I was in the local Best Buy the other day and overheard a conversation between a saleswoman and a father looking to buy a computer for his daughter. Apparently, the daughter is a designer, which of course requires lots of heavy graphics work. Anyway, the saleswoman was trying\u00a0to explain how he should invest a little bit more in an expensive graphics card because of her work. The father wouldn\u2019t hear of it. He wanted the least expensive machine possible.\nIt was a mistake.\nPart of the art of life is knowing when and where to invest your resources for maximum return. Sometimes less is, well, less and investing a bit more really can make a difference. I know you didn\u2019t come to this blog for self-help advice, but life\u2019s truism has real-world implications for wide area networks and, in particular, when selecting the Internet infrastructure underlying your SD-WAN.\n+Check out: SD-WAN: What is it and why you\u2019ll use it one day+\nSome IT managers seem to think IP connectivity is a commodity. One ISP is supposedly the same as the next and so they don\u2019t have to worry about finding the \u201cright\u201d ISP. \u00a0In fact, there can be a vast difference between Internet service providers. Getting that \u201cright\u201d Internet service can sometimes make an enormous difference in the quality of experience for your users.\nOver the years, I\u2019ve built dozens of global networks, some touching Europe, many into the Asia Pac and South America. Regardless of the region, the local ISP plays a crucial role when it comes to SD-WAN. With MPLS and leased line networks, we would focus on the time it took receive a circuit at the local premises. We\u2019d focus on the service level agreements (SLAs) and whether local loops covered by those agreements - or not. We\u2019d look for end-to-end management and want to make sure the two providers \u2014 \u00a0the ordering provider and the fulfilling one \u2014 \u00a0had the necessary network-to-network interfaces (NNIs) and management processes in place to make end-to-end delivery seamless.\nBut the performance of the overall system wasn\u2019t the issue. Say what you will about managed MPLS services \u2014 \u00a0they might be expensive, clunky and frustrating as heck to get support from the carrier \u2014 \u00a0but you knew that the line rate and quality contracted for was what you were going to receive. \u00a0\nWith SD-WAN, the ISP plays an even more crucial role precisely because there are no formal SLAs. You\u2019re trusting that the Internet provider\u2019s network is engineered for performance. When using broadband, such as cable or DSL, often the choice of ISPs is limited. But when locations connect through direct Internet access (DIA), there\u2019s often a choice of many ISPs. And while there\u2019s a lot that you can\u2019t know about their networks, you can investigate one major factor \u2014 \u00a0how the ISP connects to the rest of the Internet.\nConnections and Tier-1 backbones\nSome local ISPs connect directly to global backbones, others rely on local peering points. There\u2019s a huge difference. For one, peering points are highly oversubscribed, running at 60-70 percent capacity. With so much traffic running through them, packet drops and retransmission become far too frequent at peak periods. But even if the peering point isn\u2019t oversubscribed, local ISPs will require multiple router hops to reach the peering point. As any network engineer knows, the more hops the poorer the performance.\nIt\u2019s why when we at SD-WAN Experts evaluate local ISPs, we look very carefully at a provider\u2019s access\u00a0to the rest of the Internet. Ideally, we try to hang all locations off of one tier-1 backbone. With everyone on the same network, you will have minimized the likelihood of packets being bounced between provider networks to reach their final destination. Not guaranteed mind you, this is the Internet after all, but certainly improve the likelihood of optimum performance.\nWhat makes for a tier-1 Internet backbone? There\u2019s no award or license you can request that says \u201cTier-1 Certified.\u201d When we speak about tier-1 backbones we\u2019re talking about global backbones that peer directly with other tier-1 global backbones. The best backbones can connect directly to most parts of the world without the need to peer, or with a minimal need.\nTo find a \u201cbetter\u201d backbone look at the number of connected Autonomous Systems (AS). An AS is the reflective of\u00a0a single network, at least for Internet routing purposes. The better the network, the more direct connections you\u2019ll find the network has. See this measurement of Internet backbones from Dyn, an internet performance management company. It shows the top three backbones have ~27,000 direct connections to other networks:\nWhat may not be readily clear from the graph is the importance of knowing the specific ASN. Providers will frequently run multiple ASNs; often there are huge differences between them. China Telecom, for example, operates 4134 (China.net) and 4809 (CN2). I can tell you that CN2 is a great backbone, well connected, with a low oversubscription ratio with a packet delivery SLA of 99.5%. China.net? Less so.\nInvariably some locations will be unable to connect to a tier-1 backbone. No network has the geographic reach into every city and town across the globe. Using SD-WAN technology to combine global networks, and select the optimum network at any given time, lets you expand the footprint of any given backbone. Large organizations can afford to do this themselves, connecting regional data-centers to multiple backbone. Smaller organizations or organizations who lack a datacenter in region might consider a provider who provides that service.