[NTLUG:Discuss] IP super/sub-netting maddness

[joseph beasley]

255.255.255.200 is not a valid subnet mask.  255.255.255.192 or
255.255.255.224.  Just follow the bits.

--- Wayne Walker <wwalker at bybent.com> wrote:

> In theory, you could use 255.255.255.200 and 192.168.1.64.
> 
> BUT, why do you need to refer to those machines as a subnet?  For
> firewall rules?
> 
> If so, just treat it as two 26 bit subnets.
> 
> 192.168.1.64/26  255.255.255.192
> 192.168.1.128/26 255.255.255.192
> 
> Wayne
> 
> On Tue, Sep 19, 2006 at 02:18:06PM -0500, Richard Geoffrion wrote:
> > Ok... I think I'm asking the impossible here because no matter how
> I 
> > calculate it the bits don't line up...but here goes. 
> > 
> > Can you supernet multiple subnetted network ranges when they don't
> fall 
> > on bit boundaries??
> > 
> > For instance, 
> > 
> > Networks 192.168.0.0 mask 255.255.255.0 and 192.168.1.0 mask 
> > 255.255.255.0 can be referred to / supernetted  by changing the
> mask to 
> > 255.255.254.0.  This gives 510 available hosts on the same network 
> > instead of just 254.
> > 
> > 
> > Now... what about a situation where I have a 125 ip address DHCP
> scope 
> > on a 192.168.1.0/24 segment...and (in my infinite wisdom and
> foresight) 
> > I started it at 60.  Yes... 60. Just pick a number...ANY number. 
> Throw 
> > a dart -- WHOO HOO!  Triple 20!   The DHCP scope is
> 192.168.1.60-185.
> > 
> > Now that the DHCP scope is set.. let's put servers and other
> special 
> > statics from 1-47 and printers from 224-254... YEAH!! Let's just
> trash 
> > both /25 subnets with 'stuff' we can't move.
> > 
> > Now that we have all our static hosts and printers integrated...
> .how 
> > about we firm up these ranges (which is where I got those numbers
> above) 
> > and see if there is a way to reference the DHCP scope by network.  
> > Hmmm... nope.. BUT.. if I modify the dhcp scope to 
> > be...192.168.1.64-192....then the DHCP scope will fall on the
> ranges of 
> > several subnets.
> > 
> > So...is it possible to supernet the subnets?  (I know it sounds 
> > ridiculous...and unlikely...but if it's possible it would be a
> great 
> > learning experience for me...not to mention making firewall rules 
> > easier. :) )
> > 
> > Afterthought...  In the history of TCP/IP...has a subnet mask such 
> > as........well...no...that'd be an invalid subnet mask.  hm...
> still... 
> > has something like (11111111.11111111.11111111.1101xxxx)
> 255.255.255.200 
> > ever been used?
> > 
> > -- 
> > Richard
> > Nope...I'm not smoking anything....
> > (not to say I'm not crazy...just not smok'n)
> > 
> > 
> > _______________________________________________
> > http://www.ntlug.org/mailman/listinfo/discuss
> 
> -- 
> 
> Wayne Walker
> 
> www.unwiredbuyer.com - when you just can't be by the computer
> 
> wwalker at bybent.com                    Do you use Linux?!
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> 
> _______________________________________________
> http://www.ntlug.org/mailman/listinfo/discuss
> 


Joe Beasley
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