The Distributed Logical Router (DLR) in the VMware NSX platform provides an optimized and scalable way of handling East – West traffic within a data center. East – West traffic is the communication between workloads residing within the same data center, which is only increasing in modern data centers. In order to route between segments, traffic must be forwarded to a routing device, rather than directly to its destination. This non-optimal traffic flow is generally referred to as “hair pinning”.
The DLR component of the NSX platform prevents the “hair-pinning” by introducing an East – West routing element within the hypervisor kernel. Each host has a routing kernel module can perform routing between the segments its hosted virtual machines are connected to. The DLR is capable of advertising those connected networks to other routing devices by way of the OSPF and BGP dynamic routing protocols