Different vendors use different terms for this direct-return configuration. Nortel calls it Direct Server Return (DSR); F5 Networks calls it nPath; Foundry Networks, SwitchBack; and Radware, Out of Path. But don't let the terms throw you; they all mean when the server sends Web content directly to the client. In our Real-World Labs®, we use the term DSR when we review a content-aware device because it best describes the direct-return configuration.
DSR makes sense in cases where outbound traffic in the Web infrastructure is significantly heavier than inbound traffic. Eliminating that extra stop at the load balancer for outbound traffic can increase the throughput and response time of your Web infrastructure, a big plus when you're load balancing heavy content.
When outbound traffic isn't heavy, DSR may be unnecessary. There are about 10 outbound packets for every inbound packet in a typical Web infrastructure, so if you're handling 100 inbound packets per second, that's only 1,000 outbound packets per second. That's not enough to tax the load balancer or other content networking device, so DSR wouldn't be the best fit here.
Inline, one-arm and side-arm topologies are often used in conjunction with DSR so servers in the farm can bypass the content networking device and route directly to the client. Then you don't have to reconfigure servers in the farm when you install a load balancer.
Upon Closer Inspection
Bob Friday, Chief AI Officer for Juniper Networks, explains how the advanced technology is transforming operations.
Contact center leaders from 8x8, Awaken Intelligence, and 360insight discuss the importance of agent experience.
AI may force enterprises to rewire parts of their data centers so they are fully optimized to run such workloads. The question is do you use Ethernet or InfiniBand?
