Flat Network to Routed

[casingnj2]

Hello,

I am currently in the planning stages of turning our FLAT network into a routed model for our remote sites. All of our remote sites currently connect back to our main office via fiber into our 6500e. The remote sites are small and only have a few switches at each site. My plan is to utilize 3850 switches connected via 10g fiber links back to our main office.

 My plan is to get two 3850 for redundancy onsite. I dont plan on stacking so they act independently. Due to this what would be the proper way to setup the layer 3 link? Bring a non switch interface to both switches utilzing VRRP from the 6500e? Trunk both switches together with redundant 10g fiber links?

One last item is I plan on using 2900 series routers to create a DMVPN for a backup link between the main site and remotes. I would hook the 2900 into the 3850s. This DMVPN would only be utilized should the fiber go down. EIGRP should be able to handle the cost associated between the 10G link and DMVPN? Im assuming I would need three interfaces on the router ( internet, switch1, switch 2) ??

Thank You

[Jon Marshall]

Not sure I entirely follow.

Why not stack the 3850s ?

How many links to the 6500 from each site ?

Does each site use internet locally or via main site ?

Jon

[casingnj2]

I have two reasons for not stacking the 3850.  One reason is I expereienced with another vendor a failed switch where the entire stack had to be rebooted.  My other reason is during an IOS upgrade the entire stack has to be rebooted and taken down, right?

I plan on doing two routed links from the 6500e.  One going into each 3850 onsite.  I also have the ability to link each site with fiber.  To further increase redundancy I should likely route each site to one another?

Each site gets internet from the main site.

If there is anything else you dont follow kindly ask.  I can draw a quick sketch if that would be helpful

Thank You

[Jon Marshall]

Thanks for explaining.

So when you say independantly will they be connected via trunk to run HSRP etc. for clients ?

I am just a bit confused about the VRRP with the 6500 you mentioned.

If you are using L3 routed links and EIGRP then just use equal cost paths.

In terms of internet you obviously need a default route from the main site. This means your 2900 DMPVN router has it's own default route but you have to make sure it doesn't pass this back to the 3850s although you presumably are going to be running EIGRP across the tunnel and peering with the 3850s ?

Am I generally following what you were thinking ?

Jon

[casingnj2]

I might be using the term VRRP incorrectly.  I used it previously with HP to have two core switches where one can failover and assume the gateway.

The 6500's would be a L3 routed link to the 3850s.  If Im going to use two 3850's at each site for redundancy would I utilize HSRP on the 3850s?  What would I need to setup redundancy on the 6500e going to these 3850s?

As for the DMVPN I was going to utilize a local ISP like patriot media  which is not the same ISP as the main site.  I plan on using EIGRP over our 10.x.x.x internal ips.  For the DMVPN on the 3850 cant I set the port to a higher cost?  So if the fiber fails it will go via DMVPN?

I believe you are following this.

[Jon Marshall]

Are you connecting your 3850s together and do you have access switches connecting to them with clients

If the clients connect directly to the 3850s no point in HSRP ie. if the switch fails the clients connected to the switch have no connectivity but if using access switch then depends on how you interconnect 3850s.

I was only thinking of HSRP as client side ie. between the 6500 and the 3850s just use routed links and exchange routes.

The 6500 should see equal cost paths to all subnets in the remote site and each 3850 will have it's own routes via the 6500.

Unless you want to influence which link is used.

Would need more details of how you see that part working.

DMVPN thing yes, simply set a higher cost although you should fine the EIGRP routes being received over the direct links have better metrics than those via the 2900.

Jon

[casingnj2]

I plan on connecting the 3850s together, should I not?  Clients will connect to the 3850 and access switches such as 2960 will be connected to the 3850.  

Thanks for clarifying HSRP

With the 3850s and dual links from the 6500 I was more thinking that one link will be hot and another a standby, should I not do it this way?

[Jon Marshall · Accepted solution]

Yes by all means connect the 3850s, I was just checking.

In terms of the links up to you how you do it.

You can use delay with EIGRP to influence which is used if that is what you want.

Like I say you could use both links outbound from the remote site by balancing your HSRP VIPs across both switches and inbound would use both links anyway because the 6500 sees equal cost paths.

It could mean traffic goes out on one link and comes back on the other but this won't be an issue as long as there are no stateful devices in the path like firewalls which it doesn't sound like there are.

There are so many different ways to do it with design but whatever you do in terms of HSRP, link usage I would definitely recommend running a routing routing protocol between the sites as you automatically know if the link(s) are down because you no longer recceive any routes.

Jon