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Juniper QFX, IP-Fabric and VXLAN – Part 1

See the second part here: Juniper QFX, IP-Fabric and VXLAN – Part 2

Recently I have been lab testing and evaluating some Juniper QFX switches and new DC LAN architectures. In this and upcoming posts I will show some configuration guides and hints regarding Juniper QFX (5100-48Q and 5100-48S), IP-Fabric (complete L3 eBGP-fabric) and VXLAN configuration. Of course the fabric could use iBGP, OSPF or IS-IS if you wanted so, I just decided to go with eBGP due to some traffic engineering features. L3 Fabric poses some interesting questions and issues what we needn’t think in previous “old school” L2 networks.

  • Bare-metal server connectivity and L2 dual homing
  • Virtual-to-Virtual, Virtual-to-Physical, Physical-to-Physical
  • L2 overlay which is still needed (not only for vMotion)
  • Firewall, load balancer connectivity (talking about non-overlay, non-VXLAN, devices)
  • DCI

As you probably know the VXLAN is used as an overlay to bring L2 visibility over a routed L3 network using MAC-in-UDP encapsulation. This can be used for applications that require L2 connectivity. I’m not going to deep dive into how VXLAN works, but rather post some configuration snippets and guidelines with sample topologies. In case you need more detailed specifications regarding VXLAN, please check VMWare, Cisco, Cisco Live! and Juniper documentations, as these are really good resources, especially the Cisco Live! materials are worth checking out.

The test IP-fabric design is based on Spine-Leaf architecture with eBGP running in the core. There are two spine switches (QFX5100-24Q) and two leaf switches (QFX5100-48S). All leaf switches are connected to all spine switches. Routing protocol is eBGP over point-to-point links. All switches and leafs are running on their own AS number. L2 overlay is designed with VXLAN. In this design I’m introducing directly connected servers / appliances to the VXLAN network. In the Part 1, I will show the configuration of the IP-Fabric, we’ll dive into VXLAN in the next part. See physical and logical topologies below.

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