OSPF Priority Settings

[TOM FRANCHINA]

We are moving from decentralized routing to centralized. We have about 12 Cisco 3750 stacks with EMIs doing the routing for each stack.

We are now upgrading to Cisco 3850s and do not want to purchase EMIs for each stack. Instead we are going to us 2 Cisco 6509s for the routing.

I am having problems removing the EMIs without seeing a disruption in the network. We are a hospital and getting downtime is not always an option.

Is there a way I can get OSPF to prefer the 6509s. I know it is going against the concept of OSPF itself.... but these closets are less then 3 hops away from each other anyway.

Thanks,

Tom

[Kelvin Willacey]

Could you post a before and after? It's a bit hard to follow for me. My initial idea is to have a new process with an administrative distance lower than 110 but this may or may not work for you.

[JohnTylerPearce]

How is your current network topology. I know you have numerous 3750s, but are they access switches, connected to distribution switches, or are the 3750s access/distribution switches?

And there is always a way to prefer a route with OSPF, but as the previous poster mentioned, it would be great to have a before/after picture or some sort of idea.

[Joseph W. Doherty]

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

As the others posters have noted, we need something to better clarify what you're trying to do.

With OSPF, if you have redundant device L3 paths, it's often easy to push preferred paths about without any interruption to in-flight traffic.

What can be an issue, if you were doing routing on the edge stacks, gateways are likely there too, and they can't be moved without some interruption unless you've been using HSRP (unlikely on a stack).

[TOM FRANCHINA]

Well we are using HSRP and on switches. Hope this helps

[Kelvin Willacey]

What will the after look like?

[TOM FRANCHINA]

3750s will be replaced with 3850s. Fiber links will remain the same. No routing on the 3850s all routing will be done on the 2 - 6509s with HSRP for redundancy.

I can draw it if it would help

[Kelvin Willacey]

If I understand correctly then you are saying that a client's gateway is currently on your 3750 stack and you plan to disable OSPF routing on the 3750 stacks and migrate the gateways to the 6509 switches. If that's the case then down time is to be expected, but down time should not be that much as it will be only the time taken to disable OSPF and shutdown the gateway on the 3750 stack and enable it on the 6509, assuming the up links in place are trunked and not routed ports.

[Joseph W. Doherty]

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

As it appears you are using HSRP, and 6500s have a gateway, you should be able to just migrate the active gateways, set your stack OSPF to max cost (max-metric router-lsa), and then remove the stack's OSPF process.

[TOM FRANCHINA]

KWillacey

and JosephDoherty

I will max out the cost then remove the OSPF process.

Thank you all for your help!!!!!