Exchange & Outlook - Lync 2010, Load Balancing, & Bandwidth

by B. K. Winstead


How is your Microsoft Lync 2010 deployment going? Are you even looking at Lync? I recently ran a poll about Lync adoption on the Exchange & Outlook page of, and I was surprised by how many responders said they were already using or were planning a move to Lync 2010. Pleasantly surprised, I should say.

The poll results indicated that 45 percent of respondents were already running Lync 2010, and another 8 percent were using Lync 2010 through Microsoft Office 365. Further, another 24 percent said they were currently planning to upgrade to Lync 2010. That leaves less than a quarter of respondents who were sticking with their current unified communications (UC) provider, whether that was a previous version of Microsoft Office Communications Server (OCS) or a competing UC platform.

Granted, it's probably no coincidence that people in our Microsoft-centric audience show a high adoption rate for the next level of a particular Microsoft technology, and with Lync being such a strong companion to Microsoft Exchange Server, the high correlation makes that much more sense. "The world runs Exchange," said Tim Harrington, Lync architect for managed services provider, Azaleos. "The world right now is trying to decide on unified communications and what product they're going to go with. Probably less than 10 percent of companies have made a decision on what that vendor is." Obviously, shops that already have Exchange Server will find it that much easier to choose Lync for UC because of their tight integration.

Lync implementation brings some unique challenges in the area of load balancing and managing available bandwidth. As Harrington said, "Hardware load balancing is an absolute requirement for any enterprise edition installed for Lync. You have the ability to completely load balance Lync behind a hardware load balancer, including all the SIP traffic, which is not super easy and can take some troubleshooting to get done, but is definitely possible."

KEMP Technologies' chief scientist, Jonathan Braunhut, echoed this point, saying, "Lync imposes some new challenges because unlike Exchange, you've got VOIP, you've got traffic flows that are jitter- and latency-sensitive." KEMP has just announced that its line of LoadMaster load balancing appliances, both hardware and virtual, have been approved for use with Microsoft Lync 2010.

"What we've got is a well-tuned hardware load balancing offering that can handle those real-time flows with minimal degradation in call quality and user experience," Braunhut said. The LoadMaster line was previously approved for use with Exchange Server,] and it seems whenever I hear someone looking for a load balancer recommendation, KEMP is the first name mentioned. So it just makes sense that adding Lync approval is a logical step.

If you get your Lync implementation load balanced successfully, you might hope you've eliminated your worst performance problems. However, bandwidth within your network could still hold you up. "Anytime you're adding audio, video, web conferencing, desktop sharing, it's going to require quite a bit of bandwidth," Harrington said. "You should be looking at bandwidth utilization reports from the networking perspective, and not from the Lync perspective, and then adjusting any policies that you have built around Lync that can help out if needed. Maybe the network is just not provisioned right, and you need more bandwidth. But maybe you can help out by putting in QoS [Quality of Service] policies-call it mission control policies-so that you're not oversubscribing the bandwidth that's there."

Naturally, the point of all this is to know what you've got going on in your system and set it up appropriately. While Lync does bring some unique challenges, it also adds some unique and stellar productivity features to your environment. But hey, most of you already know that!

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Exchange Load Balancer 2010, Load Balancer, KEMP Technologies