Some background information:

Some of you may know that I work for a school district. Way way way back, maybe 5-6 years ago (maybe even longer than that) the local government body who was in charge of negotiating cable TV service contracts negotiated with Comcast that, in order for them to provide service in our area, they needed to provide fiber to local government and schools for FREE. So, we've been very happily benefiting from this since roughly 2007.

Well, as you can guess, this has come to an end. Come January 1st, 2012, we will need to pay for our fiber. Soo, we are working on plans to minimize the number of links we need to pay for. Our sites connect in an H pattern. Two sites connect to an aggregate switch, two sites connect to another aggregate switch, and the two aggregate switches connect to each other. The link the two aggregate switches use to connect to each other follows the same path as a link used by the city, and they are more than happy to share it with us. Here's current vs proposed network layout:



(The red "links" and white "switches" is the proposed physical setup, the other is our current physical setup)

The problem is figuring out how to share this link without having to severely change our network configurations. The plan was to use MPLS, but from what I'm told one of the switches the city uses doesn't have MPLS support.

The switch in question is a WS-C3560E-24TD-E with an IP Services version of IOS. At least, this is what I'm told. I haven't had a chance to look at it myself. I'm told that it DOES support VRF-Lite, but the sysadmin with the city is worried about using it for performance reasons (it doesn't do hardware based GRE).

We have 1GB links to our aggregate switches, and the link we would be sharing is a 10GB link (our aggregate switches would connect to city switches instead of directly connecting to each other).

We want the shared fiber to be as transparent as possible to our network so that we need to make minimal, if zero, changes.

I'm thinking VRF-Lite is our only option, but I'm weary of it because 1) we use the EIGRP routing protocol and the documentation I read says that it will still work, but they recommend using BGP, and 2) the same documentation states "A customer can use multiple VLANs as long as they do not overlap with those of other customers." We have 3 VLANs and may have more in the future and I dunno if we want to have to always coordinate this with the city.

Any thoughts or ideas?