WAN Routing in Data Centers with Layer-2 DCI

A while ago I got an interesting question:

Let's say that due to circumstances outside of your control, you must have stretched data center subnets... What is the best method to get these subnets into OSPF? Should they share a common area at each data center or should each data center utilize a separate area for the same subnet?

Assuming someone hasn’t sprinkled the application willy-nilly across the two data centers, it’s best if the data center edge routers advertise subnets used by the applications as type-2 external routes, ensuring one data center is always the primary entry point for a specific subnet. Getting the same results with BGP routing in Internet is a much tougher challenge.

3 comments:

  1. Replies
    1. Doesn't help much unless you have your own dark fiber (or lambdas, I guess) ... and it definitely won't save the day if you lose all paths in the DCI link.

      Delete
    2. Carrier Ethernet should be available in most first world countries?

      Delete

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Ivan Pepelnjak, CCIE#1354, is the chief technology advisor for NIL Data Communications. He has been designing and implementing large-scale data communications networks as well as teaching and writing books about advanced technologies since 1990. See his full profile, contact him or follow @ioshints on Twitter.