Virtual Private Networks CCIE Security Bootcamp Training in Gurgaon India

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I’d be pretty willing to bet you’ve heard the term VPN more than once. Maybe you even know
what one is, but just in case, a virtual private network (VPN) allows the creation of private networks
across the Internet, enabling privacy and tunneling of non-TCP/IP protocols.
VPNs are used daily to give remote users and disjointed networks connectivity over a public
medium like the Internet instead of using more expensive permanent means. For example, instead
of shelling out for a point-to-point connection between two sites (which is pretty secure in itself),
you can use a less-expensive Internet connection to each site and then run a VPN tunnel between
the sites.
Summary 495
There are three different categories of VPNs, based upon the role they play in a business:
Remote access VPNs Remote access VPNs allow remote users like telecommuters to
securely access the corporate network wherever and whenever they need to.
Site-to-site VPNs Site-to-site VPNs, or intranet VPNs, allow a company to connect its
remote sites to the corporate backbone securely over a public medium like the Internet instead
of requiring more expensive WAN connections like MPLS or Frame Relay.
Extranet VPNs Extranet VPNs allow an organization’s suppliers, partners, and customers
to be connected to the corporate network in a limited way for Business-to-Business (B2B)
communications.
There’s more than one way to bring a VPN into being. The first approach uses IPSec to create
authentication and encryption services between endpoints on an IP network. The second way
is done via tunneling protocols, allowing you to establish a tunnel between endpoints on a
network. The tunnel itself is a means for data or protocols to be encapsulated inside another
protocol—clean!
I really need to describe four of the most common tunneling protocols in use:
Layer 2 Forwarding (L2F) Layer 2 Forwarding (L2F) is a Cisco proprietary tunneling protocol
and their initial tunneling protocol created for virtual private dial-up networks (VPDNs). A VPDN
allows a device to use a dial-up connection to create a secure connection to a corporate network.
L2F was later replaced by L2TP, which is backward compatible with L2F.
Point-to-Point Tunneling Protocol (PPTP) Point-to-Point Tunneling Protocol (PPTP) was
created by Microsoft to allow the secure transfer of data from remote networks to the corporate
network.
Layer 2 Tunneling Protocol (L2TP) Layer 2 Tunneling Protocol (L2TP) was created by
Cisco and Microsoft to replace L2F and PPTP. L2TP merged the capabilities of both L2F and
PPTP into one tunneling protocol.
Generic Routing Encapsulation (GRE) Generic Routing Encapsulation (GRE) is another
Cisco proprietary tunneling protocol. It forms virtual point-to-point links, allowing for a variety
of protocols to be encapsulated in IP tunnels.