So another environment where you may need to deploy is outdoors. One of the challenges with deploying outdoors is animals. You may have to deal with wildlife and insects. Insects and animals can be kind of a pain to deal with. They mess with cable. They do a bunch of things with cable. So you need to protect your devices and your cable against wildlife. So if can you look at the different sources of attacks on your devices outdoors, there's things like rats, and rodents, and moths, different kinds of insects like ants and cicadas and crows. These different insects and animals do different things to cable. So when you do a deployment, you can deal with these different animals. The thing is, when you inspect your deployments, when you can figure out which animals are attacking you. Like rodents, for example. Rodents are animals that have teeth that grow inside their mouths and they keep growing forever. It's not like people, we have a set of teeth that come in and they just stay there and that's it. But rodents have teeth that keep growing and growing. So they like to chew on things. They like to chew on things to know their teeth down where it get too long, and they really like to chew a cable. Because that's a nice metal where they can really grind down their teeth. That's the prompt for your cable. So what you can see is, here's a cable that was chewed on by a rodent. The sheath is ripped apart, some of the wiring is exposed and so on. On the other hand, you have things like moths and ants. These things burrow into cables and they lay eggs and they build nest. The problem is insects are conductive, when they get inside cable they can cause interference. They can cause short circuits where information can go between cables. A lot of times they move around so they can create transient interference. This can be really hard to debug. There's also things like crows and birds. Crows and birds like to build nest. They're looking around for sticks and twigs because they went to build nests for their eggs, and when they see cable, it looks really good to them. Because it's a nice big thick piece or something that they can pull up for their nest. So what crows tend to do is they tend to pull that cable and rip at it. Here's a cable that was attacked by some sort of bird. You can see it's got some of his sheath pulled up. So in general, what you can do is, whether you deal with cables or you deal with outdoor devices, hen you see damage to them, you can look at it and inspect it and you can consult this chart, and you can get some sense of what sort of wildlife attacked your device. Then you can build your device to be more robust against it. By understanding which particular kind of animal is attacking you, then you can know how to build your device to make it more resilient. So how can we actually protect against these problems? Well, to gain an insight into that, let's first study the sources. What's sort of different sources caused these problems. So over here on the far right, I have a pie chart which breaks down the different types of failure modes for different kinds of outdoor equipment. So if you have a deployment like a bunch of outdoor wires are IoT devices. What causes these interference practice. Well, people have done a lot of studies. I am showing results for a particular study here. What we found is that cables failing cause a lot of problems. You used to have a cable deployed, regular cable failures that cause about 21 percent of outages. Connection failures cause about 21 percent of outages. Devices failing cause about 20 percent of outages. But wildlife causes about 20 percent of outages as well. So wildlife is actually a big source of outdoor failures. As you make your devices more and more robust to other sorts of failures, that percentage is only going to increase. So if we zoom into that wildlife part there, if we want to understand what types of animals cause damage, that's the other pie chart here. So what I'm showing here is the type of animal that causes the damage. We can see that rodents are a big cause of outages. Insects are also the cause of outages, and birds are a large but smaller source of outages. So you can see that the type of animal that attacks outdoor systems is actually pretty diverse. There's lot of different kinds of animals that are sources of outages in outdoor deployments. So this is a lesson for us because when we do IoT deployments, we need to make our devices robust against multiple different kinds of the animals. So when we do this, we need to pay attention to the different types of actions that these animals take on our cables, in our devices. Are they chewing on cables? Are they building nests with it? Are they burrowing into it and so on. So given that, how can we protect our systems against wildlife? Well, there's a number of countermeasures that we can use against wildlife to protect our devices. So one thing we could do is just make our devices strong. If we have cable, we can make it high strength, put a lot of armor outside of it. We've put PVC wrapping around it, metal and so on. When people study wires, they actually measure how resistant they are to biting. There's a tool to do this too, it's called a [inaudible] , which measures how much you can squish a cable, how much biting force there is. You can look up how much biting force a crow has or an ant has or a rodent has and so on. Then you can figure out what's attacking your system then by cable that's resilient to that much force. Another thing you can do is by cable wrap. So if you have a set of cables deployed, you can wrap them. There's certain tapes you can deploy on the outside. There're certain PVC sheets you can use or stainless steel meshes and so on. You can put squirrel proof covers on your devices and so on. Another thing you could do is fill in gaps and holes. This is a good technique to deal with insects. Because insects often don't chew into cable, they look for holes that already exists and they get in there and they make nest. So what you can do is you can inspect your deployments and put in silicone adhesive in parts where the outer part of the cable is exposed. Another thing you can do is use cord that taste bad to animals. They sell wiring with sheaths where the PVC is infused with irritants. One thing they do is they sell cable with pepper spray in it. They have capsaicin in there. So when animal bite into it, it feels really hot and spicy to them. There's other sorts of cable that have very bitter compounds in them. Like denatonium benzoate, which is the most known bitter compounds. So when an animal bites into it, taste really bitter they don't like that. In the type of bad tasting cord you use, depends on the type of animal that's attacking you. If it's a crow, crows can't tease capsaicin, birds can't taste pepper spray. So you wouldn't use that. You'd use a denatonium benzoate for that. So what you can do is you can buy cables with these different irritants in them to protect against the animals. So what I've done here is I've talked about wildlife as a threat to your outdoor deployments, and giving you some countermeasures that you can use to protect your outdoor deployments from these animals.
