Why Didn’t We Have Anycast Gateways Before VXLAN?
A while back I started thinking about why it took so long before we started using anycast gateways. I started thinking about what would be the reason(s) for not doing it earlier. I came up with some good reasons and it started making sense to me. I then asked you all what your thoughts were and received a ton of great responses. Here are a few that were mentioned:
- It was a natural evolution.
- More powerful devices.
- We didn’t have overlays.
- There were no protocols to map what device a MAC sits behind.
- Reusing the same IP would cause IP conflicts.
These are all certainly true to some degree. I would argue though that the main reason why we didn’t have it earlier is because of the topology and protocols we used in traditional LANs. The typical design was to have three layers, access, distribution, and core. The links in access to distribution layer were L2 only and the distribution layer had all the L3 configuration. A typical topology looked like this:

In a topology like this, there are only two devices that host the L3 configuration needed for hosts. When you have two of something, it’s natural to think Continue reading












