SDN promises revolutionary benefits, but watch out for the traffic visibility challenge

By Hansang Bae, director, Cascade Product Architecture, Riverbed Technology, Network World |  Virtualization, SDN, Software-Defined Networking

The only major drawback to SDN is you lose all visibility into your network traffic, making troubleshooting nearly impossible. As an example, imagine your users complaining about slow access to a database. Prior to SDN, the network team could quickly spot, for example, that a backup was slowing the network. The solution would be to simply reschedule it to after hours.

Unfortunately with SDN, you can see a tunnel source and a tunnel endpoint with UDP traffic, but crucially you cannot see who is using them. You cannot know if the culprit is the replication process, the general ledger, the email system or something else. The true top talker is shielded from view by the UDP tunnels, which means that when traffic slows and users complain, you can't readily identify where the problem lies in the network. With the loss of visibility, troubleshooting is hindered and a delay in resolution could be quite detrimental to the business.

What can you can do to stay ahead of SDN problems

Network engineers need to know about such problems, plan for them and have a tool to address them. Fortunately, some network performance management solutions let you know how packets are physically flying around the network and the logic behind the traffic. They can provide the best of both worlds as you get to see the physical network and peek inside the encapsulated SDN tunnels.

With insight into interactions among various virtual machines on each physical host, you can monitor all application traffic traversing the virtual switch, providing real-time and historical visibility into virtualized and private cloud environments. And once the packet and flow data is captured, it can be analyzed to detect end-user experience issues, TCP errors (retransmits, resets), server delay, top talking VMs, utilization and more. This is nirvana for the network manager who is now able to identify problems in the virtual network in a familiar fashion as he does in the physical network.

Love it or hate it, SDN is coming to networks everywhere, so network engineers need to determine where and how best to use the technology as well as consider how to address the network visibility challenge it imposes.

Read more about lan and wan in Network World's LAN & WAN section.


Originally published on Network World |  Click here to read the original story.
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