Local Network IPs - 10.0.0.0/8 or 192.168.0.0/16?

mike9010 asks: "After reading a few articles on the net about networking, I have come up with a question. It seems that most of them say to use 192.168.0.0/16 for a local network. Why not use 10.0.0.0/8 though? It is my understanding that it can hold a lot more IP addresses, and it is also prettier." What local network range are you using for your networks?

Comments

10.0.0.0/8

[MazTaim]

I actually asked this question once. Nobody could really give me a good answer. I personally prefer 10.0.0.0 over 192.168.0.0. It does look pretier, it's easier to type, and you do have more IPs to play with. Who has need for all those IPs is beyond me, but I say you can never have too many IPs.

It does look prettier. here is how I broke down my NAT network

10.0.0.0-255 = Routers/Server - Kinda, sorta DMZ
10.0.1.0-255 = Wired Workstations
10.0.2.0-255 = Wireless Workstations
10.0.3.0-255 = Test stuffage

192.168.0.0 is the defacto standard for just about any router you buy off the shelf. Perhaps there is a valid reason?

Re:What if your provider has a private network too

[ArmorFiend]

furthermore, DO NOT use 192.168.0.XX. Because you might get a job with a vpn-ing company that uses that to. Get a random number under 256, and use that instead of 1.

e.g. I use 192.168.88.XX. I used to use 192.168.1.XX, but guess what, I got a job ...

IP Subnetworking

[hawkstone]

From the IP subnetworking HOWTO:

There are also special addresses that are reserved for 'unconnected' networks - that is networks that use IP but are not connected to the Internet, These addresses are:-

* One A Class Network
10.0.0.0
* 16 B Class Networks
172.16.0.0 - 172.31.0.0
* 256 C Class Networks 192.168.0.0 - 192.168.255.0

The one most often used by home networking products is 192.168.1.x in my experience, not the full /16. They are designed to hold 254 addresses, no more. Why are these designed for only a small number of IP addresses? Well, the home routers often have 4 ports, with maybe wireless. Are you really going to have a few hundred clients? Anyway, it's probably best to stick with the 192.168.1.x for a small network if you're planning on connecting to one of these. If, not, do whatever floats your boat!

Choose randomly

[Fluffy the Cat]

RFC 1918 recommends that you choose a network randomly in order to reduce the chances of colliding with any other internal network you may ever want to connect to.

Pedantic correction:

[Asprin]

192.168.0.0/16 doesn't exist.

It's really a set of 256 (254, really because you aren't supposed to use 0 or 255) /24 networks:
192.168.1.0/24
192.168.2.0/24
192.168.3.0/24
...
192.168.254.0/24

Now, if you set up your internal routing and gateways correctly, the difference doesn't matter, but TECHNICALLY, since 192 starts with the binary digits '110', it's a class C (/24) network.

FYI.

Which (10.0.0.0/8 or 192.168.0.0/24) you use doesn't matter unless you need to connect your network to somebody else's, but a bad decision (or evaluation of capacity) early on can come back to create problems if your network grows beyond the address space you planned for it. GOOD DESIGN IS ESSENTIAL to preventing problems down the road. Usually the # of hosts you need on your network segments drives the decision. Some larger networks will use the /24 blocks for local departmental LANs, and hook them together with /8 block addresses on the internetwork routers, but there are gobs of ways to do it.

I'd recommend searching Cisco's site for white papers on network design, or maybe googling for TCP/IP tutorials.

Re:Hi, I'm ignorant. Pleeztameecha!

[Medieval_Gnome]

It is a method of indicating how many bits in the address are part of the 'network' number, as opposed to the 'host' number. For example..

In 10.0.0.0/8 that means there are 8 bits that identify the network (10.x.x.x) and 24 bits (IP addresses are 32 bits, 8 bits are already used for network; 32-8=24) for the machine number (the x.15.53.45)

So now, for '192.168.0.0/16'. The 192.168 part is the network part, and the '/16' means the last 16 bits are used for hosts. When the slash-number is larger, that means the person with that IP range has less IPs. /24 means the user has 254 hosts at their disposal, while a /8 means over 16 million.

I really hope this helps, sorry I'm not the greatest at explaining things.

CIDR!

[tachyonflow]

Welcome to the world of classless routing!

192.168.0.0/16 certainly does exist. The first three bits has not dictated the netmask for years. See RFC1817 for more information on this. Here's a relevant excerpt (emphasis added):

Classless Inter-Domain Routing (CIDR) ([RFC1518], [RFC1519]) is deployed in the Internet as the primary mechanism to improve scaling property of the Internet routing system. Essential to CIDR is the generalization of the concept of variable length subnet masks (VLSM) and the elimination of classes of network numbers (A, B, and C). The interior (intra-domain) routing protocols that support CIDR are OSPF, RIP II, Integrated IS-IS, and E-IGRP. The exterior (inter-domain) routing protocol that supports CIDR is BGP-4. Protocols like RIP, BGP-3, EGP, and IGRP do not support CIDR.

Re:FP...

[afidel]

These are not BS. This was an IP block set aside for future use and Apple, MS, Sun, and others decided to use it for local link zero config stuff. This was codified by the ietf and is specified in RFC 3330 and other places.