Cisco ISA550 Administration Manual page 128

Networking
Configuring the WAN
Network Addressing
Mode
L2TP
Cisco ISA500 Series Integrated Security Appliances Administration Guide
Configuration
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 configuration:
• IP Address: Enter the IP address of the WAN port that can be accessible
from the Internet.
• Subnet Mask: Enter the subnet mask.
• Gateway: Enter the IP address of default gateway.
• User Name: Enter the username that is required to log into the L2TP
server.
• Password: Enter the password that is 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 alive: 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.
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