- Core to edge
- Edge to core
- Internet Edge-only
Prior to about a year ago most enterprises were doing gap analysis and planning for their internal deployment of IPv6 using either core-to-edge or edge-to-core designs. Use case and timeframe dictate which of these two options an enterprise pursues.
With the core-to-edge model, there usually is no defined use case or if there is it is pretty loosely defined. There is certainly not much in the way of a defined timeframe for deployment. The core-to-edge model allows for the deployment of IPv6 in the center or “core” of the network where the enterprise can gain valuable experience on stuff like routing, access control lists, addressing, and basic network management. All of this can be done with zero impact to the existing production IPv4 network. As the use case is more defined, as the time frame is more vetted out and as resource capabilities mature, the implementation moves towards the edges of the network such as the Campus access layers or the Data Center.
The edge-to-core model has traditionally been for the early adopters or vendors such as Microsoft or Cisco or Oracle where products that need to support IPv6 are being worked on by developers (as individuals or in labs) and those developers need access to build environments or hardware/software environments over an IPv6 transport. The edge-to-core model is nearly always dependent on an “overlay” model, which is basically tunneling of some sort (manually configured tunnels, ISATAP, MPLS, IPSec, etc…). As time goes on the underlying IPv4-only infrastructure is IPv6-enabled and the tunnels come down.
I have authored two Cisco Validated Designs (CVDs) that cover both the core-to-edge and edge-to-core designs for Campus and Branch networks. You can find those CVDs here:
The more active and, quite frankly, more interesting area of deployment has been facing the Internet. Enterprise customers from all over the world have been rapidly either adding IPv6 deployment in the Internet Edge to their existing effort or perhaps this is the ONLY place they are doing IPv6.
If you are currently planning for or have already designed your IPv6-enabled Internet Edge then check out my newly published CVD: