A long time ago I wrote a short article on what really went wrong with SDN, now a few years later the topic still pops up in a conversation with the great Ivan & he acknowledged my list of Tradeoffs (things to watch out for carefully) related to overlay networks and protocols which seems to be de-facto standard for most modern Network solutions that we see around in Enterprises & Telcos.
- Impact of overlay networks on visibility, reporting and performance management
- Additional control plane that would result in additional abstraction layers and interaction surfaces and hence cascading effect in many situations
- Impact on troubleshooting: how many solutions do we see in the market that can correlate underlay and overlay problems?
- When it comes to sizing equipment in terms of control plane or data plane, it poses a new level of complexity an architect would need to deal with and in most cases vendors themselves won’t be able to offer much help in general rather than just asking you to believe in their words
- I see lot of VXLAN and EVPN preachers, but let’s agree that mapping VLAN to VXLAN on 1:1 basis tells me you don’t know your stuff and believe too much in vendor marketing
- EBGP underlay with IBGP overlay…man we can do better
- Stitching two EVPN DCs with MPLS and SR: most of the implementations that I have seen were too complex and too fragile and thus results in a complex “policy.”
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