Terry Slattery
Terry Slattery, is a senior network engineer with decades of experience in the internetworking industry. Prior to joining Chesapeake NetCraftsmen as...
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Terry Slattery | July 29, 2012 |


Want a Five-Nines Network?

Want a Five-Nines Network? How can you get close to this? Most networks blow that figure in the first month. Here are some tips to build the foundation.

How can you get close to this? Most networks blow that figure in the first month. Here are some tips to build the foundation.

Converged networks today rarely have the availability metric that was common for the historical voice network: five-nines, or 99.999% availability. That's 5.25 minutes of downtime per year. How can you get close to this? Most networks blow that figure in the first month.

In the next series of blog posts, I'm going to describe the steps that you can take that will make your network much more stable and get you much closer to that magic five-nines metric.

The One True Version
Run one OS version. Don't get into the trap of not upgrading some devices simply because they are not currently having a problem. When you start mixing OS versions, you start encountering problems where network protocol operation is slightly different between the versions, due to different bug fix levels and enhancements to the protocol. You will eventually have a situation arise where you can't implement some new functionality because of older OS versions in some part of the network. Or you'll be unable to migrate to a new OS with new features in your core because it no longer interoperates correctly with the older OS versions.

A good example of OS version interactions is with the Spanning Tree Protocol (STP). Older switches implement the standard spanning tree protocol, 802.1D. Newer switches can run Rapid Spanning Tree, 802.1W, which offers significantly improved convergence times as well as features that help prevent spanning tree loops. The new switches will fall back to 802.1D in order to interoperate with the older switches. The result is that your network can’t take advantage of the new functionality. It is more susceptible to spanning tree loops. (Have you ever debugged an STP loop before? Read up on it if you haven't so you know what's involved.)

The other advantage of running one OS version is that you only have one set of bugs to track. You know what configuration options work for that OS version and which configurations to not use.

When I recommend one OS version, that's one per hardware platform. With a few exceptions, most vendors have a slightly different OS version for each hardware platform. Identify the OS that you will run for each hardware platform and make sure that it is installed on all the devices of that model. You may have an exception from time to time, but make sure that they are exceptions and that the reasons for the exception are clearly documented. When the exception ceases to exist, bring the device into compliance with the rest of the network. If you have a situation where an edge device needs the functionality of an obsolete piece of network hardware, isolate that network hardware too. Make it part of the edge device configuration so that you can move forward with the rest of your network.

Current Hardware, Clean Rooms, Neat Racks
You can't run a current OS version on old equipment. You don’t have to be on the bleeding edge of hardware deployments, but you should have a regular hardware refresh program. One site that I've worked with had a policy of upgrading one third of their hardware each year. That's the most aggressive program I've seen. I recommend the same process, perhaps with a longer timeframe of 4 years--updating one-fourth of the hardware each year.

Some organizations can't afford to perform hardware refreshes that often. Then consider dividing the network into zones and upgrading a zone at a time. A zone could be based on function, such as core and distribution, or it could be based on geography, such as Eastern US or Europe. The hardware within a zone is of the same vintage, allowing you to use standard configurations and operational policies and procedures across the zone. This reduces your management load and makes it easier to troubleshoot.

In some cases, you can push the old hardware out to the edge to replace even older gear there. This is just another way of segmenting the network and upgrading parts of it. With the re-allocation approach, you are keeping the old hardware, but moving it into areas of the network where the hardware and software deficiencies have less impact on the network and on the business.

While you're doing your upgrades, make sure that the equipment rooms are kept clean. There's nothing like dust and dirt getting into the gear to cause fan failures, which cascade into overheated equipment, which then doesn't last as long. Dust in equipment can also cause intermittent failures, which are extremely difficult to troubleshoot, consuming massive amounts of staff time to diagnose.

Make sure that your computer room staff has easy access to cabling of the proper types and lengths. A lot of time is typically wasted in the search for the right cable. And have a process for handling suspected bad cables. It is silly for a bad cable to repeatedly get installed simply because it was available nearby.

Finally, keep the racks neat so that it is easy to track connections between equipment. Remove old cables so that you aren't looking at the back of a piece of equipment and wondering if that disconnected cable was supposed to be connected to something. A clean, well-designed cabling system and rack layout will yield benefits in reduced troubleshooting time as well as reducing the time that is required to replace equipment as your hardware is refreshed.

Standardizing on OS versions and hardware versions is a fundamental practice of organizations that operate highly reliable networks. An underlying theme in their operations is the application of good, basic procedures that are standardized across multiple facets of their operation. With Standard Operating Procedures (SOPs), they have repeatable processes that allow them to achieve greater operational efficiency with fewer errors than organizations that don't adopt standard processes.


Enterprise Connect Orlando 2018
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March 7, 2018

Video collaboration is experiencing significant change and innovation-how can your enterprise take advantage? In this webinar, leading industry analyst Ira Weinstein will present detailed analysis

February 21, 2018

Business agility has become the strongest driver for enterprises to begin migrating their communications to the cloud-and its a benefit that enterprises are already realizing. To gain this benefit

February 7, 2018

Enterprises are starting to grasp the critical importance of security and compliance in their team collaboration deployments. And once the risks are mitigated, your enterprise can integrate these n

March 12, 2018
An effective E-911 implementation doesn't just happen; it takes a solid strategy. Tune in for tips from IT expert Irwin Lazar, of Nemertes Research.
March 9, 2018
IT consultant Steve Leaden lays out the whys and how-tos of getting the green light for your convergence strategy.
March 7, 2018
In advance of his speech tech tutorial at EC18, communications analyst Jon Arnold explores what voice means in a post-PBX world.
February 28, 2018
Voice engagement isn't about a simple phone call any longer, but rather a conversational experience that crosses from one channel to the next, as Daniel Hong, a VP and research director with Forrester....
February 16, 2018
What trends and technologies should you be up on for your contact center? Sheila McGee-Smith, Contact Center & Customer Experience track chair for Enterprise Connect 2018, gives us the lowdown.
February 9, 2018
Melanie Turek, VP of connected work research at Frost & Sullivan, walks us through key components -- and sticking points -- of customer-oriented digital transformation projects.
February 2, 2018
UC consultant Marty Parker has crunched lots of numbers evaluating UC options; tune in for what he's learned and tips for your own analysis.
January 26, 2018
Don't miss out on the fun! Organizer Alan Quayle shares details of his pre-Enterprise Connect hackathon, TADHack-mini '18, showcasing programmable communications.
December 20, 2017
Kevin Kieller, partner with enableUC, provides advice on how to move forward with your Skype for Business and Teams deployments.
December 20, 2017
Zeus Kerravala, principal analyst with ZK Research, shares his perspective on artificial intelligence and the future of team collaboration.
December 20, 2017
Delanda Coleman, Microsoft senior marketing manager, explains the Teams vision and shares use case examples.
November 30, 2017
With a ruling on the FCC's proposed order to dismantle the Open Internet Order expected this month, communications technology attorney Martha Buyer walks us through what's at stake.
October 23, 2017
Wondering which Office 365 collaboration tool to use when? Get quick pointers from CBT Nuggets instructor Simona Millham.
September 22, 2017
In this podcast, we explore the future of work with Robert Brown, AVP of the Cognizant Center for the Future of Work, who helps us answer the question, "What do we do when machines do everything?"
September 8, 2017
Greg Collins, a technology analyst and strategist with Exact Ventures, delivers a status report on 5G implementation plans and tells enterprises why they shouldn't wait to move ahead on potential use ....
August 25, 2017
Find out what business considerations are driving the SIP trunking market today, and learn a bit about how satisfied enterprises are with their providers. We talk with John Malone, president of The Ea....
August 16, 2017
World Vision U.S. is finding lots of goodness in RingCentral's cloud communications service, but as Randy Boyd, infrastructure architect at the global humanitarian nonprofit, tells us, he and his team....
August 11, 2017
Alicia Gee, director of unified communications at Sutter Physician Services, oversees the technical team supporting a 1,000-agent contact center running on Genesys PureConnect. She catches us up on th....
August 4, 2017
Andrew Prokop, communications evangelist with Arrow Systems Integration, has lately been working on integrating enterprise communications into Internet of Things ecosystems. He shares examples and off....
July 27, 2017
Industry watcher Elka Popova, a Frost & Sullivan program director, shares her perspective on this acquisition, discussing Mitel's market positioning, why the move makes sense, and more.
July 14, 2017
Lantre Barr, founder and CEO of Blacc Spot Media, urges any enterprise that's been on the fence about integrating real-time communications into business workflows to jump off and get started. Tune and....
June 28, 2017
Communications expert Tsahi Levent-Levi, author of the popular blog, keeps a running tally and comprehensive overview of communications platform-as-a-service offerings in his "Choosing a W....
June 9, 2017
If you think telecom expense management applies to nothing more than business phone lines, think again. Hyoun Park, founder and principal investigator with technology advisory Amalgam Insights, tells ....
June 2, 2017
Enterprises strategizing on mobility today, including for internal collaboration, don't have the luxury of learning as they go. Tony Rizzo, enterprise mobility specialist with Blue Hill Research, expl....
May 24, 2017
Mark Winther, head of IDC's global telecom consulting practice, gives us his take on how CPaaS providers evolve beyond the basic building blocks and address maturing enterprise needs.
May 18, 2017
Diane Myers, senior research director at IHS Markit, walks us through her 2017 UC-as-a-service report... and shares what might be to come in 2018.
April 28, 2017
Change isn't easy, but it is necessary. Tune in for advice and perspective from Zeus Kerravala, co-author of a "Digital Transformation for Dummies" special edition.
April 20, 2017
Robin Gareiss, president of Nemertes Research, shares insight gleaned from the firm's 12th annual UCC Total Cost of Operations study.
March 23, 2017
Tim Banting, of Current Analysis, gives us a peek into what the next three years will bring in advance of his Enterprise Connect session exploring the question: Will there be a new model for enterpris....
March 15, 2017
Andrew Prokop, communications evangelist with Arrow Systems Integration, discusses the evolving role of the all-important session border controller.
March 9, 2017
Organizer Alan Quayle gives us the lowdown on programmable communications and all you need to know about participating in this pre-Enterprise Connect hackathon.
March 3, 2017
From protecting against new vulnerabilities to keeping security assessments up to date, security consultant Mark Collier shares tips on how best to protect your UC systems.
February 24, 2017
UC analyst Blair Pleasant sorts through the myriad cloud architectural models underlying UCaaS and CCaaS offerings, and explains why knowing the differences matter.
February 17, 2017
From the most basics of basics to the hidden gotchas, UC consultant Melissa Swartz helps demystify the complex world of SIP trunking.
February 7, 2017
UC&C consultant Kevin Kieller, a partner at enableUC, shares pointers for making the right architectural choices for your Skype for Business deployment.
February 1, 2017
Elka Popova, a Frost & Sullivan program director, shares a status report on the UCaaS market today and offers her perspective on what large enterprises need before committing to UC in the cloud.
January 26, 2017
Andrew Davis, co-founder of Wainhouse Research and chair of the Video track at Enterprise Connect 2017, sorts through the myriad cloud video service options and shares how to tell if your choice is en....
January 23, 2017
Sheila McGee-Smith, Contact Center/Customer Experience track chair for Enterprise Connect 2017, tells us what we need to know about the role cloud software is playing in contact centers today.