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Reference Manual for the Model FVS318 Cable/DSL ProSafe VPN Firewall
Advanced Configuration 8-9
Any packets sent through the firewall that are larger than the configured MTU size will be
repackaged into smaller packets to meet the MTU requirement. To change the MTU size:
1. Under MTU Size, select Custom.
2. Enter a new size between 64 and 1500.
3. Click Apply to save the new configuration.
By default, the firewall will function as a DHCP (Dynamic Host Configuration Protocol) server,
allowing it to assign IP, DNS server, and default gateway addresses to all computers connected to
the router's LAN. The assigned default gateway address is the LAN address of the firewall. IP
addresses will be assigned to the attached PCs from a pool of addresses specified in this menu.
Each pool address is tested before it is assigned to avoid duplicate addresses on the LAN.
For most applications, the default DHCP and TCP/IP settings of the firewall are satisfactory. See
“IP Configuration by DHCP”onpage B-10 for an explanation of DHCP and information about
how to assign IP addresses for your network.
Use router as DHCP server
If another device on your network will be the DHCP server, or if you will manually configure the
network settings of all of your computers, clear the ‘Use router as DHCP server’ check box.
Otherwise, leave it checked.
Specify the pool of IP addresses to be assigned by setting the Starting IP Address and Ending IP
Address. These addresses should be part of the same IP address subnet as the firewall’s LAN IP
address. Using the default addressing scheme, you should define a range between 192.168.0.2 and
192.168.0.253, although you may wish to save part of the range for devices with fixed addresses.
The firewall will deliver the following parameters to any LAN device that requests DHCP:
• An IP Address from the range you have defined
• Subnet Mask
• Gateway IP Address (the firewall’s LAN IP address)
• Primary DNS Server (if you entered a Primary DNS address in the Basic Settings menu;
otherwise, the firewall’s LAN IP address)
• Secondary DNS Server (if you entered a Secondary DNS address in the Basic Settings menu