public vs private data network

Private vs Public refers to the IP addressing scheme. You can use either globally routed IP's (public) or private IP's 10.0.0.0 - 10.255.255.255 (10/8 prefix) 172.16.0.0 - 172.31.255.255 (172.16/12 prefix) 192.168.0.0 - 192.168.255.255 (192.168/16 prefix). See RFC 1918 for more details.

I might have been misinterpreted in my question. I was asking public and private data networks in terms of wide area implementation of connecting geographically separated locations using telcos and not in terms of ip addressing scheme.

In article , jonnah wrote: :what is the difference between public and a private data network? am I :correct in assuming that if you use a *public* data network to connect :your remote offices with your branch offices, you either use the :Internet as the Public DN or frame relay (as the Public DN of a telco) :but if you use leased lines or pt to pt links, then is it considered :as a *private* data network? (since you're not sharing the links with :others) if anybody knows, please enlighten me

Pretty much. If a random person around the world can get packets to your security gate then you are on a public data network. If only a closed list of places can get to your security gate, and you can't get out either then you are on a private data network.

In between would be semi-private networks that have clouds of accessible devices and security gateways to public networks. For example, a research network might allow public email in and might allow insiders a wide variety of outward accesses, but the basic security controls might be far away from most of the member systems.

To really be considered a private network in the traditional PSTN sense, there can't be -any- cross-border traffic possible through the network facilities.

No, your question was clear, and your own explanation was close on -- Walter's (elsewhere) this thread might have amplified on it a bit, but notice that as he introduced "semi-private" (or was it "semi-public" ) that these concept are somewhat dependent on context and point of view.

So is it safe to say that if I use leased lines to connect my sites it's on a private network, if I use the frame relay network of a telco to connect the sites its a semi-private network and if I use the internet (via ip vpn) to connect my sites its on a public network....?

thanks

In article , jonnah wrote: :So is it safe to say that if I use leased lines to connect my sites :it's on a private network, if I use the frame relay network of a telco :to connect the sites its a semi-private network and if I use the :internet (via ip vpn) to connect my sites its on a public network....?

I have never been involved with a FR installation, but my understanding is that FR can be configured as either public or private. That is, if you can find a carrier to serve all of your sites, that they can configure the FR for private access (e.g., using VLANs or MLPS), but that FR could also be configured to an ISP's gateway to the internet (which would make it public.)

Semi-private (or semi-public) is not a generally accepted term: I used it for lack of anything better. I just didn't want to be "black and white" about it when there is clearly opportunity for hybrids. Suppose for example that you used a FR cloud to link your sites, and you installed a firewall that allowed in public only access to your web servers, with the firewall transparently redirecting into the appropriate location within the cloud. As far as the things other than the web servers are concerned, the cloud would be "private" because no public packets can get there and they can't get out -- but the web servers would be public... and possibly thousands of miles from the firewall, reached through the FR cloud.

Jonnah,

As an earlier post said, it's context sensitive. The Internet, PSTN (& often wireless) are public. LAN with all wires inside your buiding where you can see them is private. Anything else depends on context, sensitivity of data being carried, who you're talking to, etc; and could be one or the other (semi- is not used).

Many consider leased lines private. But they can terminate in outside cabinets with generic keys; they're patched in exchanges by telco techs that can make mistakes, or be partial to bribes. Though maybe your data isn't precious enough to worry.

If your interest is data confidentiality (e.g. any volume of financial transactions or personal data) you'll assume that any cable (incl. all leased lines & fibre) that you can't see, someone else can, and encrypt what's on it.

HTH, Ian