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Monthly Archives: November 2011

IP Video – It’s like Living with a Teenager

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    Teenagers. Maybe you have one (or more) at home; maybe not. But we’ve all been one, so I know you can relate. Moody and unpredictable. Overly sensitive. Taking up more space than any human has a right to. High maintenance. They’re just so adorable.

    Well, it turns out we have an exploding data type on our networks that behaves much the same way – IP video. In a recent whitepaper by Cisco, it was reported that all forms of video (TV, VoD, Internet, and P2P) will be approximately 90% of the global consumer Internet traffic by 2015. And per the report, that’s 90% of what will be 966 exabytes, or nearly a zettabyte, of IP data. To see what that looks like graphically, check out this link. Although video traffic on the enterprise side will not be as heavy as that on the consumer Internet, it will increase dramatically nonetheless, and will certainly be much more than 50% of the enterprise network traffic by 2015. It looks like you’re going to need both network management and high school guidance counselor skills by 2015 to manage enterprise networks.

    With this dramatic increase in video traffic, video will be in competition with enterprise corporate data, enterprise application access, SaaS, and cloud computing. And given its tendency towards teenage behavior, you’re going to have your hands full. Below are a few details of how the characteristics of IP video can adversely affect your enterprise network.

    Unpredictable
    Video is “bursty,” or in the teenage analogy, unpredictable, which is an undesirable characteristic for networks that work best under stable conditions – predictable and consistent. Packet sizes range all over the place, and often hit the network in large bursts. And of course these bursts are tagged with high QoS (quality of service) tags, so they take precedence over your other mission critical application data. Characterization of your IP video traffic, including weeding out business traffic from surfing, is critical to the health of your enterprise network.

    Space Hog
    Video is a bandwidth hog. One HD video stream can consume up to 20Mbps of bandwidth. So if five people are trying to stream a movie, it means that they are taking up 100Mbps of your network. This may not seem like a ton of traffic, but depending on the distribution of these users on your network, and the number of users serviced, bandwidth availability can certainly become an issue. And remember, the amount of video on your network is increasing all the time.

    Overly Sensitive
    Video is also very sensitive to latency, jitter and packet loss, even more so than voice, which we covered in this blog post. These sensitive protocols demand that your network is performing at its peak level to ensure that these issues are minimized. As video becomes more common on the network, performance demands will continue to grow and become harder to reach. Specific metrics and demands of latency, jitter, and packet loss are described in more detail below with this video segment and graph:

    High-Maintenance
    Due to the high performance demands of video, it is typically tagged for the highest QoS delivery as I mentioned earlier. However, as video traffic starts exceeding data traffic, enterprises will need to maintain different quality of service between users or video types since it is self-defeating for most of the traffic on a network to have the highest QoS tagging.

    As video continues to grow, or as some might say invade, your enterprise network, it is more important than ever to plan and design your network to carry video. And just as the teenage years pass, the video phase will also pass in time, allowing networks to again hum along in a predictable pattern. That is, until the next disruptive technology come along! In next week’s blog, we’ll be providing some best practices on designing, monitoring, and managing your network to help that teenager grow up.

      Why On-the-Fly Analysis Doesn’t Work at 10G

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        Remember when Pluto was a planet and performing ad hoc network analysis was the way it was done? Whether you have already made the switch to a 10 Gigabit (10G) network or you are about to, the way in which you monitor and analyze your network must change.

        With traditional network analysis you had a lot of flexibility. Most times you simply connected your network analyzer if you had a problem, started a trace, and determined the problem. If the problem occurred in the past, you would attempt to replicate the problem and then solve the issue. But with 10G there is way too much data to attempt to reproduce problems for analysis.

        So, how do you conquer this problem using the same equipment as you did with 1 Gigabit (1G)?

        In most cases, you simply can’t. 10G and, in the future, 40G networks require different equipment to monitor 24/7. The days of using laptops and built-in network interface cards (NIC) are over. You need dedicated appliances that are purpose-built to monitor and analyze 10G networks on an ongoing basis. Reproduction is no longer a quick, smart, and feasible alternative on highly utilized 10G networks, so having a solid network forensics solution in place is essential, not only for uncovering security breaches (as most people think it is primarily used for), but also for examining common issues on your network, like spikes in utilization, drops in VoIP call quality, and increased latency – whether network or application.

        Instead of having a point-and-shoot solution as you did with 1G, you need a different approach when handling your 10G networks. With 10G, you need to identify key analysis points, put equipment in place that can monitor 24/7 with alarms and alerts, and record network data at your peak data rate. When a problem is detected, you will already have the data stored and you can simply rewind data (rather than replicate the problem), analyze that data, and identify the root cause of the issue.

        What does this cost? Is it worth it? It does require an up-front investment to monitor your 10G network, but it will save you big in the end by avoiding network downtime, improving tier one application performance, and increasing productivity within the company, with your network consistently running quickly and smoothly.

        To check out more on how to correctly analyze and monitor at 10G, check out this short video.

          How upgrading to 802.11n can impact your existing WLAN

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            In our last blog post, we reviewed the definitions and performance benefits of the new features in 802.11n. Even with the definitions and brief technical descriptions of these capabilities, there still remains a very important yet unanswered question:

            Will these upgrades affect me negatively or positively?

            Some of the upgrades can be very beneficial to your wireless service delivery, but it depends on what environment you are working in. If you are deploying in a Greenfield environment, meaning you are starting your wireless project from scratch, you can take advantage of more of these upgrades as compared to deploying in a mixed environment. In a mixed environment, you already have a wireless LAN in place and are utilizing 802.11a/b/g technology, which introduces the possibility of negative effects from some of these new features.

            With this filter in mind, let’s dissect how employing each feature differs depending on your environment and what 11n equipment is available to you.

            2-Stream, 3-Stream, or 4-Stream (MIMO):

            802.11n allows the transmission of up to 4 unique streams of data simultaneously between APs and clients – but note, although the technology allows 4-streams, there are not many commercial APs on the market that can handle this, and even fewer wireless adapters for clients. Adding these data streams increases the overall throughput, but only between compatible APs and clients, and only up to the level of the less feature-rich device.

            When working within a mixed environment it is essential to keep in mind the capabilities of all of your users. Since MIMO-enabled APs are backward compatible, it makes sense to deploy APs that will provide adequate performance both today and in the future – that’s 3-stream APs today. However, if you’re not planning on upgrading all of your clients to 3-stream, then be careful on how you “market” the new capability to the organization. Once users hear that the APs are capable of 450Mbps, they will expect that level of performance, but if they’re using a laptop that’s still 802.11g, or even 11n Draft v2.0 (2-stream at best) they will continue to see data rates far below the maximum 450Mbps data rate for 3-stream devices.

            As for Greenfield environments, assuming everyone is getting new gear, a full 3-stream roll-out seems like the way to go. Occasionally, you might get a visitor or remote employee with a 2-stream device, but the technology is backward compatible so these users will still be able to connect to your network – they’ll just experience slower data rates.

            Channel Bonding:

            The upside of channel bonding in 802.11n is that it’s been available in most 11n equipment shipped since the Draft v2.0 11n standard was in place, and requires only a simple configuration change to reap the benefits. However, if you are working in a mixed environment, channel bonding can reduce the number of available channels for legacy 802.11a/b/g equipment, and it can negatively affect your entire wireless LAN and overall data throughput. This is especially true in the 2.4GHz band (the b/g channels 1 – 11 in the US), where the channel spacing is only 5MHz and co-channel interference is already a problem. Channel bonding requires an additional 20MHz of bandwidth, essentially occupying an additional 4 channels, and using far more than 50% of the total available bandwidth in the entire 2.4Ghz range for a single AP. If channel bonding is to be used in a mixed environment, restrict its usage to the 5GHz band where the 10MHz channel spacing reduces the severity of the interference problem.

            If you are deploying in a Greenfield environment, this option is more advantageous. Just keep in mind that you might be interfering with your neighbors who are using 802.11a/b/g equipment. The perfect place to use this technology is a large campus that has few or no neighbors, as opposed to an office with many neighbors. Also, this capability will see a huge advancement with the advent of 11ac, which allows for wider channel access and less interference.

            Aggregation (A-MPDU/A-MSDU) and Short Guard Interval:

            For both mixed and Greenfield environments, these technologies are definitely worth taking advantage of, and they are often something you can’t control or configure in your AP anyway.

            Beam Forming:

            As stated in our last post, this is something that should be avoided, as it is not quite ready for primetime. Even if you are in an outdoor environment and you have multiple clients in the same general direction, it is still better to use an AP with an antenna design that favors the direction of the clients and does not attempt active tuning for each individual client like in beam forming.

            Current Commercially Available 11n Equipment:

            There are a lot of 3×3 (three transmit antennas and three receive antennas) wireless adapters and APs on the market, however these devices do not necessarily provide 3-stream throughput. If the 3×3 device you are considering advertises a maximum data rate of 300MBps, it is not 3-stream capable, and cannot be made compatible with a simple firmware update. Be sure to look for wireless adapters and APs that have 3×3:3 capabilities (with the “:3” representing the number of streams), or, because this is often not listed on the packaging, look for devices that advertise 450Mbps of throughput. And keep in mind that 3-stream APs are more common than 3-stream wireless adapters in today’s market.

            If you go to the WiFi alliance website, you can search for all the certified products that are 11n capable. You can’t do a specific search for 3-stream capabilities, so you’ll need to comb through the search results to see if the devices are 11n and 3-stream capable. To have the best chance of finding 3-stream devices on the website, look for devices that were certified in 2011, and look at the certificate for each device which clearly lists the number of streams tested.

            If you want to learn more about what upgrades you should be looking at when deploying 11n, check out this short video clip that goes into details for each capability and outlines what is best for your company.