Re: Fw: Re: Network Address/Netmask Notation
On Tue, 25 Mar 2003 22:10:54 -0800 (PST) Keith Morse [EMAIL PROTECTED] wrote: On Sun, 23 Mar 2003, David A. Bandel wrote: With non-VLSM CIDR, we can't use /#. We will also get very large headaches trying to calculate which IPs are found on a network with absurd netmasks like 255.255.255.123. If you don't think this is valid, you can try it on your network and see that it works just fine with the following values: network: 192.168.0.1 netmask: 255.255.255.123 broadcast: 192.168.0.133 hosts: 192.168.0.5, 192.168.0.129 yes, for this particular netmask, there are only 2 hosts, other non-VLSM netmasks give varying numbers of hosts in different patterns scattered about between the network and broadcast numbers. Wild, I've never seen non-contigous netmasks before. Is this legal per the ip specifiation, or just the result of the xor/nor (sorry don't remember the boolean operation involved between ip and netmask) operation? This is 100% in accordance with the RFCs (not sure which one(s), perhaps 1518 and/or 1519). Been a while since I actually read them. And it's AND for IP/Netmask. Ciao, David A. Bandel -- Focus on the dream, not the competition. Nemesis Racing Team motto pgp0.pgp Description: PGP signature ___ Linux-users mailing list [EMAIL PROTECTED] Unsubscribe/Suspend/Etc - http://www.linux-sxs.org/mailman/listinfo/linux-users
Re: Fw: Re: Network Address/Netmask Notation
On Sun, 23 Mar 2003, David A. Bandel wrote: With non-VLSM CIDR, we can't use /#. We will also get very large headaches trying to calculate which IPs are found on a network with absurd netmasks like 255.255.255.123. If you don't think this is valid, you can try it on your network and see that it works just fine with the following values: network: 192.168.0.1 netmask: 255.255.255.123 broadcast: 192.168.0.133 hosts: 192.168.0.5, 192.168.0.129 yes, for this particular netmask, there are only 2 hosts, other non-VLSM netmasks give varying numbers of hosts in different patterns scattered about between the network and broadcast numbers. Wild, I've never seen non-contigous netmasks before. Is this legal per the ip specifiation, or just the result of the xor/nor (sorry don't remember the boolean operation involved between ip and netmask) operation? Note: since I'm not a masochist and don't like headaches (or anding binary netmasks w/ addresses), I use a program to calculate the above just as the kernel does. Ciao, David A. Bandel ___ Linux-users mailing list [EMAIL PROTECTED] Unsubscribe/Suspend/Etc - http://www.linux-sxs.org/mailman/listinfo/linux-users
Fw: Re: Network Address/Netmask Notation
Ugg, forget that. It was too early to think. What I gave was for x.x.x.x/16 Begin forwarded message: Date: Sun, 23 Mar 2003 08:09:23 -0800 From: Vern W Heesch [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Re: Network Address/Netmask Notation You are correct that the first 2 octets are for network number, which leaves the last 2 octets for hosts. So the range of useable host addresses are 192.168.0.1 - 192.168.255.254 with a netmask of 255.255.0.0 On Sun, 23 Mar 2003 10:54:54 -0500 Kurt Wall [EMAIL PROTECTED] wrote: Hi, list, I've never been terribly clear on this, so I'll ask here. Given a network address of, say, 192.168.0.0 and a netmask of /8, thus 192.168.0.0/8, this means that 8 bits of the network address will be used for the host address, which means that any address in the range 192.168.0.1 - 192.168.0.255 will match. Am I correct? Thanks, Kurt -- When you are in it up to your ears, keep your mouth shut. ___ Linux-users mailing list [EMAIL PROTECTED] Unsubscribe/Suspend/Etc - http://www.linux-sxs.org/mailman/listinfo/linux-users ___ Linux-users mailing list [EMAIL PROTECTED] Unsubscribe/Suspend/Etc - http://www.linux-sxs.org/mailman/listinfo/linux-users
Re: Fw: Re: Network Address/Netmask Notation
On Sun, 23 Mar 2003 08:13:38 -0800 Vern W Heesch [EMAIL PROTECTED] wrote: Ugg, forget that. It was too early to think. What I gave was for x.x.x.x/16 Yep. And I was just about to answer that. For those of you who have been around networking for less than about 10 years, we didn't always use VLSM (variable length subnet masking), which as I said is a subset of CIDR (classless inter-domain routing). We used to use classful routing which is still built into ifconfig: class A: first octet 0-127 (netmask 255.0.0.0) class B: first octet 128-191 (netmask 255.255.0.0) class C: first octet 192-223 (netmask 255.255.255.0) class D: first octet 224-254 (experimental block, 224.x.x.x now used for multicast for those paying close attention) while the above is obsolete, if you configure an address like 64.116.181.3/29 (netmask 255.255.255.248), you must specify the broadcast address or ifconfig will assume a broadcast address of 64.255.255.255. Obviously incorrect, since our broadcast address is 64.116.181.7. Now VLSM is nice because it allows us to split things up neatly between network and host addresses, the first non-255 octet being one of 0, 128, 192, 224, 240, 248, or 252 (or 254 if the second or third, but not last, octet). With VLSM we can use the /# notation. (Yes, I'm ignoring the special case /32). With non-VLSM CIDR, we can't use /#. We will also get very large headaches trying to calculate which IPs are found on a network with absurd netmasks like 255.255.255.123. If you don't think this is valid, you can try it on your network and see that it works just fine with the following values: network: 192.168.0.1 netmask: 255.255.255.123 broadcast: 192.168.0.133 hosts: 192.168.0.5, 192.168.0.129 yes, for this particular netmask, there are only 2 hosts, other non-VLSM netmasks give varying numbers of hosts in different patterns scattered about between the network and broadcast numbers. Note: since I'm not a masochist and don't like headaches (or anding binary netmasks w/ addresses), I use a program to calculate the above just as the kernel does. Ciao, David A. Bandel -- Focus on the dream, not the competition. Nemesis Racing Team motto pgp0.pgp Description: PGP signature ___ Linux-users mailing list [EMAIL PROTECTED] Unsubscribe/Suspend/Etc - http://www.linux-sxs.org/mailman/listinfo/linux-users
