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Figure 17

Network Setting

>

Broadband > 3G Backup

The following table describes the labels in this screen.

Table 6

Network Setting

>

Broadband > 3G Backup

LABEL

DESCRIPTION

General

3G Backup

Select

Enable

to have the Device use the 3G connection as your WAN or a backup when the

wired WAN connection fails.

Card

description

This field displays the manufacturer and model name of your 3G card if you inserted one in

the Device. Otherwise, it displays

N/A

.

Username

Type the user name (of up to 64 ASCII printable characters) given to you by your service

provider.

Password

Type the password (of up to 64 ASCII printable characters) associated with the user name

above.

PIN

A PIN (Personal Identification Number) code is a key to a 3G card. Without the PIN code,

you cannot use the 3G card.

If your ISP enabled PIN code authentication, enter the 4-digit PIN code (0000 for example)

provided by your ISP. If you enter the PIN code incorrectly, the 3G card may be blocked by

your ISP and you cannot use the account to access the Internet.

If your ISP disabled PIN code authentication, leave this field blank.

Dial string

Enter the phone number (dial string) used to dial up a connection to your service provider’s

base station. Your ISP should provide the phone number.

For example, *99# is the dial string to establish a GPRS or 3G connection in Taiwan.

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4.5

WAN Technical Reference

This section provides some technical background information about the topics covered in this

chapter.

4.5.1

Encapsulation

Be sure to use the encapsulation method required by your ISP. The Device supports the following

methods.

4.5.1.1

ENET ENCAP

The MAC Encapsulated Routing Link Protocol (ENET ENCAP) is only implemented with the IP

network protocol. IP packets are routed between the Ethernet interface and the WAN interface and

then formatted so that they can be understood in a bridged environment. For instance, it

encapsulates routed Ethernet frames into bridged ATM cells. ENET ENCAP requires that you specify

APN

Enter the APN (Access Point Name) provided by your service provider. Connections with

different APNs may provide different services (such as Internet access or MMS (Multi-Media

Messaging Service)) and charge method.

You can enter up to 32 ASCII printable characters. Spaces are allowed.

Obtain an IP

Address

Automatically

Select this option If your ISP did not assign you a fixed IP address.

Use the

following static

IP address

Select this option If the ISP assigned a fixed IP address.

IP Address

Enter your WAN IP address in this field if you selected

Use the following static IP

address

.

Obtain DNS

info

dynamically

Select this to have the Device get the DNS server addresses from the ISP automatically.

Use the

following static

DNS IP address

Select this to have the Device use the DNS server addresses you configure manually.

Primary DNS

server

Enter the first DNS server address assigned by the ISP.

Secondary DNS

server

Enter the second DNS server address assigned by the ISP.

Connection

Select

Keep Alive

if you do not want the connection to time out.

Select

Connect on Demand

if you do not want the connection up all the time and specify

an idle time-out in the

Max Idle Timeout

field.

Max Idle

Timeout

This value specifies the time in minutes that elapses before the Device automatically

disconnects from the ISP.

Apply

Click

Apply

to save your changes back to the Device.

Cancel

Click

Cancel

to return to the previous configuration.

Table 6

Network Setting

>

Broadband > 3G Backup (continued)

LABEL

DESCRIPTION

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a gateway IP address in the

Gateway IP Address

field in the wizard or WAN screen. You can get

this information from your ISP.

4.5.1.2

PPP over Ethernet

The Device supports PPPoE (Point-to-Point Protocol over Ethernet). PPPoE is an IETF Draft standard

(RFC 2516) specifying how a personal computer (PC) interacts with a broadband modem (DSL,

cable, wireless, etc.) connection. The PPPoE option is for a dial-up connection using PPPoE.

For the service provider, PPPoE offers an access and authentication method that works with existing

access control systems (for example RADIUS).

One of the benefits of PPPoE is the ability to let you access one of multiple network services, a

function known as dynamic service selection. This enables the service provider to easily create and

offer new IP services for individuals.

Operationally, PPPoE saves significant effort for both you and the ISP or carrier, as it requires no

specific configuration of the broadband modem at the customer site.

By implementing PPPoE directly on the Device (rather than individual computers), the computers on

the LAN do not need PPPoE software installed, since the Device does that part of the task.

Furthermore, with NAT, all of the LANs’ computers will have access.

4.5.1.3

PPPoA

PPPoA stands for Point to Point Protocol over ATM Adaptation Layer 5 (AAL5). A PPPoA connection

functions like a dial-up Internet connection. The Device encapsulates the PPP session based on

RFC1483 and sends it through an ATM PVC (Permanent Virtual Circuit) to the Internet Service

Provider’s (ISP) DSLAM (Digital Subscriber Line (DSL) Access Multiplexer). Please refer to RFC 2364

for more information on PPPoA. Refer to RFC 1661 for more information on PPP.

4.5.1.4

RFC 1483

RFC 1483 describes two methods for Multiprotocol Encapsulation over ATM Adaptation Layer 5

(AAL5). The first method allows multiplexing of multiple protocols over a single ATM virtual circuit

(LLC-based multiplexing) and the second method assumes that each protocol is carried over a

separate ATM virtual circuit (VC-based multiplexing). Please refer to RFC 1483 for more detailed

information.

4.5.2

Multiplexing

There are two conventions to identify what protocols the virtual circuit (VC) is carrying. Be sure to

use the multiplexing method required by your ISP.

VC-based Multiplexing

In this case, by prior mutual agreement, each protocol is assigned to a specific virtual circuit; for

example, VC1 carries IP, etc. VC-based multiplexing may be dominant in environments where

dynamic creation of large numbers of ATM VCs is fast and economical.

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LLC-based Multiplexing

In this case one VC carries multiple protocols with protocol identifying information being contained

in each packet header. Despite the extra bandwidth and processing overhead, this method may be

advantageous if it is not practical to have a separate VC for each carried protocol, for example, if

charging heavily depends on the number of simultaneous VCs.

4.5.3

VPI and VCI

Be sure to use the correct Virtual Path Identifier (VPI) and Virtual Channel Identifier (VCI) numbers

assigned to you. The valid range for the VPI is 0 to 255 and for the VCI is 32 to 65535 (0 to 31 is

reserved for local management of ATM traffic). Please see the appendix for more information.

4.5.4

IP Address Assignment

A static IP is a fixed IP that your ISP gives you. A dynamic IP is not fixed; the ISP assigns you a

different one each time. The Single User Account feature can be enabled or disabled if you have

either a dynamic or static IP. However the encapsulation method assigned influences your choices

for IP address and ENET ENCAP gateway.

IP Assignment with PPPoA or PPPoE Encapsulation

If you have a dynamic IP, then the

IP Address

and

Gateway IP Address

fields are not applicable

(N/A). If you have a

Static IP Address

assigned by your ISP, then they should also assign you a

Subnet Mask

and a

Gateway IP Address

.

IP Assignment with RFC 1483 Encapsulation

In this case the IP address assignment must be static.

IP Assignment with ENET ENCAP Encapsulation

In this case you can have either a static or dynamic IP. For a static IP you must fill in all the

IP

Address

and

Gateway IP Address

fields as supplied by your ISP. However for a dynamic IP, the

Device acts as a DHCP client on the WAN port and so the

IP Address

and

Gateway IP Address

fields are not applicable (N/A) as the DHCP server assigns them to the Device.

4.5.5

Nailed-Up Connection (PPP)

A nailed-up connection is a dial-up line where the connection is always up regardless of traffic

demand. The Device does two things when you specify a nailed-up connection. The first is that idle

timeout is disabled. The second is that the Device will try to bring up the connection when turned

on and whenever the connection is down. A nailed-up connection can be very expensive for obvious

reasons.

Do not specify a nailed-up connection unless your telephone company offers flat-rate service or you

need a constant connection and the cost is of no concern.

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4.5.6

NAT

NAT (Network Address Translation - NAT, RFC 1631) is the translation of the IP address of a host in

a packet, for example, the source address of an outgoing packet, used within one network to a

different IP address known within another network.

4.6

Traffic Shaping

Traffic Shaping is an agreement between the carrier and the subscriber to regulate the average rate

and fluctuations of data transmission over an ATM network. This agreement helps eliminate

congestion, which is important for transmission of real time data such as audio and video

connections.

Peak Cell Rate (PCR) is the maximum rate at which the sender can send cells. This parameter may

be lower (but not higher) than the maximum line speed. 1 ATM cell is 53 bytes (424 bits), so a

maximum speed of 832Kbps gives a maximum PCR of 1962 cells/sec. This rate is not guaranteed

because it is dependent on the line speed.

Sustained Cell Rate (SCR) is the mean cell rate of each bursty traffic source. It specifies the

maximum average rate at which cells can be sent over the virtual connection. SCR may not be

greater than the PCR.

Maximum Burst Size (MBS) is the maximum number of cells that can be sent at the PCR. After MBS

is reached, cell rates fall below SCR until cell rate averages to the SCR again. At this time, more

cells (up to the MBS) can be sent at the PCR again.

If the PCR, SCR or MBS is set to the default of "0", the system will assign a maximum value that

correlates to your upstream line rate.

The following figure illustrates the relationship between PCR, SCR and MBS.

Figure 18

Example of Traffic Shaping

4.6.1

ATM Traffic Classes

These are the basic ATM traffic classes defined by the ATM Forum Traffic Management 4.0

Specification.