User's Manual  for
PLANET ISDN Router Product

IRT-401


Chapter 2. ISDN Line and Internet Service Options

This chapter provides information on the IRT-401 functions that you should be familiar with before you order your ISDN line and Internet service.

There are several service options that you can order through your ISDN line provider and Internet Service Provider (ISP). The information in this chapter is provided so that you may make informed decisions while ordering your services, based on the IRT-401 functions that you wish to use.

Topics covered:


  1. Internet Service Provider Related Options

An ISP generally offers two types of accounts, a Single User Account (SUA), and a LAN Access (Multiple User) Account (MUA). Typically, if there are multiple users on a LAN wanting concurrent Internet access, you will usually have to subscribe to a "multipleIP address or a Class C sub-network from an ISP. The Single User Account on the other hand offers customers the benefits as having a Class C address, but only paying for a 'single' IP address, thus saving on subscription fees over MUA's. An SUA used in conjunction with the IRT-401's NAT function will provide similar functionality to an MUA.

The IRT-401 supports both types of accounts. The advantages and disadvantages of using a Single User Account are described below. Please review this information before deciding what type of service you wish to order.

Network Address Translation (NAT) is designed to allow multiple users on the LAN to access Internet simultaneously using the Single User Account. In addition to cost saving, NAT is also useful in areas in which security and convenience are a concern.

Convenience

It is convenient because users do not have to change their workstation IP addresses already in use, while with a "multi-user" account you do. Also, you do not have to register an IP address to access the Internet through the "single-useraccount, while with a "multi-useraccount you do.

Security

In order for the outside world to access the TCP/IP servers on the LAN, IRT-401 allows a list of internal IP addresses to be associated with FTP, Telnet, HTTP, and Email servers. Traffic destined for the servers on the list are forwarded only to the specified IP addresses. The inbound traffic distribution works only for static IP address arrangement where you can register an IP address against the domain names. This provides your network with an effective firewall against unwanted intrusions.

There are some disadvantages to using the NAT application:

1.If the ISDN connection drops (e.g., because of an idle time-out), most likely that upon reconnection you will get a different IP address assigned. For example, if you are using a web browser and the connection drops because of an idle time-out, when you click on a link, you might get an error message because you now have a different IP address.

2.Certain applications, like some UDP-based Internet games and chat client programs, will work unreliably or not at all when using NAT. This is because these programs will report their private IP address to the IRT-401 instead of to the dynamically assigned address of the PC. Because of this, the IRT-401 does not know where to route the packets, consequently, they are not forwarded to the PC.

Note: NAT is available to Internet connection only. The Intranet connection is not affected by the Internet NAT setting.

If you are subscribing to a single user account, your ISP will either supply you with a static IP address or will dynamically assign an address at login. IRT-401 will accept the dynamically assigned IP address for its ISDN interface and update the routing table accordingly. Both the assigned IP address and the associated routing table entry are deleted when the session is closed. The NAT feature is required for multiple LAN users to access the Internet using the Single User account.

  1. ISDN Line Provider Related Options

The Multilink PPP (MP) is a standardized extension of the PPP (Point-to-Point Protocol) standard. It allows the IRT-401 to combine 2 B channels into a 'multilink bundle' so that data can be sent at higher rates. Multilink PPP can combine your two 64Kbps channels into a virtual, single 128Kbps connection.

If you want to use this function, please make sure your ISP's router supports MP.

Callback is available on ISDN circuits. It allows a remote device to request a return call from your IRT-401. This means that when an incoming call is received on a circuit, the IRT-401 drops that call and calls back the originating router. This allows you to maintain centralized billing, which reduces the hassles of reimbursement. Callback also provides additional security.

If you want to use this function, please be sure your provider's router supports a callback function.

There are two types of callback options:

  1. Caller ID (CLID)
  2. CLID enables the IRT-401 to check the phone number of an incoming call. The IRT-401 checks the phone number against a list of acceptable numbers. If the phone number is validated, the connection is dropped and the IRT-401 calls the number back. If the number is not validated, the IRT-401 drops the call and does not call the number back. Using CLID, the caller is not charged for the phone call

  3. PPP
  4. If CLID is disabled in the IRT-401, a call is accepted by the Listener circuit and Callback is negotiated using PPP authentication. This method will incur a small cost at the originating end since the call has to be accepted before Callback is negotiated. If the PPP negotiation fails, the call is dropped.

The IRT-401 features MSN, which allows multiple telephone numbers to be assigned to a single ISDN connection. This allows you to assign specific numbers to specific devices. Your ISDN line provider's MSN option is supported by the IRT-401.

The IRT-401 provides connection to two analog devices (e.g. telephones, fax, modems). It is possible to give each device a separate number through MSN, allowing calls to be routed to the correct analog device (1 MSN number per analogue port).

  1. Ordering Your ISDN Line / Internet Account

This section outlines what information you need to order your ISDN line and Internet Account. A worksheet is provided for easy reference.

When you order your ISDN line and Internet Account, you will also need to get some information from your providers. Entering this information will be of great assistance when you are configuring your IRT-401, and will provide you with a handy reference for future use.

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IRT-401 Setup Worksheet

Information you need to give to your ISDN Line Provider

___ Yes

___ No

___ Yes

___ No

Information your ISDN Line Provider needs to give you

____________________

____________________

____________________

Information you need to give to your Internet Service Provider (ISP)

___ Yes

___ No

___ Yes

___ No

___ Yes

___ No

Information your Internet Service Provider (ISP) needs to give you

____________________

____________________

____________________

    ____________________

___PAP

___CHAP

____________________ to ____________________ (M.U.A Only)

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____________________ & ____________________

____________________

____________________

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Copyright (C) 1999 PLANET Technlogy Corporation