User's Manual

Networking
Configuring the WAN
Cisco ISA500 Series Integrated Security Appliance Administrator Guide 110
4
L2TP Choose this option if you want to use IPSec to connect a L2TP
(Layer 2 Tunneling Protocol) server and encrypt all data
transmitted from the client to the server. However, it does not
encrypt network traffic to other destinations. Use the necessary
information from your ISP to complete the L2TP configurations:
• IP Address: Enter the IP address of the WAN port that
can be accessable from the Internet.
• Netmask: Enter the IP address of the subnet mask.
• Gateway: Enter the IP address of default gateway.
• User Name/Password: Enter the user name and
password that are required to log into the L2TP server.
• L2TP Server IP Address: Enter the IP address of the
L2TP server.
• Secret (Optional): L2TP incorporates a simple, optional,
CHAP-like tunnel authentication system during control
connection establishment. Enter the secret for tunnel
authentication if necessary.
• Connect Idle Time: Choose this option to let the security
appliance disconnect from the Internet after a specified
period of inactivity (Idle Time). This choice is
recommended if your ISP fees are based on the time that
you spend online.
• Keep Live: Choose this option to keep the connection
always on, regardless of the level of activity. This choice
is recommended if you pay a flat fee for your Internet
service.
• MTU: Choose Auto to use the default MTU size, or
choose Manual if you want to specify another size.
• MTU Value: If you choose Manual, enter the custom MTU
size in bytes.
NOTE Unless a change is required by your ISP, it is recommended
that the MTU values be left as is.
Network
Addressing
Mode
Configurations