lapyun@smosjc.UUCP (Lap Yun Yau) (04/25/91)
We just registered our Internet address and are now planning for reorganizing
of all networks within the company.
The following scheme shows the relationship of nets and subnets:
====+====================+=============== Backbone Network
| |
|Dept A |Dept B
=+==+==+==+= ==+==+==+==+==o==o=== Departmental Networks
| | | | | | | | (=o= node)
| | | =+==== | | | =+=====Net B.1 Dept Subnet 1
| | =+===== | | =+=====Net B.2 Dept Subnet 2
| =+===== | =+=====Net B.3 Dept Subnet 3
=+===== =+=====Net B.4 Dept Subnet 4
------------------------------------------------------------------------------
We want more than one backbone networks, with each backbone net connect couple
departments while each of these departments may have several subnets.
How should I setup the subnet addresses? Let's say we have a Class B address,
XX.YY., and we have two bytes (the third and the fourth octects) to play with.
------------------------------------------------------------------------------
Method 1:
Backbones - XX.YY.30, XX.YY.32, ..., XX.YY.38
Dept Nets - XX.YY.40, XX.YY.60, ..., XX.YY.240
Dept Subnets - XX.YY.41, XX.YY.42, ..., XX.YY.49 for dept net XX.YY.40
- XX.YY.61, XX.YY.62, ..., XX.YY.69 for dept net XX.YY.60
- ...
Is this setup a true subnetting? Our concerns are some software like Interleaf
using network license requires license server runs on, say, dept B net and
serves all subnets B.1, B.2, etc. At present, we have only backbone and dept
nets hook to it and each net has it own class B address. When Interleaf
license server runs on, say, dept A's net, nodes in other dept's net cannot
run Interleaf. Does anybody knows if the method 1 setting will work?
------------------------------------------------------------------------------
Method 2:
Let's play with the 3rd and 4th octects.
3rd octect 4th octect
+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+
| | | | | | | | | | | | | | | | | |
+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+
\ / \ / \ / \ /
backbone dept nets dept subnets nodes
Then we can have 4 backbones, each backbone can have 16 dept nets, each
dept net can have 8 subnets, and each subnets can have 126 (128 minus all 0s
and all 1s) nodes. By looking at books and references on Internet Addressing,
it seems to us that it should work and really follow the standard way for
subnetting. The subnet mask for every networks is FFFFFF80. Is it right?
Are we missing anything? Can some network gurus confirm that or give us
some insight as to how to do it the right way?
If we follow this scheme, what should be the addresses for nodes like routers,
brideges, workstations, and computers attached directly to backbone net,
or dept nets.
================================================================= Super Backbone | | | |
| | | ========+======== Backbone 1
| | ========+======================== Backbone 2
| ========+======================================== Backbone 3
==+==+==+==+==+==+==+==+==+==+==+==+==+==+==+==+================= Backbone 4
| | | | | | | | | | | | | | | |
| . . . . . . . . . . . . . . =+============ Dept net 1
| . . . . . . . . . . . . . . ...
| ...
=++==+===+===+===+===+===+===+============================== Dept net 16
| | | | | | | |
| . . . . . . ==+=================== Subnet 1
| . . . . . . ...
| ...
=+=============================================== Subnet 8
****************************************************************************
uunet!smosjc!lapyuntsuchiya@THUMPER.BELLCORE.COM (Paul Tsuchiya) (04/25/91)
In general, I think your methods are partitioning the address space up to much. Strictly speaking, all a address needs to have is net.subnet.host. There is no reason (as far as routing is concerned) to be able to look at a subnet number and say "that subnet is on backbone X, or in department Y". Of course, it might be convenient for a administrator to be able to do that, but that's only a convenience, not a necessity. The problem with putting too much into your addresses is that in overly constrains the number of addresses you can assign. For instance, with your method 1... > ------------------------------------------------------------------------------ > > Method 1: > > Backbones - XX.YY.30, XX.YY.32, ..., XX.YY.38 > Dept Nets - XX.YY.40, XX.YY.60, ..., XX.YY.240 > Dept Subnets - XX.YY.41, XX.YY.42, ..., XX.YY.49 for dept net XX.YY.40 > - XX.YY.61, XX.YY.62, ..., XX.YY.69 for dept net XX.YY.60 > - ... > > Is this setup a true subnetting? Our concerns are some software like Interleaf > using network license requires license server runs on, say, dept B net and > serves all subnets B.1, B.2, etc. At present, we have only backbone and dept > nets hook to it and each net has it own class B address. When Interleaf > license server runs on, say, dept A's net, nodes in other dept's net cannot > run Interleaf. Does anybody knows if the method 1 setting will work? > > ------------------------------------------------------------------------------ what happens when dept XX.YY.40 gets its 10th subnet? Then, you have to give that subnet a number from a different department, and you are worse off than if you didn't group them so nicely in the first place, because people will look at the new subnet number, and expect it to be in a department where it is not. (Routing, however, won't be confused because it doesn't care what department the subnet is in). As for licensed software like Interleaf, I don't know. I'm a bit surprised that they run their liscense such that they look at the network number of the thing asking for a liscense, and reject it if it is not network X. You'd think they would allow for defining multiple net numbers, or just part of a net number, for that matter. Also, you might look at RFC 1219. It discusses a method of assigning subnet numbers that maximizes use of the subnet number space. This way, for instance, you don't have to worry about how many hosts might be on a subnet, or how many subnets you might eventually have, etc. The technique, however, results in variable length masks, so you need a routing algorithm that handles variable length masks, like OSPF. I don't know what is available these days. What routers do you have between your subnets? PT Method 2: Let's play with the 3rd and 4th octects. 3rd octect 4th octect +---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+ | | | | | | | | | | | | | | | | | | +---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+ \ / \ / \ / \ / backbone dept nets dept subnets nodes Then we can have 4 backbones, each backbone can have 16 dept nets, each dept net can have 8 subnets, and each subnets can have 126 (128 minus all 0s and all 1s) nodes. By looking at books and references on Internet Addressing, it seems to us that it should work and really follow the standard way for subnetting. The subnet mask for every networks is FFFFFF80. Is it right? Are we missing anything? Can some network gurus confirm that or give us some insight as to how to do it the right way? If we follow this scheme, what should be the addresses for nodes like routers, brideges, workstations, and computers attached directly to backbone net, or dept nets. ================================================================= Super Backbone | | | | | | | ========+======== Backbone 1 | | ========+======================== Backbone 2 | ========+======================================== Backbone 3 ==+==+==+==+==+==+==+==+==+==+==+==+==+==+==+==+================= Backbone 4 | | | | | | | | | | | | | | | | | . . . . . . . . . . . . . . =+============ Dept net 1 | . . . . . . . . . . . . . . ... | ... =++==+===+===+===+===+===+===+============================== Dept net 16 | | | | | | | | | . . . . . . ==+=================== Subnet 1 | . . . . . . ... | ... =+=============================================== Subnet 8 **************************************************************************** uunet!smosjc!lapyun