Changing subnet mask?
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 @dashrender said in Changing subnet mask?: @scottalanmiller said in Changing subnet mask?: @siringo said in Changing subnet mask?: I know the subnets are different, but with all devices having 10.0.0.x addresses I'm thinking they still may be seen by the /24 devices???? Yes, if everything falls within the scope of a /24, then all of the devices that are in a larger pool will keep working. But they ALL have to be already in the smaller pool and ONLY the subnet mask gets changed. But again... why? Forgetting about the - but why part... The OP could make sure all devices are in the /24 before touching anything by changing DHCP to only hand out addresses in /24 range, then move by hand any staticly assigned devices into that range. Yes, quite doable. 
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 @dashrender said in Changing subnet mask?: @scottalanmiller said in Changing subnet mask?: @siringo said in Changing subnet mask?: I know the subnets are different, but with all devices having 10.0.0.x addresses I'm thinking they still may be seen by the /24 devices???? Yes, if everything falls within the scope of a /24, then all of the devices that are in a larger pool will keep working. But they ALL have to be already in the smaller pool and ONLY the subnet mask gets changed. But again... why? Forgetting about the - but why part... The OP could make sure all devices are in the /24 before touching anything by changing DHCP to only hand out addresses in /24 range, then move by hand any staticly assigned devices into that range. I gave that process above. 
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 @irj said in Changing subnet mask?: @siringo said in Changing subnet mask?: @dashrender said in Changing subnet mask?: Then comes the question - does he have the gear needed to do that? the answer is no, the answer to whether I have the desire or need is also no. That's a very sad answer IMO sorry to have disappointed you  
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 @dashrender said in Changing subnet mask?: @travisdh1 said in Changing subnet mask?: @jaredbusch said in Changing subnet mask?: @travisdh1 said in Changing subnet mask?: You're conflating VLANs with security. You need to realize who you are talking to. @IRJ is probably the most skilled security person on the community. I know this, and statements like he made give me headaches after having to explain to other people that VLAN does nothing for security if you don't have firewall/access rules as well. The types of places @IRJ has worked at, I agree that it would be insane to have a flat network. This is my thoughts - most small businesses don't need/want more complexity than a flat network. ^^^ real world. 
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 @scottalanmiller said in Changing subnet mask?: @siringo said in Changing subnet mask?: Inherited an old SBS network which has been upgraded, but is still using the 10.0.0.0 /8 setup. 
 I was thinking of changing the subnet to /24.while the old addressing is insane, what's the reason to change? Unless there is a benefit, why? Just reducing the address pool isn't going to buy you anything. Yes this ^^^ exactly Scott. I'm of the same mind, that's part of why I threw the question out there, I wanted 2nd opinions. Everything is working fine ATM, why would I want to make an unneccessary change that provided no benefit but could introduce downtime. I susbcribe heavily to the KISS principal, hence my lack of interest in VLANing in this instance. The only reason I came up with, when thinking about the change is that it may make the environment 'look' more professional by having a more appropriately scoped, network. Thanks for all the opinions and information it is all greatly appreciated. 


