I have to disagree, asking for a whole class C for one or
possibly two addresses is egregious use of address space. Either
subnet the class C (as discussed in an earlier posting) or, if the
firewall can do address translation, use the class C for the network
between your firewall and your ISP or your router, and one of the
reuseable networks behind your firewall.
On Tue, 13 Aug 1996 15:28:11 -0400, the sage Capital Works Webmaster
>Ben Goodyear wrote:
>> > I'm sure that this is blindingly obvious, but I have not been able to find any
>> > references to it...
>> > I have a class C address for my network - As part of my firewall I will have a
>> > dual homed sparc 5 running Solaris 2.5. I want to forward packets from one
>> > interface to the other - am I allowed to use netmask 255.255.255.0 with both
>> > interfaces in the same subnet e.g.
>> > 126.96.36.199 and the other on 188.8.131.52
>> > I have tried to set routing up for this up and failed so the question is
>> > Do I have to subnet a class C address to achieve packet forwarding or is there
>> > some trick in the routing that I am missing??
>> > All the references on this soft of setup assume that you are doing packet
>> > forwarding from something like 184.108.40.206 to 220.127.116.11, but I only have a
>> > class C from my ISP and cannot affort to loose the half my IP addresses that
>> > subnetting would cause.
>> > Paul.
>> > --
>> Yes you do have to use subnetting to implement routing on a single
>> class "c" address.
>> To route between two networks, the two networks have to have a
>> different network number (or else, how would it know when to route?).
>> To get different network numbers on a class "c" you have to use
>> use subnet 255.255.255.192
>> this will give you four networks of 64 hosts:
>> x.x.x.0-63, x.x.x.64-127, x.x.x.128-191, x.x.x.192-255
>> Set one interface to: 18.104.22.168
>> Set the other to: 22.214.171.124
>Avoid the whole thing! Get one additional address from your ISP, on the
>same address subnet as your router! -unless- if your router is
>configured on your class 'C', then have your ISP provide you with a
>unique IP for the router and then do a by-the-way-request for an
>additional one for your firewall? Thus avoiding the masking issue.
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