Virtual Private Networks (VPNs)
VPN is one of the most used words in networking today and has many different meanings.
The broadest definition of a VPN is 'any network built upon a public network and partitioned for use by individual customers'. This results in public MPLS, frame relay, X.25, and ATM networks being considered as VPNs. These types of VPNs are generically referred to a Layer 2 VPNs.
However these days the term VPNs is usually used to refer to private networks constructed across shared IP backbones, referred to as 'IP VPNs'. In the many cases the shared IP backbone is some part of the public Internet.
There are fundamentally three different corporate or business uses of VPNs:
- Remote Access VPNs
- Intranet VPNs
- Extranet VPNs
Each kind of VPN has it own challenges, and different ways in which it can be built. The topologies of the different VPNs are also dramatically different. Access VPNs, are classical hub and spoke topologies with all the remotes connecting into one or two central sites. Intranet VPNs range from hub and spoke to being a full mesh. The Extranet VPN topology is least understood topology, and for one corporation appears to be hub and spoke, but when viewed for several corporations will be a partial to full mesh of links. These are all virtual topologies, not real topologies, so the underlying premise is that you have ubiquitous any to any communication between endpoints, and then impose the structure required.
IP VPNs are not simply encrypted tunnels, but encompass an entire spectrum of technologies:
- Security
- Firewalls
- Encryption
- Authentication / Authorization / Accounting
- Intrusion Detection - Active Audit
- Tunneling
- Quality of Service
- Network Management
Remote Access VPNs
Remote Access VPNs provide remote access to a corporate Intranet or extranet over a shared infrastructure with the same policies as a private network. Access VPNs enable users to access corporate resources whenever, wherever, and however they require. Access VPNs encompass analog, dial, ISDN, digital subscriber line (DSL), mobile IP, and cable technologies to securely connect mobile users, telecommuters, or branch offices.
Intranet VPNs
Intranet VPNs Link corporate headquarters, remote offices, and branch offices over a shared infrastructure using dedicated connections. Businesses enjoy the same policies as a private network, including security, quality of service (QoS), manageability, and reliability.
Extranet VPNs
Extranet VPNs link customers, suppliers, partners, or communities of interest to a corporate Intranet over a shared infrastructure using dedicated connections. Businesses enjoy the same policies as a private network, including security, QoS, manageability, and reliability.
Site-to-Site VPNs
Site-to-Site VPNs are an alternative WAN infrastructure that extends the classic WAN by replacing or augmenting existing private networks that utilise leased lines, Frame Relay, or ATM to connect remote and branch offices and central site(s). VPNS do not inherently change private WAN requirements, such as support for multiple protocols, high reliability, and extensive scalability, but instead meet these requirements more cost-effectively and with greater flexibility. Site-to-site VPNs can utilize the most pervasive transport technologies available today, such as the public Internet or service provide IP networks, by employing tunneling and encryption for data privacy and QoS for transport reliability.
Please call 0870 421 4023 to find out how VPNs can be utilised within your organisation, or e-mail sales@whitehelm.com requesting more information.
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