Which class of network do I use?

ajoeiam

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Greetings

There are 3 classes of ipv4 private networks available.

Don't think the ISP I am in transition to is looking at ipv6 any time in the near future - - - likely at least 1 year or more out (likely more - - -grin!).

Looking longer term for my lan here - - - - I don't think I 'need' a class A network and I'm not sure a class C gives that much room if one is looking at setting up lots of sensors, sub-systems and systems with lots of controlled functions.
Is there any kind of guidelines that help decide at what kind of lan it might be better to setup as a Class B rather than as a class C right off the hop?

Ideas/suggestions/thoughts sought - - - - please?

TIA
 


You don't have to go full blown class A or class B.
You can "supernet" multiple class C subnets.

If you don't need 64,000 addresses in 16,000 subnet ( class B ) just use say 10 or 12 class C's.

subnet mask of 255.255.224.0 would give you 30 class C subnets. ( Over 7000 IP addresses )
 
what in the world are you hooking up at home that needs so many addresses. You can daisy chain routers and have literally thousands of IP addresses available. I can't imagine any reason you would need class A or B at home. I have businesses with dozens of nodes on the network and never had issues. Not sure where you are getting information but you may want to stop listening to that source and just "Keep It Simple". besides you need Cisco or Juniper routers to do those A and B networks. I don't think you want to spend several hundred dollars on a single router.
 
OK - - - - I'm likely misunderstanding networking - - - - which is why I'm here - - - - trying to learn stuff that I can't find when looking for stuff.

AIUI on 192.168.xxx.xxx I really only have access to up to 255 discrete connections.

I can add another router but then I only have access to 510 connections.

If I'm using 172.16.0.0 to 172.31.255.255 do I have access to 64516 connections at any one time (from one router)?

(Perhaps posing the question in this way will make things clearer.)
 
you will not get that from an off the shelf router. Your first assessment of 255 connections was correct, but I have to renew my question, Are you going to have more than 255 connections? if so you may want to spend money on a professional cisco router but then you have to learn how to program it. they do not come out of the box ready to use. In fact out of the box they are paper weights. You have to program them from scratch which mean you need training or a professional.

If you are looking for 500 connections you can do it yourself with 2 off the shelf routers. But what are you doing that would use that much? I have a business and 2 buildings on the same lot sharing internet and cameras plus wifi enabled power controllers and still have not exceeded 50 connections. I ask why you want 64,000 plus connections because if you really don't need it, it makes a world of difference. Also the way the routers are connected will make a difference also so if you can be specific about why so many connections and just how many you need, I can help much better.
 
My question is switches, you can buy 32 and 48 ports switches relatively cheap.
( Less than $300.00) However a managed catalyst switch can cost about 20k
for 48 ports. A catalyst 9000 series only supports up to 384 ports. Yes, you can daisy chain
switches up to a point.

It sounds like you think you want a flat network, but you probably really don't.
I mean, you could have a netmask of 0.0.0.0 and broadcast to the whole world.
Roughly 4 billion addresses if I remember. If you have 4 billions computer broadcasting
every packet to 4 billion other computers thousand of times a second... well that's called
a broadcast storm. The whole reason for subnets, is so that you only broadcast to your
local subnet. Class C ( 250 hosts ) have become the de facto standard for this reason.
Good luck buying a flat switch that has 4 billion ports. I would hate to see the cost.

Hence routers. The router of a router is to ... ummm. "route" ( no pun intended) traffic
between two subnets. If you only had 2 class C's, it's not that big of deal, but once you
start having hundreds and thousands of devices, you have to worry about broadcast storms.
You don't want to saturate your network with useless packets you don't care about.

So a router only send traffic from a specific subnet to a specific subnet.... all other subnets
don't get any unwanted traffic.

In my opinion, it's better to go ahead and have multiple subnets and route between them,
than to have one huge flat network with thousands of addresses competing for bandwidth.
 
I have been reluctant to get involved in this thread because I have not tried some of the configurations that seem obvious to me. When I create local LANs, I have always created them with /24 (255.255.255.0) subnet masks, and it covers a lot of LANs in homes, engineering labs, and elsewhere.

I do not understand why @ajoeiam cannot run their local LAN with a /23 or even a /16 network mask. The local address space would be larger, but the switches and router should be able to handle it. I have not posted in this thread because I never tried it myself. As I wrote, I always used a /24 for my LAN networks.

I would arrange the network to avoid overlap issues with the common 192.168-net and 10-net ranges that are popular with appliances and VPNs, addresses like 192.168.0.x, 192.168.1.x, 192.168.100.x, and also 10.0.0.x and 10.0.1.x, for example.

There will be limitations - table sizes, how much traffic the network can carry, and ultimately the number of available ports on a public IP address.

Using a netmask with a larger address space should be good as long as the router can handle the device and traffic load. I have been reluctant to say that because I have not tried it myself and I am too lazy to set up a testbed this morning.
 
I do not understand why @ajoeiam cannot run their local LAN with a /23 or even a /16 network mask. The local address space would be larger, but the switches and router should be able to handle it. I have not posted in this thread because I never tried it myself. As I wrote, I always used a /24 for my LAN networks.

This is basically what I recommended in post #2. I run a /23 at my house. We have gone as big as a /20 where I work.
I personally don't think I would go with a /16 on a flat network, but to each his own.

One thing we have noticed, is that server network "busy-ness" makes a big difference.
If you have a database server that only gets a few hundred or few thousand transactions a day, that's fine.
If you have 10 or 12 web servers that are constantly busy with hundreds of users logged in all the time, you might not
want to put them on the same subnet.

Ray
CCNA/ENCOR/CISE
CSCO311240558

RHCSA9
 
Also if you're going to really have an enterprise network, are you going to have redundant NICs.
or NIC teaming/bonding? Are you going to have redundant paths with spanning tree set up?
Security, firewalls, net-appliances, Application layer routers?

..and new that you've spent all these thousands of dollars to do this... are you going to go geographically diverse?
If you do this with private ( non internet routable ) IPs, you'll need to encapsulate the packets a VPN or private
external network.

...and realistically, where are you going to store switches for say 4,000 devices ( that just 16 class C's )
That will take up half a room easily, then there's your electric bill, air conditioning considerations, it gets
expensive in a hurry.

For example one of our data centers, has about 6,000 physical servers, with about 24 switches, and
8 multiport routers. I don't even know how many firewalls and net appliances we have.
One of our purchasing agents told me we over $18million (US) in assets just in this one data center.

But I suppose that's including NAS and fiber switches also. Still....
Just the cost of 4,000 ethernet cables alone....
 
you will not get that from an off the shelf router. Your first assessment of 255 connections was correct, but I have to renew my question, Are you going to have more than 255 connections? if so you may want to spend money on a professional cisco router but then you have to learn how to program it. they do not come out of the box ready to use. In fact out of the box they are paper weights. You have to program them from scratch which mean you need training or a professional.

If you are looking for 500 connections you can do it yourself with 2 off the shelf routers. But what are you doing that would use that much? I have a business and 2 buildings on the same lot sharing internet and cameras plus wifi enabled power controllers and still have not exceeded 50 connections. I ask why you want 64,000 plus connections because if you really don't need it, it makes a world of difference. Also the way the routers are connected will make a difference also so if you can be specific about why so many connections and just how many you need, I can help much better.
Hmmmmmm - - - - why would I 'want' to run 2 routers?

I'm a thinking that my original email was largely glossed over.

This an subsequent responses read like the only place multiple ips get used in is in an office.
Guess no one has ever run into manufacturing - - - - you know where you might have 5 sensors reading things on one single stream (at different point obviously).
 
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My question is switches, you can buy 32 and 48 ports switches relatively cheap.
( Less than $300.00) However a managed catalyst switch can cost about 20k
for 48 ports. A catalyst 9000 series only supports up to 384 ports. Yes, you can daisy chain
switches up to a point.

It sounds like you think you want a flat network, but you probably really don't.
I mean, you could have a netmask of 0.0.0.0 and broadcast to the whole world.
Roughly 4 billion addresses if I remember. If you have 4 billions computer broadcasting
every packet to 4 billion other computers thousand of times a second... well that's called
a broadcast storm. The whole reason for subnets, is so that you only broadcast to your
local subnet. Class C ( 250 hosts ) have become the de facto standard for this reason.
Good luck buying a flat switch that has 4 billion ports. I would hate to see the cost.

Hence routers. The router of a router is to ... ummm. "route" ( no pun intended) traffic
between two subnets. If you only had 2 class C's, it's not that big of deal, but once you
start having hundreds and thousands of devices, you have to worry about broadcast storms.
You don't want to saturate your network with useless packets you don't care about.

So a router only send traffic from a specific subnet to a specific subnet.... all other subnets
don't get any unwanted traffic.

In my opinion, it's better to go ahead and have multiple subnets and route between them,
than to have one huge flat network with thousands of addresses competing for bandwidth.

Except - - - I'm not broadcasting.

Looking at things from exactly the opposite direction. Looking to have a plethora
of sensors, micro-controllers and even SoCs and they each need to be - - - or are
going to be connected.

Just think - - - - if there are 4 connections per space and my initial iteration is for
12 spaces - - - then next level for me (depends upon a lot of factors) is going to be
somewhere between 50 and 180 spaces - - - - - each with those 4 and maybe even
more connections - - - - so 180 x 4 is - - - oops its bigger than 255 - - - right??!!??

So if I want individual connections - - - - well - - - given previous suggestions - - -
I could put a router at each space - - - - then I would have from 50 to 180 routers
to manage - - - - that seems rather awkward - - - yes? Would it be easier to manage
a space that does have access to more than 254 access points?
 
Also if you're going to really have an enterprise network, are you going to have redundant NICs.
or NIC teaming/bonding? Are you going to have redundant paths with spanning tree set up?
Security, firewalls, net-appliances, Application layer routers?

..and new that you've spent all these thousands of dollars to do this... are you going to go geographically diverse?
If you do this with private ( non internet routable ) IPs, you'll need to encapsulate the packets a VPN or private
external network.

...and realistically, where are you going to store switches for say 4,000 devices ( that just 16 class C's )
That will take up half a room easily, then there's your electric bill, air conditioning considerations, it gets
expensive in a hurry.

For example one of our data centers, has about 6,000 physical servers, with about 24 switches, and
8 multiport routers. I don't even know how many firewalls and net appliances we have.
One of our purchasing agents told me we over $18million (US) in assets just in this one data center.

But I suppose that's including NAS and fiber switches also. Still....
Just the cost of 4,000 ethernet cables alone....

Sorta comparable technology today is costing some $50 to 60k per space.

Don't think mine is going to be any simpler - - - - maybe even more complex as what I'm
referring to is 20 to 35 years old so its quite outdated technology thinking - - - just marketed
by a couple 800# gorilla type firms and they're making buckets of $$$$$$ - - - - why would
they want to change.

So its not a simple project - - - - is that precluded somehow?

Expensive - - - - I wasn't expecting cheap - - - - and you're only thinking office technology - - -
you want some more sticker shock - - - - look into industrial - - - office stuff is cheap in
comparison.

Thanks for the ideas guys - - -

Arrivederci
 
without seeing the topology and geography of what you need it would be a total waste to put a router in for each space handling 12 items. You are better to divide up the various nodes you will be needing and flat out math says this... 180x4=720 each router handling 200 to keep things safe as you never want to run anything at it's limit. You would need 4 routers that you can connect and manage easily.
router 1 192.168.0.x
router 2 192.168.1.x
router 3 192.168.2.x
router 4 192.168.3.x

Other option is professional cisco router and set up 4 different vlans on it and learn to program cisco ios.

I hope these are not wireless connections otherwise you will need to completely rethink everything.
 

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