Subnetting
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@travisdh1 said in Subnetting:
@pete-s said in Subnetting:
@travisdh1 said in Subnetting:
@romo said in Subnetting:
@wrcombs Classful networking was replaced with CIDR- Classless Inter-Domain Routing, which basically allows you to subnet your network to whatever size you want without really taking into consideration the specific IP ranges that where used before for subnett classes before.
So as you mention, it is totally find today to use the 10.X.X.X and subnet it to only have 254 hosts in the network when using a 255.255.255.0 mask if that is what you require for network.
I tend to use a lot of different 10.x.x.x/24 subnets when working with clients, just because of the headaches caused by using a 192.168.0.x/24 or 192.168.1.x/24 that all the consumer junk defaults to.
That's only a problem if you connect consumer junk to the LAN without first setting the IP or setting it to DHCP if applicable.
But maybe it's the clients that hooking up gear on their own. In that case they deserve to be punished!
I've got way to many people that need punished. They like to buy random stuff and then call us and whine when it doesn't work.
I hear you!
Well, I like 192.168.x.x since there are 65536 IPs available - and more than enough even if you exclude 192.168.0.x and 192.168.1.x and the network and broadcast addresses.
I leave 10.x.x.x to enterprise networks.
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@pete-s said in Subnetting:
Well, I like 192.168.x.x since there are 65536 IPs available - and more than enough even if you exclude 192.168.0.x and 192.168.1.x and the network and broadcast addresses.
I use the 10 network because I usually make use of the client's address or location id or such in the 2nd and 3rd octets.
One site with an address of 825 Main Street is on the 10.8.25.0/24 subnet.
Another customer with multiple locations is
Main Office: 10.202.0.0/23 (was 10.202.1.0/24, but needed to grow)
Office 2: 10.202.20.0/24
Office 3: 10.202.30.0/24
Office 4: 10.202.40.0/24 -
@jaredbusch said in Subnetting:
@pete-s said in Subnetting:
Well, I like 192.168.x.x since there are 65536 IPs available - and more than enough even if you exclude 192.168.0.x and 192.168.1.x and the network and broadcast addresses.
I use the 10 network because I usually make use of the client's address or location id or such in the 2nd and 3rd octets.
One site with an address of 825 Main Street is on the 10.8.25.0/24 subnet.
That's a novel idea. Haven't seen that before.
Another customer with multiple locations is
Main Office: 10.202.0.0/23 (was 10.202.1.0/24, but needed to grow)
Office 2: 10.202.20.0/24
Office 3: 10.202.30.0/24
Office 4: 10.202.40.0/24So 202 symbolizes the location of the main office?
Well, it's a private address space so different customers can use the same IP ranges. So I'd just do something like this:
Main Office: 192.168.10.0/23
Office 2: 192.168.20.0/24
Office 3: 192.168.30.0/24
Office 4: 192.168.40.0/24 -
@romo said in Subnetting:
@wrcombs Classful networking was replaced with CIDR- Classless Inter-Domain Routing, which basically allows you to subnet your network to whatever size you want without really taking into consideration the specific IP ranges that where used before for subnett classes before.
So as you mention, it is totally find today to use the 10.X.X.X and subnet it to only have 254 hosts in the network when using a 255.255.255.0 mask if that is what you require for network.
SO funny story, I ended up watch the video and doing the reading on this last night (its in the progression)
Subnetting in General is kind of confusing the more videos I watch and the deeper I get into it.
How do those in the community do the subnetting they need?
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@wrcombs said in Subnetting:
Subnetting in General is kind of confusing the more videos I watch and the deeper I get into it.
It's SO simple. Something is definitely wrong. It's just a mask and totally logical.
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@wrcombs said in Subnetting:
How do those in the community do the subnetting they need?
Step One: Avoid common consumer ranges (e.g. 192.168.0.x and 192.168.1.x)
Step Two: Determine reasonable number of IPs needed (say 50 or 300)
Step THree: Make sure we choose a subnet many times larger than that (say 1000 or 2000)
Step Four: If the subnet results in needed over 4000 IPs, consider VLANingTHat's it. SO easy. THere's nothing to it. Just default to 2000 and pick a different range each time in case customers want to connect to each other. There's nothing confusing, hard, or magic.
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THe smallest that I will ever deploy is a /23 and really, a /22 is the smallest I should consider. There's no reason to be smaller than that unless you have a very special case.
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@scottalanmiller said in Subnetting:
THe smallest that I will ever deploy is a /23 and really, a /22 is the smallest I should consider. There's no reason to be smaller than that unless you have a very special case.
Yeah, we still have /24 all over the place. Ends up being a pain because you run out of address space for even small places.
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@scottalanmiller said in Subnetting:
@wrcombs said in Subnetting:
Subnetting in General is kind of confusing the more videos I watch and the deeper I get into it.
It's SO simple. Something is definitely wrong. It's just a mask and totally logical.
I feel like it should be extremely simple and logical, but when I'm watching the videos and the instructor is saying ;
Here find the Network address and broadcast address of this IP in CIDR notation;
192.168.129.0/24
I know that off top of my head is;
the mask is 255.255.255.0
Network 192.168.129.0
first usable is 192.168.129.1
Broadcast is 192.168.129.255
last usable is 192.168.129.254but when the questions are "you need 4 networks which subnet mask would you use on this ip: 10.1.1.25"
I freeze up. I know that /26 gives me 4 networks with 64 hosts per network, so my IP scheme should be
10.1.1.25 /26
255.255.255.192At least I think that's right. I was told I would need a chart and I would need to study the chart to make it quick - I'm just having a hell of a time understanding it..
I probably just need to practice
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@wrcombs said in Subnetting:
@scottalanmiller said in Subnetting:
@wrcombs said in Subnetting:
Subnetting in General is kind of confusing the more videos I watch and the deeper I get into it.
It's SO simple. Something is definitely wrong. It's just a mask and totally logical.
I feel like it should be extremely simple and logical, but when I'm watching the videos and the instructor is saying ;
Here find the Network address and broadcast address of this IP in CIDR notation;
192.168.129.0/24
I know that off top of my head is;
the mask is 255.255.255.0
Network 192.168.129.0
first usable is 192.168.129.1
Broadcast is 192.168.129.255
last usable is 192.168.129.254but when the questions are "you need 4 networks which subnet mask would you use on this ip: 10.1.1.25"
I freeze up. I know that /26 gives me 4 networks with 64 hosts per network, so my IP scheme should be
10.1.1.25 /26
255.255.255.192At least I think that's right. I was told I would need a chart and I would need to study the chart to make it quick - I'm just having a hell of a time understanding it..
I probably just need to practice
The "cheat sheet" I use: https://www.calculator.net/ip-subnet-calculator.html
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@travisdh1 said in Subnetting:
@scottalanmiller said in Subnetting:
THe smallest that I will ever deploy is a /23 and really, a /22 is the smallest I should consider. There's no reason to be smaller than that unless you have a very special case.
Yeah, we still have /24 all over the place. Ends up being a pain because you run out of address space for even small places.
we typically only use /24 because 253 (without network address/ broadcast address) host addresses are plenty for a 3 terminal 1 Server site.
I don't think there was ever time we needed 500+ address like Scott is using, but That's not to say it wont happen. in the future when I move on.
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@travisdh1 said in Subnetting:
@scottalanmiller said in Subnetting:
THe smallest that I will ever deploy is a /23 and really, a /22 is the smallest I should consider. There's no reason to be smaller than that unless you have a very special case.
Yeah, we still have /24 all over the place. Ends up being a pain because you run out of address space for even small places.
Yeah, these days every little thing uses an IP address, and tons of people have phones, watches, etc. that all use them as guests. Even a tiny place can go through thousands.
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@wrcombs said in Subnetting:
but when the questions are "you need 4 networks which subnet mask would you use on this ip: 10.1.1.25"
That's gibberish. There's no way to know based on what is stated.
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@wrcombs said in Subnetting:
we typically only use /24 because 253 (without network address/ broadcast address) host addresses are plenty for a 3 terminal 1 Server site.
Only if you don't have any guests on it.
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@wrcombs said in Subnetting:
we typically only use /24 because 253 (without network address/ broadcast address) host addresses are plenty for a 3 terminal 1 Server site.
Keep in mind that just because it is normally enough, isn't good logic for introducing risk for no reason. That's why you make them larger by default, because there is risk to being small, not to being larger. It's all free, so just type a better number like /23 instead of /24 and voila, you've improved network safety with literally zero effort.
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@scottalanmiller said in Subnetting:
@wrcombs said in Subnetting:
we typically only use /24 because 253 (without network address/ broadcast address) host addresses are plenty for a 3 terminal 1 Server site.
Keep in mind that just because it is normally enough, isn't good logic for introducing risk for no reason. That's why you make them larger by default, because there is risk to being small, not to being larger. It's all free, so just type a better number like /23 instead of /24 and voila, you've improved network safety with literally zero effort.
Except in his case they have absolute control it is only a point-of-sale device net work
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@jaredbusch said in Subnetting:
@scottalanmiller said in Subnetting:
@wrcombs said in Subnetting:
we typically only use /24 because 253 (without network address/ broadcast address) host addresses are plenty for a 3 terminal 1 Server site.
Keep in mind that just because it is normally enough, isn't good logic for introducing risk for no reason. That's why you make them larger by default, because there is risk to being small, not to being larger. It's all free, so just type a better number like /23 instead of /24 and voila, you've improved network safety with literally zero effort.
Except in his case they have absolute control it is only a point-of-sale device net work
They do, at the moment. But things can change. No matter how safe it is today, one decision tomorrow and something totally safe today becomes a pain. Might as well just avoid it.
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@scottalanmiller said in Subnetting:
@wrcombs said in Subnetting:
but when the questions are "you need 4 networks which subnet mask would you use on this ip: 10.1.1.25"
That's gibberish. There's no way to know based on what is stated.
I probably missed the actual question.. but questions similar to that confuse me.
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@wrcombs said in Subnetting:
@scottalanmiller said in Subnetting:
@wrcombs said in Subnetting:
but when the questions are "you need 4 networks which subnet mask would you use on this ip: 10.1.1.25"
That's gibberish. There's no way to know based on what is stated.
I probably missed the actual question.. but questions similar to that confuse me.
It's all math and high school style word problems. It's all about "to meet the requirements", what options would you choose so that the sizes are correct.
