a VPN question

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Dec 29th, 2008
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I asked a question just a minute ago about how GRE is encapsulated. That might help with this one, but does using a GRE tunnel mean that you are using a VPN? I would think maybe yes and maybe no, and if not, it's because you have to use IPSec to be using a VPN. I would think so because it says there are 2 ways to use VPNs...through tunneling and through IPSec. This subject is very confusing for me. Thank you,


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rais Tue, 12/30/2008 - 07:41
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GRE is a tunneling protocol and tunneling is one of the main features of a VPN. Note that VPN is usually encrypted but GRE is inherently non-encrypted. GRE can carry protocols other than IP as well.

IPSec is not a must for VPN but is a usual choice for remote access VPN. Note that L3VPNs don't use IPSec but they still use tunnels and are called VPN.

Hope this helps.

Richard Burts Tue, 12/30/2008 - 20:52
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You ask the question:"does using a GRE tunnel mean that you are using a VPN?". And the answer is not necessarily.

In current usage GRE is frequently associated with VPN. But there are certainly implementations of GRE that are not associated with VPN (just as there are implementations of VPN that are not associated with GRE).



Istvan_Rabai Thu, 01/01/2009 - 01:22
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Hi J.D.,

The definition of VPN is: using a shared infrastructure to implement private networks.

The degree of security is not present in the definition.

To implement a VPN, you can use GRE or IPSEc or some other technologies. IPSec in itself can also be thought of as a kind of tunneling.

As Rick and Rais say, these technologies can be put together to enhance the features of a VPN.




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