up the SVIs on the 6807.

 -Shut down the SVIs on the 6513.

-Configure OSPF for all of the SVIs that are not VLAN 11 or 12.

-Configure OSPF to prefer non-vlan 11 & 12 paths.

-Remove trunk 6513 to 6807 trunk link.

-Shut down and remove 6513.

*Environment is too large/complex to use static routes.

*All sites are also separated by different VTP domains.

Multi area OSPF is configured in the current environment.  The issue I am having is with how OSPF is configured.  Area 0 at all four sites is 10.0.0.0/16 which is only VLAN 11 & 12.  Areas 1-4 are 10.0.0.0/8.  VLAN 11 & 12 are part of a “ring” network that is currently functioning as our backbone.  I have established L2 trunk links between all sites via dark fiber.  We want the traffic to prefer those links instead of the ring/backbone network.  There are four sites that currently have 65xx core/dist switches configured similarly as the site that I am currently migrating.  It is my understanding that I can’t have two OSPF areas configured to advertise the same VLANs.  How do I configure OSPF on the 6807 to advertise the same SVIs as the 6513 without having Area 1 configured the same on the 6807? How do I configure OSPF to prefer the dark fiber links instead of the ring/backbone.  The ring/backbone will remain, but only as a backup path.

The current configuration is:

Current Configuration of OSPF – VLAN 11 & 12 interfaces:

Site-A-6513 (Site that I am currently migrating)

OSPF:

router ospf 22

log-adjacency-changes

redistribute static subnets

network 10.0.0.0 0.0.255.255 area 0 

network 10.0.0.0 0.255.255.255 area 1

default-information originate

SVIs:

Site-A-6513#sh run int vlan 11

Building configuration...

Current configuration : 210 bytes

!

interface Vlan11

description Backbone

ip address 10.0.80.11 255.255.240.0

ip pim sparse-dense-mode

ip cgmp

ip ospf hello-interval 1

ip ospf priority 202

mls rp vtp-domain VTP1

mls rp ip

end

Site-A-6513#sh run int vlan 12

Building configuration...

Current configuration : 210 bytes

!

interface Vlan12

description Backbone

ip address 10.0.96.11 255.255.240.0

ip pim sparse-dense-mode

ip cgmp

ip ospf hello-interval 1

ip ospf priority 202

mls rp vtp-domain VTP1

mls rp ip

end

Site-B-6513 (currently in process of migrating to a temporarily trunked 6807):

OSPF:

router ospf 22

log-adjacency-changes

redistribute static subnets

passive-interface Vlan1

network 10.0.0.0 0.0.255.255 area 0

network 10.0.0.0 0.255.255.255 area 2

SVIs:

Site B VLANs 11 & 12:

Site-B-6513#sh run int vlan 11

Building configuration...

Current configuration : 207 bytes

!

interface Vlan11

description Backbone

ip address 10.0.80.21 255.255.240.0

ip pim sparse-dense-mode

ip cgmp

ip ospf hello-interval 1

ip ospf priority 101

mls rp vtp-domain M-VTP

mls rp ip

end

Site-B-6513#sh run int vlan 12

Building configuration...

Current configuration : 207 bytes

!

interface Vlan12

description Backbone

ip address 10.0.96.21 255.255.240.0

ip pim sparse-dense-mode

ip cgmp

ip ospf hello-interval 1

ip ospf priority 101

mls rp vtp-domain M-VTP

mls rp ip

end

Site-C-6807:

OSPF:

router ospf 22

redistribute static subnets

passive-interface Vlan1

network 10.0.0.0 0.0.255.255 area 0

network 10.0.0.0 0.255.255.255 area 3

SVIs:

Site-C-6807#sh run int vlan 11

Building configuration...

Current configuration : 169 bytes

!

interface Vlan11

description Backbone1

ip address 10.0.80.31 255.255.240.0

ip pim sparse-dense-mode

ip ospf hello-interval 1

ip ospf priority 101

mls rp ip

end

Site-C-6807#sh run int vlan 12

Building configuration...

Current configuration : 169 bytes

!

interface Vlan12

description Backbone2

ip address 10.0.96.31 255.255.240.0

ip pim sparse-dense-mode

ip ospf hello-interval 1

ip ospf priority 101

mls rp ip

end

Site-D-6509:

OSPF:

router ospf 22

log-adjacency-changes

redistribute static subnets

passive-interface Vlan1

network 10.0.0.0 0.0.255.255 area 0

network 10.250.0.5 0.0.0.0 area 0

network 10.0.0.0 0.255.255.255 area 4

SVIs:

Site-D-6509#sh run int vlan 11

Building configuration...

Current configuration : 206 bytes

!

interface Vlan11

description Backbone

ip address 10.0.80.41 255.255.240.0

ip pim sparse-dense-mode

ip cgmp

ip ospf hello-interval 1

ip ospf priority 101

mls rp vtp-domain G-VTP

mls rp ip

end

Site-D-6509#sh run int vlan 12

Building configuration...

Current configuration : 206 bytes

!

interface Vlan12

description Backbone

ip address 10.0.96.41 255.255.240.0

ip pim sparse-dense-mode

ip cgmp

ip ospf hello-interval 1

ip ospf priority 101

mls rp vtp-domain G-VTP

mls rp ip

end

 How can I migrate to the new switch with little to no network disruption?  Specifically, how can I configure OSPF on the 6807 without causing routing issues? 

Many thanks in advance for any suggestions.

[paul driver]

Hello

---

@JWP_69 wrote:  It is my understanding that I can’t have two OSPF areas configured to advertise the same VLANs.  How do I configure OSPF on the 6807 to advertise the same SVIs as the 6513 without having Area 1 configured the same on the 6807? How do I configure OSPF to prefer the dark fiber links instead of the ring/backbone.  The ring/backbone will remain, but only as a backup path.

---

At present it looks like vlan 11/12  area both in area 0 at each site and these are reachable via Site A which is your DR due to a default route its advertising?

Now if i understand this correctly you wish traffic for these vlans to go via a different path other than site A?

Could you post a topology of how the alternative path look like.?

[JWP_69]

Hi Paul,

You are correct.  There is a SVI/VLAN 11&12 at every routed site with different IPs within the same subnet for 11 and 12 respectively. I am attempting to (1) Migrate from 65xx switches to 6807 switches with minimal to no network disruption. (2)Modify the routing so that all traffic traverses newly established dark fiber links instead of the current "ring" network that is being decommissioned very soon.  There is a VLAN 11 and 12 are the only two SVIs that are being advertised at each site in area 0 (10.0.0.0/16).  All of the other SVIs are being advertised in area 1,2,3,4 (10.0.0.0/8) respectively. I have attached a pdf that shows the current and end state topology that should help clarify the issues. Please let me know if you have any additional questions.

[paul driver]

Hello

For the migration i would do similar to what you have already mentioned.

1)l L2 trunk between old- new core having the l3 svis on the new core already configured but in a down state
2) relocate the L2 interconnects keeping the routing on the old core
3) when ready arrange some down time, disconnect L2 trunk and relocate wan connection and enable the L3 svis, any static routes etc  then test

4) Backout would be disable routing on new core , reestablish L2 connection with old core and re- relocate wan connection back to old core.

Now after your migration I see your topology something like this:

Site 1
1 -2

1-3

1-4  ( via mce 6509)

Site 2
2 -1

2-4

Site 3
3 -1

3-4

Site 4
4 -1 ( via mce 6509)

4-2

4-3

Now all sites connect to other  vlan 11-12 through site 1,Whats vexing me is where are the dark fibre coming into play also your other networks you mention.

example
Lets say site 2 wants to reach site 3 for these other networks what is you expectation on how you would like them to communicate with each other if not via site 1