[comp.protocols.tcp-ip] To Subnet or not to subnet?

tep@tots.Logicon.COM (Tom Perrine) (01/04/91)

I am in the process of migrating our local Ethernet and Appletalk
networks into a coherent whole. The nets are currently not connected
to each other or to the Internet. (We are looking at a CERFnet
connection within 18 months, however.)

A long time ago, these nets were set up by various departments who
all knew that they were the only network we would ever have, and in
many cases used the network numbers that were the defaults, or used in
setup examples. (YECH!)

My plan is to have a single "backbone" which runs through all of our
buildings, with each "local" net attached to the backbone via a router
or a host acting as a gateway. (I know that a host acting as a gateway
is not efficient, but this is the hardware I have today.)

I already have four "local" nets identified, this number will probably
grow to about eight in the next 2 years. The largest local net has 12
hosts. It and one other net could easily grow to 20+ in the next two
years.

I have a single class-C network number assigned from the NIC.

Should I:

	1. subnet my already-registered class-C net?

	2. ask the NIC for four more class-C nets (for the local nets)
	and use the registered net for the backbone? (And register new
	nets as I need them?)

How scarce a resource are class-C net numbers?

Trying to be a good net-neighbor,
Tom Perrine (tep)                       |Internet: tep@tots.Logicon.COM
Logicon                                 |UUCP: sun!suntan!tots!tep
Tactical and Training Systems Division  |
San Diego CA                            |GENIE: T.PERRINE
"Harried: with preschoolers"            |+1 619 455 1330

henry@zoo.toronto.edu (Henry Spencer) (01/08/91)

In article <207@tots.UUCP> tep@tots.UUCP (Tom Perrine) writes:
>How scarce a resource are class-C net numbers?

Not very.  But routing-table slots to point to them are a bit more costly,
depending on who's doing your routing and how close they are to any fixed
limits in their software :-(.  In the long run, it would probably be best
for you to get a class-B network number -- sometimes easier said than done,
alas -- and subnet it.
-- 
If the Space Shuttle was the answer,   | Henry Spencer at U of Toronto Zoology
what was the question?                 |  henry@zoo.toronto.edu   utzoo!henry

tep@tots.Logicon.COM (Tom Perrine) (01/08/91)

Several days ago I sent a question regarding what to do about a
network number for our growing network. The options I listed were to
	1) subnet my existing class-C
	2) get additional class-C nets

The overwhelming response was choice 3! Of 10 responses, 8 suggested
that I what I really wanted was a class-B net, and most recommended
subnetting the thing as pseudo-class-C nets.

Thanks to all of the network wizards who replied:

dsinc.dsi.com!syd@ucsd.edu (Syd Weinstein)
barns@gateway.mitre.org (Bill Barns)
jnford@handlebar.weeg.uiowa.edu (Jay Ford)
uunet.UU.NET!delmarva!scoggin (John Scoggin)
brian@ucsd.EDU (Brian Kantor)
tecnet1.jcte.jcs.mil!kate
eng.xyplex.com!rlstewart (Bob Stewart)
jstewart@ccs.carleton.ca (John Stewart)
uunet.UU.NET!ccci!tcs (Terry Slattery)
henry@zoo.toronto.edu (Henry Spencer)

Tom Perrine (tep)                       |Internet: tep@tots.Logicon.COM
Logicon                                 |UUCP: sun!suntan!tots!tep
Tactical and Training Systems Division  |
San Diego CA                            |GENIE: T.PERRINE
"Harried: with preschoolers"            |+1 619 455 1330

fitz@wang.com (Tom Fitzgerald) (01/09/91)

henry@zoo.toronto.edu (Henry Spencer) writes:
> In the long run, it would probably be best
> for you to get a class-B network number -- sometimes easier said than done,
> alas -- and subnet it.

Why easier said than done?  Are class B addresses being rationed?

---
Tom Fitzgerald   Wang Labs        fitz@wang.com
1-508-967-5278   Lowell MA, USA   ...!uunet!wang!fitz

henry@zoo.toronto.edu (Henry Spencer) (01/10/91)

In article <ayylbj.4d@wang.com> fitz@wang.com (Tom Fitzgerald) writes:
>> In the long run, it would probably be best
>> for you to get a class-B network number -- sometimes easier said than done,
>> alas -- and subnet it.
>
>Why easier said than done?  Are class B addresses being rationed?

Not having tried it myself, I can't testify in detail, but my understanding
is that getting a class B can be a fair bit more difficult than getting a
handful of class Cs.
-- 
If the Space Shuttle was the answer,   | Henry Spencer at U of Toronto Zoology
what was the question?                 |  henry@zoo.toronto.edu   utzoo!henry

karl_kleinpaste@cis.ohio-state.edu (01/10/91)

henry@zoo.toronto.edu writes:
   Not having tried it myself, I can't testify in detail, but my understanding
   is that getting a class B can be a fair bit more difficult than getting a
   handful of class Cs.

From the NIC's NETINFO:INTERNET-NUMBER-TEMPLATE.TXT:

| 7) Unless a strong and convincing reason is presented, the network (if
| it qualifies at all) will be assigned a class C network number.  If a
| class C network number is not acceptable for your purposes state why.
| (Note: If there are plans for more than a few local networks, and more
| than 100 hosts, you are strongly urged to consider subnetting. [See RFC
| 950])

--karl