Jeff wrote:
> Also, is there a reason NOT to use 192.168 (which I always
> thought of as "Class C territory") in this way?
>

You should be fine. The 192.168 block is 192.168.0.0 through
192.168.255.255. It contains enough addresses for 256 classful Class-C
subnets, and that is where people usually assign "Class-C"ish private
subnets, but the entire 192.168 block is certainly available for your use.

On Sat, 26 Jan 2008, in the Usenet newsgroup comp.protocols.tcp-ip, in article
<6780c475-09ff-4968-91c1-02b8740f48f6@s19g2000prg.googlegroups.com>, Jeff wrote:

NOTE: Posting from groups.google.com (or some web-forums) dramatically
reduces the chance of your post being seen. Find a real news server.

>We currently have a basic LAN 192.168.0/24. We expect to grow past 253
>hosts in the next year or two, so want to make our network "bigger"

OK - that is done most easily by changing the mask on ALL systems on
this network. A /23 (255.255.254.0 or 0xffffe00) gives you a maximum
of 510 hosts, while a /22 (255.255.252.0 or 0xffffc00) gives you a
maximum of 1022 hosts. I'd be a bit leery of going any wider on a
single based on possible traffic density. What you need to look at
is "who is talking to who" and also the size of your switches.

>and let us do some subnetting in the future for various reasons.

Subnetting in the future is of little concern now. It means a router
to connect between subnets.

>So, here's what we're thinking: Changing the mask to 255.255.224.0
>will create a "192.168/19" network that will effectively give us
>eight subnets of 8190 each:

Those subnets might get awfully busy with 8000 hosts trying to talk
all at the same time. But there is nothing that requires you to
have the subnets in the same general address area. You can just as
easily have 1024 /22 subnets in the 172.16.0.0/12 range hanging off
a router, or if you want to go nuts - 16384 /22 subnets in the
10.0.0.0/8 range.

>We can then leave the servers routers and other important static IPs
>at the addresses they're at now with no "repointing" of various
>clients and apps to new locations, as long as those clients are in
>that first "main" range of addresses.

If all you are doing is changing the network mask, then nothing has
to change except for possibly cosmetic reasons (it looks prettier,
but otherwise makes absolutely no difference). Hosts on the other
networks can _probably_ use the same _servers_ but will have to know
the _local_ gateway address of the router. Ever look at the output
of the command /sbin/route -n on a *nix box? You'd likely see
something looking like

[example ~]$ /sbin/route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.0.0 0.0.0.0 255.255.254.0 U 0 0 89948 eth0
192.168.2.0 192.168.1.6 255.255.254.0 UG 0 0 32165 eth0
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 388 lo
0.0.0.0 192.168.1.248 0.0.0.0 UG 0 0 2673 eth0
[example ~]$

Here, there is the "local" LAN that this box is attached to, using
192.168.1.0/23. There is another subnet - 192.168.2.0/23, and if I
want to talk to it, I send my packets to the router at 192.168.1.6.
There is also a route "to the world" (which really means "everywhere
else") reachable via a router at 192.168.1.248. No mess, no fuss,
and all blindingly simple.

>Does that make sense or do I have a lot more reading up on subnetting
>to do? Also, is there a reason NOT to use 192.168 (which I always
>thought of as "Class C territory") in this way?

Only if you have more than 65000 systems give or take. In that case
you'll have to spill over into 172.16.0.0 - 172.31.255.255 (which
gives you another million addresses), or 10.0.0.0 - 10.255.255.255
(which gives you another 16.7 million). Your systems - do as you
wish. Just don't let those addresses be seen outside your bailiwick.
Your upstream may be using those addresses for their own nefarious
purposes, and you don't want to confuse things further.

Seriously - think about traffic density, as that may be a bigger
problem than merely making larger subnets.

Old guy

Thanks for all the good advice. Much appreciated.

Jeff

Moe Trin wrote:
> On Sat, 26 Jan 2008, in the Usenet newsgroup comp.protocols.tcp-ip,
> in article
> <6780c475-09ff-4968-91c1-02b8740f48f6@s19g2000prg.googlegroups.com>,
> Jeff wrote:
>
> NOTE: Posting from groups.google.com (or some web-forums) dramatically
> reduces the chance of your post being seen. Find a real news server.

While I agree google groups is far from the ideal UseNet posting and
reading client (especially in it's current form), I dont' think it's
right to tell anyone what to use. Everyone has personal preferences, he
may have a vail reason for using google - not all networks will allow
NNTP connections, like some corporate or school networks.

I don't like google groups as much as you and others, but I think it's
wrong to impose such a thing on others without any regard for any
potential valid reaons for using it.

On Mon, 28 Jan 2008, in the Usenet newsgroup comp.protocols.tcp-ip, in article
<606pmiF1pekosU1@mid.individual.net>, Steve K. wrote:

>Moe Trin wrote:

>> in article
>> <6780c475-09ff-4968-91c1-02b8740f48f6@s19g2000prg.googlegroups.com>,
>> Jeff wrote:
>>
>> NOTE: Posting from groups.google.com (or some web-forums) dramatically
>> reduces the chance of your post being seen. Find a real news server.
>
>While I agree google groups is far from the ideal UseNet posting and
>reading client (especially in it's current form), I dont' think it's
>right to tell anyone what to use.

That note is included by my news reader when I reply to articles
posted via groups.google.com It's put there to explain why posts
from google (and others) may not receive responses.

>Everyone has personal preferences, he may have a vail reason for using
>google - not all networks will allow NNTP connections, like some
>corporate or school networks.

I'm a network admin - I'm aware of those restrictions, which are normally
placed because of abuse. However, a few seconds searching with any
search engine will turn up lists of alternative or free news servers
many of which do have web interfaces.

>I don't like google groups as much as you and others, but I think it's
>wrong to impose such a thing on others without any regard for any
>potential valid reaons for using it.

I'm imposing nothing on anyone - I'm advising that there may be a limit
on the number who will see his post and why, while actually responding
to the content of his post.

Old guy