ZyXEL Communications 2602HWNLI-D7A User Manual

 

All contents copyright (c) 2007 ZyXEL Communications Corporation.   

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With encryption, VPN guarantees the confidentiality of the original user data. 

 

Cost 

 

1). Cut long distance phone charges 

 

Because users typically dial the their local ISP for VPN, thus, long distance phone charge is reduced than 

making a long direct connection to the remote office.   

 

2).Reducing number of access lines   

 

Many companies pay monthly charges for two types access lines: (1) high-speed links for their Internet 

access and (2) frame relay, ISDN Primary Rate Interface or T1 lines to carry data. A VPN may allow a 

company to carry the data traffic over its   Internet access lines, thus reducing the need for some installed 

lines. 

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). 

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. 

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. 

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