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The subnet mask defines how large the local network is. For devices within a single network, no router is needed. This is accomplished with a device that has a connection to both networks, that is used as a middle man to hand that packet across. In order for a data packet to get to another “Network”, it has to be routed. Well- It means that the full values of the first 3 octets, and none of the last octet, are used to define “Networks”, while the last octet is used to define the members of those networks.ĮG, if we had a subnet mask of 255.255.0.0, then the first two octets are used for networks, and the last two octets are used for members of those networks. Most home networks will use a subnet mask of 255.255.255.0. So, what is a subnet mask, and what does it do? Basically, it divides the IP address space up. Each computer needs to have a unique number in order for other computers to send it data. There are 4 numbers, and 4X8=32 Eg, a 32bit number. The values given between the decimal points is exactly equal to a value that can be stored in 8 bits, which is why each of these values is called an ‘Octet’. The decimals are there for human convenience, as the number is really just a 32bit integer, expressed in binary- as far as the computer is concerned. An IP network has 4 decimal separated numbers, between 0 and 255. I will now explain what a subnet mask is, and how it works- Later, I will explain what the default gateway is, and what it does.įirst up- IP network addressing. Specifically, it wants to know what your “Default Gateway”, and your “Subnet Mask” are. In addition to your IP address, your network configuration dialog will want to know some other information. To understand what that means, you need to understand what a subnet mask is, and what it does, but for now, know that yours does not all live in the same subnet, which is why it is “Multihomed.” With that in mind, here is a rambling and horrible attempt at explaining subnets in a hurry. Most private networks will all live inside the same subnet. The kind of network you are mentioning is called a “Multihomed Network”. Bear in mind, I am a better network admin than I am a teacher. I will link them at the bottom, then I will try to explain as best I am able. Let me get some outside sources to help explain what I am getting at here. Investigate if there is a lack of valid route between the subnets- then ask the site’s NOC if this is purposeful, and to advise. IIRC, the EX2 and pals do have more than one ethernet interface. Sadly, the single bay units do not have more than one physical interface, making that impossible. If your mycloud had more than one gigabit ethernet port, then I would suggest setting it with two IP addresses- one in each subnet, and attaching it accordingly. This keeps annoying snot nosed kids in the lobby from sending pornographic print jobs to the printer in HR, among other things. Often, to prevent public users from gaining access to privileged hardware on a wired network, a location will PURPOSEFULLY segregate the subnets, and PURPOSEFULLY not define routes between them. If it has an interface in that subnet, it will forward the packet. The router accepts the packet, reads the header and sees that it is destined for that other subnet. If so, there will be an entry that says “Send it to this IP address”. When a packet is destined for the “Foreign” subnet, the computer checks its routing table, and sees if there is a route defined for that subnet. One lives in one subnet, and one lives in the other. Both subnets’ routing tables need to have valid routes to get from their subnet to the other, and situations where data can only travel one direction are entirely possible. There is a reason you need to check in both directions. What you need is a route between the subnets. You can do the pinging from any machine in the two subnets that you have access to. If your device is not reachable, it will instead say “CONNECTION TIMED OUT” and have 100% packet loss.ĭo this in both directions. Minimum = 1ms, Maximum = 3ms, Average = 2ms Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),Īpproximate round trip times in milli-seconds (this is me pinging my own mycloud, just to demonstrate what it looks like.) ping 192.168.0.129 You will know almost right away if you are getting responses, as the device should respond to the ping requests with a response time in ms. Say you know the IP addresses of a device in each of the subnets.įrom the X.X.1.X subet, you ping that known IP in the X.X.2.X subnet, and see if you get a response.
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