config
in e0
ip address 202.202.10.0 255.255.255.0
ip address 202.202.13.0 255.255.255.0 secondary
Might help..
----------
> From: Daryl Banttari <daryl@2ndlevel.net>
> To: ntisp@emerald.iea.com
> Cc: mknight@pce-inc.com
> Subject: Re: Netmask Question
> Date: Tuesday, May 06, 1997 12:26 PM
>
> Mark,
>
> You CANNOT use 255.255.254.0 in this case since the low subnet is not a
> multiple of two. The subnet mask is a bit mask: if you look at the
> third octet of your subnets bitwise they are 00001011 and 00001100.
> Since changes occur on bits 6, 7, and 8 of that byte, you cannot use a
> 11111110 subnet mask to combine them (that mask only allows host address
> changes in bit 8). If your subnet numbers were 207.240.12.0 and
> 207.240.13.0, you could supernet them together since the only bit that
> changes (12=00001100; 13=00001101) is the eighth bit. This is an
> oversimplification, but I'm not prepared to tech a course in binary
> arithmetic here :-)
>
> With your 2514, you can multihome so that the router will place both
> subnets on the same wire (and have two addresses on the interface) but
> that presents some interesting DHCP challenges, as I presume you've
> noticed. If you have an Ethernet switch you could do some interesting
> packet filtering to allow a single MS or Novell DHCP server grant
> addresses out of both subnets (by placing two NICs in the server and
> directing IP broadcasts from two sets of switch ports to exactly one
> interface in the DHCP server).. but... again, I exceed the scope of this
> list.
>
> What exactly is wrong with the status quo?
>
> Daryl
>
> Mark A. Knight wrote:
> >
> > I am using a Cisco 2514 as my default router, but, I do have IP
addresses from both Class Cs in on the same subnet. Does that mean I
should use the netmask of 255.255.254.0 as suggested by others. I'm not
really clear what you where saying.
> >
> > Mark A. Knight wrote:
> > >
> > > This is a basic IP netmask question, but, possibly the answer to a
few of the problems I am currently experiencing. If you have 2 or more
Class C addresses (e.g. 207.240.11.0 & 207.240.12.0) on the same network,
what should the netmask be?
> > > 255.255.255.0, 255.255.0.0?
>
>
> --
> +
> |Daryl S. Banttari, CNE
> |mailto:daryl@2ndlevel.net
> |http://www.2ndlevel.net/daryl
> |"Talk does not cook rice" - Chinese proverb
> |'Good things come to those who wait, but only the things left by
> | those who hustle.' - Abe Lincoln
> |'A candle loses nothing by lighting another candle' - Fr. James Keller
> |'There is a diminishing return on caution' - Me
> +
>
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