While we don’t have plans to seek an open solution in our DC we are considering ACI or VXLAN with EVPN. Our systems integrator partner expressed a view that VXLAN is still very new. Would you share that view?
Hardware: Nexus 9000 or Nexus 7x00/5x00? Honestly, I wouldn’t buy anything N7K-based these days, and assuming Nexus 9000 feature set fits my needs (they even have FCoE these days if you still care) the only consideration when choosing between N5K and N9K would be price-per-port.
Features: There are a few things missing on N9Ks like OTV or LISP. Maybe you don’t need them. I still don’t know why I’d need LISP and EVPN is not much worse than OTV (it does lack broadcast domain isolation features of OTV). Assuming you need OTV or LISP for whatever reason, it might be cheaper to buy an extra ASR than a Nexus 7K.
Stability: While I wouldn’t necessarily deploy ACI, I haven’t heard anything bad about N9K with VXLAN recently.
And now for the elephant in the room: L2 fabrics.
If you want to build a Cisco-based L2 fabric these days you have four design options (see also: standards):
- STP + MLAG (vPC). When was the last time you checked your calendar?
- FabricPath. While it’s elegant, it’s also clearly a dead-end technology. Every data center switching vendor (apart from Avaya) is rushing to board the VXLAN+EVPN train. Brocade, Cisco and Juniper have shipping implementations. Arista is supposedly talking about one. TRILL and SPBM are dying (in the data center), as are proprietary L2 fabrics (it was about time). I wouldn’t invest in one of those in 2016
- ACI. Maybe not. It’s a lot of hidden complexity, particularly if you need nothing more than a-bit-more-stable VLANs.
What’s left? VXLAN, in one of its three incarnations:
- Multicast-based. Why should you introduce IP multicast in your data center network just because someone tried to shift the problem around?
- Static ingress node replication. Perfect for small or fully-automated networks that need nothing more than L2 connectivity.
- EVPN. Ideal for people who believe virtual networking (including L2+L3 fabrics) should be done on ToR switches and not in the hypervisors.
So please don’t tell me not to go with VXLAN (particularly if you claim you need L2 fabric). There’s no real alternative.
Want to know more?
- Building Next-Generation Data Center online course is an intensive interactive deep dive into data center design challenges.
- Leaf-and-Spine Fabric Designs webinar covers common fabric designs, including L2, L3 and mixed L2+L3 fabrics.
- Data Center Fabrics webinar documents what the vendors are actually shipping (as opposed to promising).
- You can also ask me for a second opinion (well, not before early 2017).