Keith Bromley
Sr. Manager, Product Marketing at Ixia

Load Balancing: The ABCs of Network Visibility

October 25, 2017 by Keith Bromley

In today’s 24x7, “always on” world, the company’s data network must be as reliable as possible. Otherwise, revenue reduction and productivity losses are not only possible, but probable. This includes inline security and monitoring tools which can become a single point of failure. Load balancing provides a cost-effective alternative to full component redundancy.

What Is Load Balancing?

Load balancing is the ability for a network packet broker (NPB) to take incoming traffic and dynamically spread that traffic across multiple output ports. The NPB has the ability to split the traffic by bandwidth. For instance, incoming traffic at 40 Gbps could be distributed to either one 40 Gbps device, two 20 Gbps device, four 10 Gbps device, or some other combination of devices to process the required data. This functionality has a couple fundamental use cases including n+1 survivability and the ability to increase tool utilization.

Typical Use Cases

Here are some specific situations in which load balancing is particularly useful.

  • Inline n+1 survivability – Load balancing can be used by an NPB to spread traffic load across multiple inline security and monitoring tools. If the load is dimensioned correctly, should one of the tools fail, the remaining load can be spread across the remaining tools. For instance, a 40 Gbps load can be spread across five 10 Gbps tools. As shown below, if one of the tools goes down, the other four tools can still handle the loadtheir data rate simply increases from 8 Gbps each to 10 Gbps.



  • Out-of-band n+1 survivability – This capability is the same as the inline example above except that the tools are out-of-band.
  • Media Speed Reduction – Data coming into the packet broker can be broken down into lower rate streams of data and then sent to the proper monitoring devices. For instance, load balancing of 40 GE data allows you to spread the monitoring traffic across multiple 10 GE tools. Note, this obviously assumes you have enough 10 GE devices for the load. Once you implement this functionality, you can extend the life of those devices a little longer until you have enough budget to purchase more expensive tools that can handle the higher data rates.
  • Increase tool utilization – Individual tool processing can be optimized by consolidating tools into fewer locations. Centralization and load balancing allows you to pool your tools to increase device utilization versus having to deploy more tools across the network than really needed (using less capacity per tool) simply because of the architectural design.


The following are some things to keep in mind about NPB-based load balancing:

Architecture deployment – If you plan to deploy the capability inline, you will need bypass taps and you will want equipment that supports heartbeat messages for superior survivability capabilities.

Ease of use – You want the configuration of the load balancing capability to be as easy as possible. This means purchasing a solution with a GUI interface with drag and drop capabilities.

Dimensioning – Make sure you dimension the data loads to your tools correctly. You’ll want to have the normal bandwidth reservation for data bursts but then also enough bandwidth reserved for tool failure survivability.

More Information on Packet Captures

Further information about load balancing can be found here. More information about Ixia network performance, network security and network visibility solutions and how they can help generate the insight needed for your businness is available on the Ixia website.