Re: [CentOS] Subnet expansion
On 7/28/11 5:47 AM, Fajar Priyanto wrote: Hi John, Thanks for helping. I have some discussion also with friends in the physical world, and they suggest: 1. Keep the current network 10.1.16.0/22 2. Create another network 10.1.20.0/22 (half static, half dhcp) 3. Setup a router so that the two network can talk to each other. 4. This will offer no disruption to the current network setup at all. That will work - just like any other physically separate subnets. If your existing gateway router has an extra interface, just connect there. You can also use VLANs to make what will act like separate subnets use the same physical wire if your network equipment supports it. One issue that I see may be coming is that, since I want to allocate 10.1.20.0/22 to a specific VM that belong to a specific team, I may have to setup the DHCP based on MAC. Could be very tedious. You could use separate DHCP servers on each subnet, or configure the router to relay to one server (ip-helper address on a Cisco). The DHCP server will know the subnet origin from a relayed request and can reply accordingly. -- Les Mikesell lesmikes...@gmail.com ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Subnet expansion
From: Fajar Priyanto fajar...@arinet.org Currently I have this network: 10.1.16.0/22. 10.1.16.0-10.16.17.254 are DHCP managed 10.1.18.0-10.1.19.254 are statically assigned If I need to expand it to: 10.1.16.0/20 1. What is the best way to do it with minimal network disruption? I am no subneting pro but: Currently you have half DHCP and half statics... How will it be with the /20? Still half/half? $ ipcalc -nb 10.1.16.0/20 Address: 10.1.16.0 Netmask: 255.255.240.0 = 20 Wildcard: 0.0.15.255 = Network: 10.1.16.0/20 HostMin: 10.1.16.1 HostMax: 10.1.31.254 Broadcast: 10.1.31.255 Hosts/Net: 4094 A /20 half/half would give: 10.1.16.1-10.1.23.254 10.1.24.1-10.1.31.254 2. If I keep some machine with 22 subnet mask, will it still be able to talk to the other machines in it's range? They would talk to 10.1.16.1-10.1.19.254 ones, but would go for the gateway for 10.1.20.1-10.1.31.254 JD ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Subnet expansion
On Tue, Jul 26, 2011 at 7:53 PM, John Hodrien j.h.hodr...@leeds.ac.uk wrote: Currently I have this network: 10.1.16.0/22. 10.1.16.0-10.16.17.254 are DHCP managed 10.1.18.0-10.1.19.254 are statically assigned If I need to expand it to: 10.1.16.0/20 I think the answer to this part is not trivially. A machine in the /20 subnet will expect to be able to talk directly to a machine within the /22, but that machine will want to talk via a router. You can hide subnets within subnets using arp-proxying, but I'm not sure there's an easier way. A machine within the /22 would be able to talk to any other machine within that /22 (even if they're configured to use /20), but won't be able to happily talk to machines within the /20 but outside of the /22. Hi John, Thanks for helping. I have some discussion also with friends in the physical world, and they suggest: 1. Keep the current network 10.1.16.0/22 2. Create another network 10.1.20.0/22 (half static, half dhcp) 3. Setup a router so that the two network can talk to each other. 4. This will offer no disruption to the current network setup at all. One issue that I see may be coming is that, since I want to allocate 10.1.20.0/22 to a specific VM that belong to a specific team, I may have to setup the DHCP based on MAC. Could be very tedious. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Subnet expansion
On 7/28/11 4:18 AM, John Doe wrote: 2. If I keep some machine with 22 subnet mask, will it still be able to talk to the other machines in it's range? Linux boxes seem to mostly work with the wrong netmask, but I've seen things that don't. Your subnet broadcast will be wrong. They would talk to 10.1.16.1-10.1.19.254 ones, but would go for the gateway for 10.1.20.1-10.1.31.254 But the gateway may send an icmp redirect, knowing you should be able to reach the target directly. I'd recommend fixing everything to match as soon as possible. -- Les Mikesell lesmikes...@gmail.com ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Subnet expansion
On Tue, 26 Jul 2011, Fajar Priyanto wrote: Hi all, Can pls share your experience on this? Currently I have this network: 10.1.16.0/22. 10.1.16.0-10.16.17.254 are DHCP managed 10.1.18.0-10.1.19.254 are statically assigned If I need to expand it to: 10.1.16.0/20 1. What is the best way to do it with minimal network disruption? 2. If I keep some machine with 22 subnet mask, will it still be able to talk to the other machines in it's range? Seeing as noone else has posted anything, you can have my thoughts. I think the answer to this part is not trivially. A machine in the /20 subnet will expect to be able to talk directly to a machine within the /22, but that machine will want to talk via a router. You can hide subnets within subnets using arp-proxying, but I'm not sure there's an easier way. A machine within the /22 would be able to talk to any other machine within that /22 (even if they're configured to use /20), but won't be able to happily talk to machines within the /20 but outside of the /22. jh ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
