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N900 Wireless Dual Band Gigabit Router R4500

•

Default DMZ Server

. This feature is sometimes helpful when you are playing online

games or videoconferencing. Be careful when using this feature because it makes the

firewall security less effective. For more information, see the following section,

Default

DMZ Server

.

•

Respond to Ping on Internet Port

. If you want the router to respond to a ping from

the Internet, select this check box. Use this only as a diagnostic tool because it allows

your router to be discovered. Do not select this check box unless you have a specific

reason.

•

Disable IGMP Proxying

. IGMP proxying allows a computer on the local area network

(LAN) to receive the multicast traffic it is interested in from the Internet. You can select

this check box to disable the feature if you do not need it.

•

MTU Size (in bytes)

. The normal MTU (maximum transmit unit) value for most

Ethernet networks is 1500 bytes, or 1492 bytes for PPPoE connections. For some

ISPs, you might need to reduce the MTU. This is rarely required, and should not be

done unless you are sure that it is necessary for your ISP connection. See

Change

the MTU Size

on page 37.

•

NAT Filtering

. Network Address Translation (NAT) determines how the router

processes inbound traffic. Secured NAT provides a secured firewall to protect the

computers on the LAN from attacks from the Internet, but might prevent some Internet

games, point-to-point applications, or multimedia applications from functioning. Open

NAT provides a much less secured firewall, but allows almost all Internet applications

to function.

Default DMZ Server

The default DMZ server feature is helpful when you are using some online games and

videoconferencing applications that are incompatible with Network Address Translation

(NAT). The router is programmed to recognize some of these applications and to work

correctly with them, but other applications might not function well. In some cases, one local

computer can run the application correctly if that computer’s IP address is entered as the

default DMZ server.

WARNING:

DMZ servers pose a security risk. A computer designated as the

default DMZ server loses much of the protection of the firewall and

is exposed to exploits from the Internet. If compromised, the DMZ

server computer can be used to attack other computers on your

network.

The router discards incoming traffic from the Internet unless the traffic is a response to one of

your local computers or a service that you have configured in the Port Forwarding/Port

Triggering screen. Instead of discarding this traffic, you can have the router forward traffic to

one computer on your network. This computer is called the default DMZ server.

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

To set up a default DMZ server:

1.

On the WAN Setup screen, select the

Default DMZ Server

check box.

2.

Type the IP address.

3.

Click

Apply

.

Change the MTU Size

The maximum transmission unit (MTU) is the largest data packet a network device transmits.

When one network device communicates across the Internet with another, the data packets

travel through many devices along the way. If any device in the data path has a lower MTU

setting than the other devices, the data packets have to be split or “fragmented” to

accommodate the device with the smallest MTU.

The best MTU setting for NETGEAR equipment is often just the default value, and changing

the value might fix one problem but cause another. Leave MTU unchanged unless one of

these situations occurs:

•

You have problems connecting to your ISP or other Internet service, and the technical

support of either the ISP or NETGEAR recommends changing the MTU setting. These

web-based applications might require an MTU change:

-

A secure website that does not open, or displays only part of a web page

-

Yahoo email

-

MSN portal

-

America Online’s DSL service

•

You use VPN and have severe performance problems.

•

You used a program to optimize MTU for performance reasons, and now you have

connectivity or performance problems.

Note:

An incorrect MTU setting can cause Internet communication

problems such as the inability to access certain websites, frames

within websites, secure login pages, or FTP or POP servers.

If you suspect an MTU problem, a common solution is to change the MTU to 1400. If you are

willing to experiment, you can gradually reduce the MTU from the maximum value of 1500

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until the problem goes away. The following table describes common MTU sizes and

applications.

Table 2.

Common MTU sizes

MTU

Application

1500

The largest Ethernet packet size and the default value. This is the typical setting for

non-PPPoE, non-VPN connections, and is the default value for NETGEAR routers,

adapters, and switches.

1492

Used in PPPoE environments.

1472

Maximum size to use for pinging. (Larger packets are fragmented.)

1468

Used in some DHCP environments.

1460

Usable by AOL if you do not have large email attachments, for example.

1436

Used in PPTP environments or with VPN.

1400

Maximum size for AOL DSL.

576

Typical value to connect to dial-up ISPs.



To change the MTU size:

1.

Select

Advanced > Setup > WAN Setup

.

2.

In the MTU Size field, enter a new size from 64 through 1500.

3.

Click

Apply

to save your settings.

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LAN Setup

The LAN Setup screen allows configuration of LAN IP services such as Dynamic Host

Configuration Protocol (DHCP) and Routing Information Protocol (RIP).

The router is shipped preconfigured to use private IP addresses on the LAN side and to act

as a DHCP server. The router’s default LAN IP configuration is:

•

LAN IP address.

192.168.1.1

•

Subnet mask.

255.255.255.0

These addresses are part of the designated private address range for use in private networks

and should be suitable for most applications. If your network requires a different IP

addressing scheme, you can change these settings in the LAN Setup screen.

Note:

If you change the LAN IP address of the router while connected

through the browser, you are disconnected, and must open a new

connection to the new IP address and log in again.



To change the LAN settings:

1.

Select

Advanced > Setup > LAN Setup

.

2.

Enter the settings that you want to customize.

These settings are described in the following section,

LAN Setup Screen Settings

.

3.

Click

Apply

to save your settings.

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LAN Setup Screen Settings

LAN TCP/IP Setup

•

IP Address

. The LAN IP address of the router.

•

IP Subnet Mask

. The LAN subnet mask of the router. Combined with the IP address, the

IP subnet mask allows a device to know which other addresses are local to it, and which

have to be reached through a gateway or router.

•

RIP Direction

. Router Information Protocol (RIP) allows a router to exchange routing

information with other routers. This setting controls how the router sends and receives

RIP packets. Both is the default setting. With the Both or Out Only setting, the router

broadcasts its routing table periodically. With the Both or In Only setting, the router

incorporates the RIP information that it receives.

•

RIP Version

. This setting controls the format and the broadcasting method of the RIP

packets that the router sends. It recognizes both formats when receiving. By default, the

RIP function is disabled.

•

RIP-1

is universally supported. It is adequate for most networks, unless you have an

unusual network setup.

•

RIP-2

carries more information. Both RIP-2B and RIP-2M send the routing data in

RIP-2 format. RIP-2B uses subnet broadcasting. RIP-2M uses multicasting.

Use Router as DHCP Server

This check box is selected so that the router functions as a Dynamic Host Configuration

Protocol (DHCP) server.

•

Starting IP Address

. Specify the start of the range for the pool of IP addresses in the

same subnet as the router.

•

Ending IP Address

. Specify the end of the range for the pool of IP addresses in the

same subnet as the router.

Address Reservation

When you specify a reserved IP address for a computer on the LAN, that computer receives

the same IP address each time it accesses the router’s DHCP server. Assign reserved IP

addresses to servers that require permanent IP settings.

Use the Router as a DHCP Server

By default, the router functions as a DHCP 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 router. The router assigns IP addresses to

the attached computers from a pool of addresses specified in this screen. 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 router are satisfactory.