Cisco CEO John Chambers loves to talk about the companies that have tried to compete with Cisco and failed. He refers to companies like 3com, Nortel, Synoptics, etc \u2014 and he's right. However, here are 10 companies that have managed to thrive in this era of Cisco dominance and have stood the test of time.\nF5 Networks\nLoad balancing was once considered a market that would rapidly be commoditized, but F5 has managed to create sustainable differentiation as the "L4-7" market has evolved into "Application Delivery Controllers" (ADCs). F5 today has the broadest and deepest application relevancy and can significantly reduce the deployment time and improve the performance of applications, such as SharePoint and Exchange. F5's strategy has worked so well that it caused Cisco to dump its own product in favor of partnering with the No. 2 vendor, Citrix.\nRiverbed\nOne can argue the technical merits of Riverbed's Steelhead versus Cisco's WAAS. From people I have interviewed who have tested the two products, Riverbed can accelerate the performance of a broader range of applications than Cisco, but for many of the core enterprise applications, WAAS is close. However, the real reason many customers buy Riverbed is that it's fast to deploy and easy to manage. I also think Riverbed has done a great job of creating sustainable differentiation, after adding application optimization features over the years.\nJuniper\nOne might look at this and scratch his head, particularly enterprise network managers. While I agree that Juniper's enterprise initiatives have floundered over the years, the company is the de facto No. 2 vendor in the service provider routing space. Cisco and Juniper tend to leap-frog one another in technical superiority. But Juniper's latest releases include the T4000, MX and PTX lines, which are great products and should fuel the Cisco-versus-Juniper SP wars into the foreseeable future.\nArista\nHow's this for respect? Just a couple of years old and joining the ranks of some long-time Cisco competitors. But Arista seems to have the right mindset to create sustainable differentiation against Cisco in the data center. I had a chance to sit down with Doug Gourlay at Interop and he talked a lot about the value of staying focused. Arista will not venture into markets like ADCs or Metro Ethernet, and will remain laser-focused on data center networking. In fact, he said Arista wants to be to the data center what Juniper is to SP routing, and that's the industry\u2019s de facto No. 2.\nPolycom\nThere's arguably no company that did more good for Polycom than Cisco. Cisco's acquisition of Tandberg was supposed to kill off the niche video vendor, correct? That didn't happen, and Cisco's incidentally created a rising tide for both companies. Initially, Polycom wasn't able to do much with the opportunity created by Cisco. In 2010, though, Polycom gutted its management team and CEO Andy Miller re-tooled the company to compete. Some smart people and good execution on Polycom's part, combined with some slow product cycles on Cisco\u2019s part, allowed Polycom to grab some market share.\nAruba Networks\nOver the past five years, Aruba's share in Wi-Fi has more than doubled and is now in the high teens. While this hasn't all been at Cisco's expense (Aruba has taken share from Motorola as well), Aruba did implement a "Trojan Horse" strategy with its Airwave management tools a number of years ago. Aruba accepted that Cisco customers buy Cisco hardware, and sold Airwave into those environments to manage the solution. Then the company jumped all over the 802.11n upgrade cycle and used the Airwave footprint to grab some share.\nBrocade\nBrocade has been the market and technology leader in Fibre Channel switching for years now. It was first to have 8 Gig FC, 16 and will likely get to 32 Gig first as well. Despite much of the hype around FCoE, Brocade has kept its focus on delivering faster and more feature-rich FC and now owns about two-thirds of the market. The company appears to have a real shot now, as the shift to fabrics and software defined networks (SDNs) require data networks to be more efficient, resilient and reliable \u2014 like a storage fabric.\nHP\nUnder John McHugh, HP Networking came out of nowhere and went from relative obscurity to the No. 2 share vendor almost overnight. HP caught Cisco sleeping and managed to grab some share with value buyers at the access edge. Since then, Cisco has countered with purpose-built products that are more in line with HP pricing. HP then countered by acquiring 3Com to refresh its portfolio and challenge Cisco in the data center. Both companies are building integrated data center "stacks," so we should expect to see the once-great partners remain bitter rivals as the battle for the data center rages on.\nMicrosoft\nThere's no vendor that I can remember in recent history that has been more problematic for Cisco than Microsoft. Lync, Microsoft's UC solution, introduced new buyers into the mix that have the same level of loyalty to Redmond as network engineers have to Cisco. Cisco has spent countless hours trying to prove that its solution is not only more reliable than Lync, but cheaper and broader. This may be true, but customers buy Lync because of Microsoft familiarity, and that's a tough value proposition to compete with.\nAvaya\nBefore there was a Cisco-versus-Microsoft battle, there was Cisco versus Avaya. Most people don't realize this, but through its acquisition of Nortel, Avaya actually has over 20% share in voice (not VoIP, but all voice) meaning they control 1 out of every 5 business phones. Under Kevin Kennedy the company has streamlined much of its business, making it more agile than it was in the past, and it will continue to be a threat in the UC space.