Local VLAN lab question

Andy White · ‎06-25-2013

Hello,

I have been working on this lab over that last few hours. As you can see I am trying to use Cisco's Local VLAN model and use L3 in the Core and Distribution areas. I have put the SVIs on the Dist2 switch and all the PCs in separate VLANs can ping each other, also all PC and switches can ping all the P2P links. For some reason I couldn't use the /31 in PT which is a shame.

Anyway I'm a little stuck as the PC's gateways are the SVIs on the Dist 2 switch, so I was thinking how can I get round it if this switch fails or a link fails to it? I did disable the port on SW1 leading to Dist2 and see what the PC in VLAN 10 would do and it couldn't ping anyone anymore, I thought it would find another route, any suggestions? Should the Distribution switches be using GLBP? What should the cores be doing?

I will use my real switches once I have it correct on the sim, thanks in advance. I have added a diag and packet tracer file.

james.doukas · ‎06-25-2013

Can you run HSRP or VRRP in this SIM between DIST-1 and DIST-2? Not sure what this SIM can do. If DIST-2 is the only device hosting the first hop IP for the subnet(s) and it goes down, you're pretty much dead in the water. If SW1 is just vlan 10, and the links up to DIST-1 and DIST-2 are access (not dot1q trunks), then you could create another access connection between DIST-1 and DIST-2 on vlan 10 and have the two DIST devices do HSRP or VRRP. You would also need Spanning Tree to block the loop. There are several ways you could solve the issue but I'm not 100% sure of your overall plan. Also, its been awhile since I've used devices with Switched Virtual Interfaces so I can't remember if they can do the same thing as vlan interfaces.

glen.grant · ‎06-25-2013

Setup dist1 and dist2 using hsrp for your subnets.

Andy White · ‎06-26-2013

Thanks, I will give HSRP a try on my real kit as the sims don't do this, but is it better to use GLBP as the traffic would be load balanced?

Also what should the Cores be doing in all this as I have hardly touched them apart from the L3 P2P links and EIGRP statements.

Is it better to use a /31 between L3 switches too? The sim said it was a bad address, not tried on my real kit yet.

I just want to set up a core/dist/access local vlan topology in my lab as it is great for experience and help with my work and CCNP.

You comments are very appreciated.

Thanks

james.doukas · ‎06-26-2013

I don't use GLBP much simply because I like deterministic traffic flows. However, that's just my preference. Others will have a different view. I guess it depends on what your needs are.

There's not much you can do with the core as its just there to move traffic between distribution points. If you want, you could create some loopbacks and redistribute them into EIGRP just for practice. However, most core routers/switches should stay simple as they are designed to do one thing; move traffic as quickly as possible between distribution points.

You can use /31's if you want. I use both /30's and /31's but once again, its mostly preference. If you had hundreds of point to point connections and were restricted to a certain number of IP's, you could use /31's. However, with private IP address space and the ability to have, really, an unlimited number of IP's, its your choice.

Hope this is informative.