Netgate SG-1000 Product Manual page 11

Product Manual, SG-1000
DHCP is the most common type of interface for home cable modems. One dynamic IP address is issued from the
ISP DHCP server and will become the public IP address of the network behind this firewall. This address will change
periodically at the discretion of the ISP. Select DHCP as shown and proceed to the next section.
1.2.12 MAC Address
If replacing an existing firewall, the WAN MAC address of the old firewall may be entered here, if it can be determined.
This can help avoid issues involved in switching out firewalls, such as ARP caches, ISPs locking to single MAC
addresses, etc.
If the MAC address of the old firewall cannot be located, the impact is most likely insignificant. Power cycle the ISP
router and modem and the new MAC address will usually be able to get online. For some ISPs, it may be necessary to
call them when switching devices, or an activation process may be required.
1.2.13 Configuring MTU and MSS
MTU or Maximum Transmission Unit determines the largest protocol data unit that can be passed onwards. A 1500-
byte packet is the largest packet size allowed by Ethernet at the network layer and for the most part, the Internet so
leaving this field blank allows the system to default to 1500-byte packets. PPPoE is slightly smaller at 1492-bytes.
Leave this blank for a basic configuration.
1.2.14 Configuring DHCP Hostname
Some ISPs specifically require a DHCP Hostname entry. Unless the ISP requires the setting, leave it blank.
1.2. Getting Started 9