How would changing my subnet mask change my local network.

[SuperCookie78]

In the coming months i plan to installing and setting up multiple servers for my home. I would like to have the servers on static local ips for organization. Lets say i wanted my servers on 192.168.0.x, normal devices on 192.168.1.x,  secondary devices and IoT on 192.168.2.x and guest devices on 192.168.3.x. Is that possible if i change my subnet mask from 255.255.255.0 to 255.255.0.0? and if it is are there any down sides to doing so?

 

I am a networking noob so I am sorry if this is bad question.

[YoFavRussian]

24 minutes ago, SuperCookie78 said:

In the coming months i plan to installing and setting up multiple servers for my home. I would like to have the servers on static local ips for organization. Lets say i wanted my servers on 192.168.0.x, normal devices on 192.168.1.x,  secondary devices and IoT on 192.168.2.x and guest devices on 192.168.3.x. Is that possible if i change my subnet mask from 255.255.255.0 to 255.255.0.0? and if it is are there any down sides to doing so?

 

I am a networking noob so I am sorry if this is bad question.

This is a bit difficult to explain directly. you can do what you want to do but I believe what you're looking to do is have 192.168.X be your network portion of the address and the last octet be your host portion giving you a total of 254 usable addresses per network. 255.255.255.0 would still be your subnet mask, but you need to route between networks.

 

If I learned anything from Cisco, Routers connect networks.

 

A subnet mask defines your network portion and seperates it from the host portion.

Even if you were to subnet by "Borrowing bits" from the host portion, you would still need a router to route between the networks.

 

so changing it would just change the logical AND

192.168.1.24

255.255.255.0

11000000.10101000.00000001.00011000

11111111.11111111.11111111.00000000

ANDED 11000000.10101000.00000001.00000000

 

192.168.1.24

255.255.0.0

11000000.10101000.00000001.00011000

11111111.11111111.00000000.00000000

ANDED 11000000.10101000.00000000.00000000

[Electronics Wizardy]

Instead of making one big subnet, id make multiple smaller /24s and have a l3 switch or router route between them.  Then you can control the traffic between the subnets and limit broadcast traffic.

[YoFavRussian]

8 minutes ago, Electronics Wizardy said:

Instead of making one big subnet, id make multiple smaller /24s and have a l3 switch or router route between them.  Then you can control the traffic between the subnets and limit broadcast traffic.

Agreed, keep the 255.255.255.0 subnet mask and just create individual /24 networks and have either a level 3 switch or a router that routes between them. And like he said, it will break up the broadcast traffic.

 

Do L3 switches forward broadcasts, I know routers don't but I can't recall if a L3 switch does or not.

[Electronics Wizardy]

Just now, YoFavRussian said:

Do L3 switches forward broadcasts, I know routers don't but I can't recall if a L3 switch does or not.

you can configure it on the switch/router.

 

One thing is if you block broadcasts some programs won't work across subnets as they use that to find other systems on the network.

[YoFavRussian]

1 minute ago, Electronics Wizardy said:

you can configure it on the switch/router.

 

One thing is if you block broadcasts some programs won't work across subnets as they use that to find other systems on the network.

From what I was taught, by default routers won't, and switches would. was wondering what a L3 switch did by default.

[Electronics Wizardy]

Just now, YoFavRussian said:

From what I was taught, by default routers won't, and switches would. was wondering what a L3 switch did by default.

switches won't send broadcast packets between subnets. Thats why you make different subnets. I think a l3 switch can, but depends on model.

 

 

[YoFavRussian]

A Cisco switch by default will forward a broadcast out all ports except the one it came in on. And if another switch gets it it'll do the same. Unless you subnet like you said.

[Electronics Wizardy]

Just now, YoFavRussian said:

A Cisco switch by default will forward a broadcast out all ports except the one it came in on. And if another switch gets it it'll do the same. Unless you subnet like you said.

all ports on the same vlan. If you want subnets, you need to put each subnet in its own vlan.

[SuperCookie78]

1 hour ago, YoFavRussian said:

This is a bit difficult to explain directly. you can do what you want to do but I believe what you're looking to do is have 192.168.X be your network portion of the address and the last octet be your host portion giving you a total of 254 usable addresses per network. 255.255.255.0 would still be your subnet mask, but you need to route between networks.

 

If I learned anything from Cisco, Routers connect networks.

 

A subnet mask defines your network portion and seperates it from the host portion.

Even if you were to subnet by "Borrowing bits" from the host portion, you would still need a router to route between the networks.

 

so changing it would just change the logical AND

192.168.1.24

255.255.255.0

11000000.10101000.00000001.00011000

11111111.11111111.11111111.00000000

ANDED 11000000.10101000.00000001.00000000

 

192.168.1.24

255.255.0.0

11000000.10101000.00000001.00011000

11111111.11111111.00000000.00000000

ANDED 11000000.10101000.00000000.00000000

So yes i am looking for 192.168.x.x. So how would i go about doing that.

[Electronics Wizardy]

28 minutes ago, SuperCookie78 said:

So yes i am looking for 192.168.x.x. So how would i go about doing that.

what router?

 

Really, just amke more subnets, id stay away from one big /16

 

otherwise just change the router to a /16

[mynameisjuan]

1 hour ago, Electronics Wizardy said:

limit broadcast traffic

That will never be a problem on a home network

1 hour ago, Electronics Wizardy said:

If you want subnets, you need to put each subnet in its own vlan

You can have as many subnets per VLAN as you want

1 hour ago, Electronics Wizardy said:

you can configure it on the switch/router.

One thing is if you block broadcasts some programs won't work across subnets as they use that to find other systems on the network.

1. You can only configure IP helpers to forward broadcast

2. Blocking broadcast will not break anything on another network

1 hour ago, YoFavRussian said:

Do L3 switches forward broadcasts, I know routers don't but I can't recall if a L3 switch does or not.

Depends on broadcast type

1. Broadcast frame within VLAN - yes

2. Broadcast packet between subnets - no

3. Broadcast packet with IP helper between subnets - yes

[SuperCookie78]

12 minutes ago, Electronics Wizardy said:

what router?

 

Really, just amke more subnets, id stay away from one big /16

 

otherwise just change the router to a /16

well right now internet first comes in and our Fios Quantum Gateway acts as a modem. the fios router then puts out 2.4G and 5G wifi and its built in switch is connected to my main desktop (currently out of order), a temporary freenass server and other computers through Ethernet. one of those Ethernet ports goes to an Asus router in acess point mode that is setup to output the same SSID for 2.4G and 5G  wifi so we can have full coverage of our house.

 

When i setup the servers i would like to have fios router in the same setup but all ethernet connections going through a rack mounted switch that may or may not have 10gig for the servers. 

[Electronics Wizardy]

Just now, SuperCookie78 said:

well right now internet first comes in and our Fios Quantum Gateway acts as a modem. the fios router then puts out 2.4G and 5G wifi and its built in switch is connected to my main desktop (currently out of order), a temporary freenass server and other computers through Ethernet. one of those Ethernet ports goes to an Asus router in acess point mode that is setup to output the same SSID for 2.4G and 5G  wifi so we can have full coverage of our house.

 

When i setup the servers i would like to have fios router in the same setup but all ethernet connections going through a rack mounted switch that may or may not have 10gig for the servers. 

If you want to seprate the devices, id get a different router that support subnets, like pfsense, then make vlans and split up the different devices.

 

If you don't want to seperate the device on the network, and don't have more than 254 devices, id just keep the /24.

[SuperCookie78]

4 minutes ago, Electronics Wizardy said:

If you want to seprate the devices, id get a different router that support subnets, like pfsense, then make vlans and split up the different devices.

 

If you don't want to seperate the device on the network, and don't have more than 254 devices, id just keep the /24.

so your saying i have an excuse to build a pfsense router?

[Electronics Wizardy]

Just now, SuperCookie78 said:

so your saying i have an excuse to build a pfsense router?

I mean if you want to mess with network its a good start. Most home routers don't let you create multiple sub nets.

[SuperCookie78]

28 minutes ago, Electronics Wizardy said:

I mean if you want to mess with network its a good start. Most home routers don't let you create multiple sub nets.

also why would a router give you the option to change the subnet mask but only let you connect 254 devices to it?

[mynameisjuan]

8 minutes ago, SuperCookie78 said:

also why would a router give you the option to change the subnet mask but only let you connect 254 devices to it?

There are no limits to number of devices connected, subnet wise. You connect until memory is full

[SuperCookie78]

Just now, mynameisjuan said:

There are no limits to number of devices connected, subnet wise. You connect until memory is full

so i tried changing the subnet mak to 255.255.0.0 and it allowed me to do so. but when i tried changing the start and end ip to include more than 254 devices it said no.

[mynameisjuan]

1 minute ago, SuperCookie78 said:

the start and end ip

What start and end IP were you using?

Also are you sure you are not changing DHCP only?

[SuperCookie78]

Just now, mynameisjuan said:

What start and end IP were you using?

default is

Start:

192.168.1.2 (1.1 is reserved for the router)

End:

192.168.1.254

 

What i tried was

Start:

192.168.1.2

End

192.168.4.255

 

it then spits out this error

"The number of IP Addresses in the DHCP IP address range must not be more than 256."

[mynameisjuan]

2 minutes ago, SuperCookie78 said:

The number of IP Addresses in the DHCP IP address range must not be more than 256.

Did you change the IP/mask on your LAN side?

[YoFavRussian]

3 minutes ago, mynameisjuan said:

Did you change the IP/mask on your LAN side?

Could the fact that he's using 4.255 cause it, since 255 is the broadcast?

[SuperCookie78]

1 minute ago, YoFavRussian said:

Could the fact that he's using 4.255 cause it, since 255 is the broadcast?

i tried 254 and same error.

[mynameisjuan]

4 minutes ago, YoFavRussian said:

Could the fact that he's using 4.255 cause it, since 255 is the broadcast?

.255 is not always a broadcast address. 

 

192.168.1.0/24 - 1.255 is a broadcast

192.168.1.0/25 - 1.127 is the broadcast