What Is L2Tp; What Is Ipsec; What Secure Protocols Does Ipsec Support; What Are The Differences Between 'Transport Mode' And 'Tunnel Mode - ZyXEL Communications P-661HW-D Series Support Note

P-661HW-D Series Support Notes
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
for security gateway to provide IPSec service for other machines lacking of
IPSec capability.
In this case, Transport mode only protects the upper-layer protocols of IP
payload (user data). Tunneling mode protects the entire IP payload including
user data.
31
All contents copyright © 2006 ZyXEL Communications Corporation.