ThousandEyes, a company that does network monitoring, says software-defined wide-area networking (SD-WAN) is making visibility more difficult, so it has created agent-to-agent tests to make it easier to pinpoint issues in both the forward and reverse paths.

SD-WAN is becoming a popular technology for organizations looking to manage multiple Internet connections, but “it’s introducing new variability in routing,” says Nick Kephart, senior director of product marketing at ThousandEyes. “Now, if you need to troubleshoot, you need a more detailed perspective.”

Prior to SD-WAN, a typical WAN connection might be a single leaf from one provider. But with SD-WAN, traffic can move through different networks in each direction.

“Rather than one known circuit, you have multiple circuits with different providers and with different directions,” says Kephart.

While traffic asymmetry is nothing new, it’s becoming more frequent with the adoption of SDN in general and SD-WAN more specifically.

Kephart says typically, packets are monitored in a single direction, but ThousandEyes’ agent-to-agent tests provide bidirectional path visibility to automatically map both forward and reverse paths between endpoints.

The company places virtual probes across networks to simulate traffic and measure performance. Clients can install the probes in data centers or branch offices.

“A lot of monitoring in the WAN environment is device specific,” says Kephart, “but often you don’t get the context of flows of data.”

If there’s a network problem, businesses (or SD-WAN providers) need to know where the problem is occurring – whether it’s in a service provider’s network they have a relationship with or in the public Internet.