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Soda Ant
n00b
Joined: 14 Sep 2005
Posts: 12
Location: Milky Way
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 Posted: Wed Oct 05, 2005 8:34 pm Post subject: Why 192.168.x.x ?? |
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| Why do most people use 192.168.x.x when they need an RFC 1918-style address? Why not use the class A equivalent, 10.x.x.x? It seems to me that this would save a lot of typing. |
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thoughtform
l33t
Joined: 24 May 2004
Posts: 600
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| Posted: Wed Oct 05, 2005 8:52 pm Post subject: |
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hmm.
well in my case, my router was 192.168.1.1 when i got it so
laziness i guess.
heh |
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jasperbg
n00b
Joined: 02 Mar 2005
Posts: 62
Location: Christchurch, New Zealand
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| Posted: Wed Oct 05, 2005 8:57 pm Post subject: |
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Because most people's networks don't need about 16 million nodes. I did read somewhere that routing can be slowed down somewhat on a class A network because of the larger address space; not sure how true that is though, nor how much of a slowdown you could expect.
I always use an address space suitable for the size of the network and its expected growth. |
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think4urs11
Bodhisattva
Joined: 25 Jun 2003
Posts: 6659
Location: above the cloud
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| Posted: Wed Oct 05, 2005 9:15 pm Post subject: |
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wheres the problem with subnetting the 10.x.y.z down to /24 or even smaller to suit your needs? I've 10.x.y.96/27 here.
The main reason imho is the simple fact that a lot of cheap routers have a factory default of 192.168.x.y and John/Jane Doe don't care about which network to use. At the end it doesn't matter at all - how often do you type these addresses? (tip: put them in /etc/hosts as pc1/2/3)
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Nothing is secure / Security is always a trade-off with usability / Do not assume anything / Trust no-one, nothing / Paranoia is your friend / Think for yourself |
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DaveArb
Guru
Joined: 29 Apr 2004
Posts: 510
Location: Texas, USA
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| Posted: Wed Oct 05, 2005 9:20 pm Post subject: |
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| jasperbg wrote: | | I did read somewhere that routing can be slowed down somewhat on a class A network because of the larger address space |
I think you'd be running on some pretty old gear if it's still using classes, everything's gone CIDR now.
Along with Think4UrS11's answer about cheap routers, there is probably also a legacy hangover from old guys like me who grew up with classes, using old-style class A space still feels kind of funny. 
Dave |
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kashani
Advocate
Joined: 02 Sep 2002
Posts: 2032
Location: San Francisco
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| Posted: Wed Oct 05, 2005 9:39 pm Post subject: |
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| jasperbg wrote: | Because most people's networks don't need about 16 million nodes. I did read somewhere that routing can be slowed down somewhat on a class A network because of the larger address space; not sure how true that is though, nor how much of a slowdown you could expect.
I always use an address space suitable for the size of the network and its expected growth. |
I suspect that the slow down was mentioned in the context of increased broadcast traffic with a flat network and lots of nodes. Broadcast storms are another possiblity in a flat network that large, but most of today's switches are pretty smart and you'd really need 500+ devices on the network to cause real degradation and probably have very chatty apps on top of it.
From the math side of things bit matching 32bit IPs and netmasks takes the same resources regardless of the data represented by the bits. I suppose if your gear was using classful routing you could skip the bit math and use a cheesy algorithm which probably did save you some CPU in '95. Since everything support CIDR these days that option isn't a possibility anymore.
kashani
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tgh
Apprentice
Joined: 05 Oct 2005
Posts: 222
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| Posted: Thu Oct 06, 2005 12:56 am Post subject: |
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Have to agree with the above posters... John/Jane Doe use 192.168.0.0/24 and 192.168.1.0/24 because that's what comes pre-configured on most home routers. I personally always make sure that user's home networks are set to use anything but "0" or "1" in the 3rd octet. So I might set them to use 192.168.102.0/24 (or some other random 3rd octet).
And there's also the option of the 172.16.0.0 to 172.31.255.255 address range. Which is good for setting up networks that need to be larger then 254 hosts but where you only have a few locations and at most a few thousand machines. Also, hardly anyone uses that address range (large companies typically use 10.x.x.x and small companies end up in the 192.168.x.x range). |
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