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Stacey Hummer
Beginner

Routing between cores and access switches

Looking for advice.  I am the only network guy in a small-medium sized business. Currently have OSPF running on all switches, including the access/edge switches. I have 3 core switches in a triangle design. Each of those feed the access switches in different locations. The access switches have desktops/access points and printers connected to them. IP addressing doesn't change once the switch is setup (each building has its own IP subnet). Each switch has a management IP on the loopback, each connection to the core switches is via layer 3. So at most there are maybe 5 different ip address schemes on each switch.

Each access switch has an OSPF next hop of the core switches layer 3 interface for that building. Each core switch has static routes for each building desktop ip address, loopback adapter and if a printer is present then the printer ip range. I’ve been trying to get the OSPF neighbor up but the only neighbor the cores see are each other. As well the static routes on some of the core switches are getting a little long and I’m worried I’m going to start causing issues.

I’m I overkilling the OSPF by having them on the access switches? Should I be using OSPF or should I simply be using RIP? Need some constructive input. Any help would be greatly appreciated.

4 REPLIES 4
balaji.bandi
VIP Expert

you have not mentioned what is the device models at the core and Access layer.

 

In general, OSPF is good to deploy, you do not need any Static Routes at all, all can be done Dynamic routing using IGP OSPF.

 

if you can like to make different Access switches in different Areas if this network big. 

 

here is a good guide to start :

 

https://www.ciscopress.com/articles/article.asp?p=2294214

 

https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/7039-1.html



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Richard Burts
Hall of Fame Guru

I am a bit confused. First you tell us that you have OSPF running on all switches, both core and access. Then you tell us that "I’ve been trying to get the OSPF neighbor up but the only neighbor the cores see are each other." So it appears that something is not right with running OSPF on access switches. But we have no details to help us understand what this problem would be. 

 

It might help to start by providing a simple diagram that shows the topology of the network. Then perhaps we might start with one core switch and one access switch connected to that core switch. Would you provide from each of the switches:

running config from the switch

output of the commands show ip ospf interface and show ip ospf neighbor and show cdp neighbor

HTH

Rick
Deepak Kumar
VIP Advocate

Hi,

Really, it's a bit confusing in the question. I don't know is your network working on OSPF or static routing? Are you migrating from Static routing to OSPF or vise versa? I have some questions to understand the issue as well as OSPF issues:

 

1. Are you using Point to Point Layer 3 links between Core switches to Access switches?

2. What is the OSPF configuration on Core and Access switches as well?

3. Have you changed the default MTU on any switches?

3. What is an output of "Show IP OSPF neighbor" and "Sho IP protocol" and "Sho IP OSPF interface"?

4. What is the purpose of the static route here?

5. Share your basic network diagram for a better understanding of the same. 

6. Any extra comment from your end.

 

Share the above details.

 

Regards,
Deepak Kumar,
Don't forget to vote and accept the solution if this comment will help you!
Joseph W. Doherty
Hall of Fame Expert

Like Balaji, if your L3 devices support OSPF, that should be find in lieu of RIP (especially RIPv1) and/or static routing.

Also like Rick and Deepak note, some additional information would help us help you as you should (normally) be able to run OSPF between all your L3 OSPF capable devices especially if there are direct connections between them.

Balaji also mentions the possibility of an OSPF multiple area design but that too is difficult to make a good suggestion about w/o additional information.
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