Routing for VNIs That Have a HW-VTEP Binding
When an NSX logical switch is connected to a HW-VTEP using OVSDB, it cannot be attached to the Distributed Logical Router (DLR) at the same time. This limitation exists with all NSX implementations of this feature regardless of the hardware vendor providing the HW-VTEP functionality. Traditionally this meant that the default gateway for the VMs and bare-metal devices attached to the VNI/VLAN combination had be an external device. This device could be an Edge Services Gateway (ESG) VM attached to the VNI or a traditional router connected to the VLAN (or a physical firewall or another service device). These legacy options are depicted in the following figures.
With the Cloud-Scale ASICs available in the Cisco Nexus 9300-EX switches, it is now possible for the Cisco Nexus 9000 switches doing the OVSDB integration to also be the default gateway for the subnet being extended. This capability allows for CAPEX savings because an external physical router is no longer necessary. By providing the default gateway and routing capabilities using the switched virtual interface (SVI) feature, the Cisco Nexus 9000 switch can perform routing in the hardware while also providing OPEX savings. Redundancy can be achieved by using a first-hop redundancy protocol such as the Hot Standby Router Protocol (HSRP) or Virtual Router Redundancy Protocol (VRRP). This new capability is depicted in the following figure.