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Author Archives: jaybotelho

Why Packets Count

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    A packet is the elemental source of data on a network. Packets are self-contained, including not only the information that is to be communicated, but also the routing instructions, addresses, protocols, etc. that allow the information to be correctly delivered, and possibly acknowledged. Packet delivery on a network is a lot like a letter in snail mail, with the contents of the envelope being the information to be transmitted, the envelope containing address and routing information, and the stamp describing the protocol to be used in delivery – first class, signature required at delivery, acknowledgement of receipt, etc. Also, just as with snail mail, issues can occur in transit that either damage the letter, or as many of us have experienced, prevent the letter from being delivered at all.

    Extending this analogy, the contents of a letter, or in the case of packets the payload, are really of no concern to the Postal Service, and typically remain hidden inside the envelope. All the Postal Service needs to know is the address and the mode of delivery. They then determine the routing, without concern for the contents, until delivered to the final recipient. Only then do the contents (payload) become important.

    So, what happens when something goes wrong? How would you even know it went wrong? Well, in the case of network analysis, this is where protocol and packet analysis become important. Often used interchangeably in the industry, protocol and packet analysis are in fact quite different. Protocol analysis relates strictly to the routing and delivery of packets. In terms of our Postal Service analogy, protocol analysis is performed using only the envelope – the contents of the envelope are never analyzed. Packet analysis goes one step further, performing both protocol and packet payload analysis.

    Network engineers are typically concerned with only the delivery of data on the network, and not the data itself, so why worry about packet analysis at all? Isn’t protocol analysis sufficient? Well, in many cases yes, so it’s the best place to start. But even our simple Postal Service analogy can once again help us in understanding why packet (payload) analysis is important. Let’s say you’re communicating with a family member using letters (yes, the world used to communicate in this highly archaic manner just a few short decades ago), and suddenly your weekly communication is disrupted. Why didn’t you get the response you were expecting? Well, with protocol analysis we can see that (a) no communications have been processed that were addressed to you and (b) your “pen pal” recently received additional communications addressed to them. Even though you can see from the return address on the envelopes that one of the correspondences was from the Publishers Clearing House, you assume that’s just the typical junk mail and has no bearing on the delayed response. But let’s say you can see the contents of all of the letters as well (packet analysis), and that the letter from the Publishers Clearing House was not your typical junk mail – it was a notification that your “pen pal” just won $10 million dollars. With that bit of information the source of their distraction becomes clear, and it’s easy for you to understand why you didn’t hear back in the typical response time.

    The above example made one basic, yet often unstated, assumption about our ability to even analyze the Postal Service (network). It assumed we had the proper tools in place, and were using them 24×7, to perform ongoing, real-time analysis, all the while archiving our network data so we could go back and analyze it as necessary. As in our example, it isn’t always immediately obvious that something did or did not happen as expected. You need constant monitoring, with ongoing data storage, so you can analyze the problem as it happens, not wait for it to happen again and hope you catch it. Way more network analysis time is spent trying to reproduce problems rather than solve them. Ongoing network monitoring based on packet analysis gives you all the information you need to analyze your network at its most elemental level.

    So, the next time you sit down for some quality network analysis time, take a quick look at the packets per second. And then imagine that many little letters being delivered each second via your network infrastructure. At least for me, it provides a whole new perspective on just how hard my network works, and just how important my network monitoring and analysis software is to me when something goes wrong.

      The State of the Network: Wired vs. Wireless

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        In a November article by John Cox of NetworkWorld, he pointed out two very important facts about networks as we know them, or at least how we use them:

        • In June WLAN vendor Meraki found that smartphones and tablets have overtaken computers on Wi-Fi networks.
        • Colleges and universities have spent the last decade and lots of money running Ethernet cables to dorm rooms and now are discovering that 50% to over 90% of those wired ports are never used.

        Our devices are now designed for wireless network access, and the younger generation rarely even considers connecting a computer to a wired port. Even for me, a guy who started his career before PCs (yes, old as dirt), I often find myself in a hotel room with a wired Ethernet port that I can’t connect to because I’ve stopped carrying a cable, so I need to rely on the wireless network (which usually performs much more poorly).

        But that won’t be for long. With 802.11n, the latest evolution in WLANs, maximum throughput is increasing tenfold, enabling the dream of reliably streaming video and walking into our company headquarters and having our mobile phone automatically transition from the cellular network to the WLAN to take advantage of better signal strength.

        So where does that leave LAN infrastructure and should you plan on investing in more LAN infrastructure when users’ expect wireless?

        Do you imagine devices retrograding back to wired or do you see them progressing to wireless?

        Actually, I don’t expect to see any significant changes. In the home, where wired ports never really seemed to catch on, even in new development, wireless will be king, and will most certainly grow in scope. Not only will your computer access be wireless, your TV, DVR/set top box and audio equipment will also be wireless, enabling new heights in shared media access. As for the corporate environment, it’s hard to imagine commercial construction without wired access. It may diminish somewhat, especially in large cube farms or “bullpit” areas, but closed offices will continue to be wired. Certain computing applications, especially those employing high performance computing, will still benefit from the wired connection, and commercial landlords don’t want to limit the applicability of their properties. Universities may be the exception to this status quo approach. With their young and mobile “customers,” wireless is the only approach that makes sense and the up to 90% unused wired ports in university dorm rooms have not gone unnoticed as an unfortunate waste of money.

        Even though wireless seems to be stepping in the door while wired is stepping out, there is a state of limbo between the two and there will be for more years to come. And even though wireless is gaining ground, the backbone of every wireless network is wired, and this is not likely to change for a very long time, if ever. So where does that leave you, and how do you ensure that you are reaping the full potential of your wireless as well as your wired infrastructure?

        The key is that your network is now a convergence between wired and wireless, and it must be managed accordingly. You need network management solutions that can handle both networks, simultaneously, because this is how your network traffic is delivered. Here are three key reasons for considering converged network management and troubleshooting:

        • Elimination of multi-vendor, multi-product solutions, allowing for better management and cost savings.
        • Better visibility into which network is causing network problems: wired or wireless. Issues can easily be on either side.
        • Increased scalability. With both wired and wireless network getting faster all the time, it’s important to have a solution in place that’s been designed from the start with high speed networks (i.e. wired) in mind.

        Wireless is starting to reach the throughput and applicability of wired networks with 802.11n, but increased capability leads to increasing user demands, requiring careful planning when implementing wireless network upgrades, including the ability to monitor your wireless and your wired network simultaneously. Converged network management is your only option for handling the higher throughput of improved wireless networks, allowing you to quickly monitor and analyze traffic regardless of the network it traverses.