On Fri, 2009-01-09 at 16:56 -0800, Rick Stevens wrote: > No, the /24 covers EITHER 192.168.0.xxx or 192.168.1.xxx, but not both. > To treat both as a single network you need a /23 netmask. > > A netmask tells the system how many bits of the network address make up > the NETWORK part. This is where my misunderstanding was. > The remaining bits make up the host identifier. An > IPV4 address is 32 bits. A /24 (or 255.255.255.0) netmask says the > first 24 bits (the first three octets) make up the network part. What then, is a sub-net? > In my > graphic below, the netmask stuff is shown in by "x"s and the bits under > the "x"s make up the network address: > > netmask: xxxxxxxx.xxxxxxxx.xxxxxxxx.-------- (255.255.255.0 /24) > binary addr: 11000000.10101000.00000000.00000001 (192.168.0.1) > binary addr: 11000000.10101000.00000001.00000001 (192.168.1.1) > > So you can see that they're separate networks. Now, with a /23 netmask: > > netmask: xxxxxxxx.xxxxxxxx.xxxxxxx-.-------- (255.255.254.0 /23) > binary addr: 11000000.10101000.00000000.00000001 (192.168.0.1) > binary addr: 11000000.10101000.00000001.00000001 (192.168.1.1) > > You can see here that they're the same network now, and you're using 9 > bits as the host identifier. Okay, for a small private network of up to 2 dozen boxes, is there a standard or convention for selecting the final numbering system, eg 192.168.0.101 to 125 vs 192.168.9.1 to 25 ? Is there a need to distinguish between computer,printer or router in the numbering heirarchy? > > Also note that the netmask must be consecutive 1 bits...the first 0 bit > marks the end of the netmask. 255.255.254.0 is OK (the last octet is > 11111110 binary), but 255.255.253.0 isn't (the last octet is 11111101) > and would be treated the same as 255.255.255.252 (a /22 or 11111100). > > Does it make sense now? Getting there! -- Hooroo, Simon Registered Linux User #463789. Be counted at: http://counter.li.org/ -- fedora-list mailing list fedora-list@xxxxxxxxxx To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
