Figure 14-1 Encryption And Decryption - Nortel Contivity 251 User Manual

14-2 Introduction to IPSec

Figure 14-1 Encryption and Decryption

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Data Confidentiality
The IPSec sender can encrypt packets before transmitting them across a network.
•
Data Integrity
The IPSec receiver can validate packets sent by the IPSec sender to ensure that the
data has not been altered during transmission.
•
Data Origin Authentication
The IPSec receiver can verify the source of IPSec packets. This service depends on
the data integrity service.
14.1.4 VPN Applications
The Contivity 251 supports the following VPN applications.
Linking Two or More Private Networks Together
Connect branch offices and business partners over the Internet with significant
cost savings and improved performance when compared to leased lines
between sites.
Accessing Network Resources When NAT Is Enabled
When NAT is enabled, remote users are not able to access hosts on the LAN
unless the host is designated a public LAN server for that specific protocol.
Since the VPN tunnel terminates inside the LAN, remote users will be able to
access all computers that use private IP addresses on the LAN.
Unsupported IP Applications
A VPN tunnel may be created to add support for unsupported emerging IP
applications.
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