hello all, we are almost out of ip addresses our internet network is 192.168.2. s/m 255.255.255.0 basically there is 252 ip addresses right leave out 1 for broadcast and 1 for network. I found a post on this it talked about super netting 255.255.240.0 ? which will give you 500 ip addresses question is that a brand new 500? or just another 252? also what affect does this have on switches and firewalls do we have to add static routes for the network to know the new subnet? other solution how about just creating another scope we can use 192.168.9.0 subnet and keep the 255.255.255.0 s/m. thanks for replying, please give examples

You will get up to 500 addresses. You will have to change all computers/firewalls/routers to have the new subnet mask. If you add a new scope, it won't work right unless you are on separate sides of a router.

If you have two subnets, they need to be separated by a router. Such as if I have a 192.168.1.0/24 and 192.168.2.0/24 then i would have to have one of those on interface 1 of the router and then the second on interface 2 of the router in order for them to communicate together. The router would block all broadcast traffic, so you would need to have two DHCP servers, one for each subnet.

separate sides of a router what do you mean?

If you have two subnets, they need to be separated by a router. Such as if I have a 192.168.1.0/24 and 192.168.2.0/24 then i would have to have one of those on interface 1 of the router and then the second on interface 2 of the router in order for them to communicate together. The router would block all broadcast traffic, so you would need to have two DHCP servers, one for each subnet.

ok let me step back for a second and ask whats the best way to handle running out of ip addresses, whats the best solution that will not cause major network change? whats the easiest way to add more ip addresses without major network change?

It would probably be easiest to use a different subnet mask. Change it on the DHCP Server and then update it manually on the servers and routers (or anything with a static address).

Hi, Thank you for the post. When you re-subnet your DHCP scope, you must first deleted DHCP scope and then re-created using the new subnet mask. Here is a sample to reconfigure DHCP scope subnet mark with command. http://www.windowstricks.in/2009/06/how-to-change-subnet-mask-of-dhcp-scope.html If there are more inquiries on this issue, please feel free to let us know. RegardsRick Tan TechNet Community Support

yup that what I came up with after reading the article from the other post about the same issue. http://articles.techrepublic.com.com/5100-10878_11-5034906.html this is the direction we are probably going to go in. current ip 192.168.2.0 s/m 255.255.255.0 change s/m to 255.255.252.0 which will give us 1022. The thing is we currently have remote sites that we have a vpn tunnel too. So the 192.168.0 network we can use. the 192.168.1.0 is the subnet of one of our remote sites we probably going to reserve those numbers. The 192.168.2.0 network we currently are using and almost out of ip addresses. The 192.168.3.0 network is currently our ip phone network (vlan on switch) we will leave that as is. Any static ip we will have to change the s/m to 255.255.252.0 my question how about the default gateway? it is currently 192.168.2.254 I am thinking that has to go to the 192.168.0.0 or 0.0? question so basically I have 4 networks under one subnet, CIDR is cool I like it

You could use 172.16.x.x /16 This will give you 65,000 some addresses.

Hi, it is currently 192.168.2.254 I am thinking that has to go to the 192.168.0.0 or 0.0? It's okay to keep your current gateway ip address or change it to 192.168.0.1. It means you could set up any ip or first ip to be the gateway in your network subnet. RegardsRick Tan TechNet Community Support

thats good to know so basically I just need to change my s/m on all the static entries.

ok I have to ask, we currently have two subnets on our network the 192.168.2 and the 192.168.3 the .3 network is for the phones. and it is separated by vlan on the level 3 switch. The dhcp is handing out ip addresses to the ip phones and it is separated by vlan why not add another subnet to dhcp ? put that ip address on the switch as a vlan example 192.168.9.0 will it not become part of the pool of the ip addresses available?

You'll not be able to connect the two subnets together without a router. If you want to keep them separate, then i'd put them in different VLANs

You'll not be able to connect the two subnets together without a router. If you want to keep them separate, then i'd put them in different VLANs

I looked at my firewall, we have e0/0 with an outside ip address, e0/1 with the 192.168.2.1 the e0/2 is shutdown, int e0/3 is shutdown. can I go the route of assigning internal ip addresses to those int example e0/2 192.168.9.0 create a dhcp scope, create a vlan on the switch I am thinking that should work?

It should work, just make sure that your firewall will support that.

ok guys revising this again. just way too painful to think of the other option of firewall/router, switch, servers and network printers have to change each one ugh! ok how about this, the firewall/route, switch, servers and network printers keep the .2.x network. and we add a .20.x to .23.x and use cidr for the s/m? and add static routes where need be on the router and switch, I have seen this before where the major appliances are one network and the pc and phones are on another. my knowledge on this says static route, but I'm not sure, any ideas?