ZyXEL Communications P-202 - Manual (Page 28)

P-202H Plus v2 Support Notes
3. What are most common VPN protocols?
There are currently three major tunneling protocols for VPNs. They are Point-to-
Point Tunneling Protocol (PPTP), Layer 2 Tunneling Protocol (L2TP) and Internet
Protocol Security (IPSec).
4. What is PPTP?
PPTP is a tunneling protocol defined by the PPTP forum that allows PPP packets
to be encapsulated within Internet Protocol (IP) packets and forwarded over any
IP network, including the Internet itself. The PPTP is supported in Windows NT
and Windows 98 already. For Windows 95, it needs to be upgraded by the Dial-
Up Networking 1.2 upgrade.
5. What is L2TP?
Layer Two Tunneling Protocol (L2TP) is an extension of the Point-to-Point
Tunneling Protocol (PPTP) used by an Internet service provider (ISP) to enable
the operation of a virtual private network (VPN) over the Internet.
6. What is IPSec?
IPSec is a set of IP extensions developed by IETF (Internet Engineering Task
Force) to provide security services compatible with the existing IP standard
(IPv.4) and also the upcoming one (IPv.6). In addition, IPSec can protect any
protocol that runs on top of IP, for instance TCP, UDP, and ICMP. The IPSec
provides cryptographic security services. These services allow for authentication,
integrity, access control, and confidentiality. IPSec allows for the information
exchanged between remote sites to be encrypted and verified. You can create
encrypted tunnels (VPNs), or just do encryption between computers. Since you
have so many options, IPSec is truly the most extensible and complete network
security solution.
7. What secure protocols does IPSec support?
There are two protocols provided by IPSec, they are AH (Authentication Header,
protocol number 51) and ESP (Encapsulated Security Payload, protocol number
50).
8. What are the differences between 'Transport mode' and 'Tunnel mode?
The IPSec protocols (AH and ESP) can be used to protect either an entire IP
payload or only the upper-layer protocols of an IP payload. Transport mode is
mainly for an IP host to protect the data generated locally, while tunnel mode is
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