With all the attention garnered by the higher OSI layers, we sometimes forget that all seven layers are necessary for communications to work. So when troubleshooting, for example, don't forget about the basic stuff.Take power, for example.\u00a0 We were recently reminded how important Layer 1 is to PCs and communications equipment when, after a week of troubleshooting, Joanie (with help) traced an intermittent problem to a lowly cabling issue.We hear lots of talk about switches, firewalls, network monitors, traffic-shapers and other devices working at "Layers 4 - 7" these days. This gives the impression that anything below Layer 4 is old hat.\u00a0But nothing could be further from the truth.Let's start by thinking about an "IP service."\u00a0 Indeed, IP (Layer 3) is perhaps the most visible layer from a management perspective.\u00a0 Nevertheless, IP packets require a link layer (Layer 2) below them, often performed by either frame relay or PPP.\u00a0 And the link layer requires a physical layer (Layer 1) below it, including connectors and cabling.Years ago, the physical layer was at the forefront of the networking industry. The entire time-division T-1 multiplexing industry was based on intelligent control of Layer 1 parameters.\u00a0 Various framing formats, including D4 framing and Extended Superframe Format, sit firmly at Layer 1.\u00a0 Issues that seem positively ancient, such as bit density for T-1 lines, are Layer 1 issues.\u00a0 But these constraints still must be met regardless of the upper-layer protocols in use.As mentioned, Layer 1 also addresses connectors.\u00a0 Both the physical and the electrical characteristics must be appropriately matched for communications to occur.\u00a0 Just as you can't plug a U.S.-format 110-volt appliance into a European 220-volt circuit without both a voltage adaptor and a physical plug adaptor, you have to make sure your communications connectors are appropriately matched.\u00a0In fact, we still have a major issue on notebook computers in that an RJ-11 phone connector can physically go into the RJ-45 Ethernet adaptor.\u00a0 Not only does this Layer 1 incompatibility not work; the ringing voltage on a phone line can wreck an Ethernet connector.Bottom line?\u00a0 It's great to invest in innovation at the higher-layer protocols.\u00a0 But if you ignore the lower layers, you're likely to be building the proverbial house on shifting sand.