Chapter 1. Understanding ISDN and the Express 4100/4110
61200176L2-1 Express 4100/4110 User Manual 1-13

Ordering ISDN

When ordering ISDN from the telephone company, request EZ-ISDN 1
(Capability Package U) to ensure it is set up properly. EZ-ISDN 1 is rec-
ommended by the industry for most home office/small business applica-
tions. If this is not available from your service provider or you would
like more information regarding ordering ISDN, see the ADTRAN docu-
ment Ordering ISDN Se rvice User Guide part number 60000.015-8 or con-
tact your telephone company for alternative line configurations. The
Orderi ng ISDN Servi ce User Guide is availab le on the ADTRAN home p age
at http://www.adtran.com or by calling ADTRAN.

Interoperability

The Express 4100/4110 is standards based and uses PPP developed by
Internet Engineering Task For ce (IETF). PPP provides a standard method
of transporting multiprotocol datagrams over point-to-point links. PPP is
widely accepted by many ISDN bridge/router manufacturers. The
Express 4100/4110 will negotiate Multilink PPP when connecti ng both B-
channels. The Bandwidth Allocation Protocol (BAP) may also negotiate,
which enhances the management of adding and removing a B-channel.
Data compression is also supported using LZS® technolo gy from hi/fn™.

Connecting to the Internet

Internet Service Providers (ISPs) assign an IP address to use when con-
nected to their service using PPP negotiation. This ass ignment is based
on the assumption that the user has an ISDN terminal adapter running
PPP async-to-sync conversion or another rate ad aption where the PPP
negotiation is terminated inside the PC’s IP stack. However, if an ISDN-
Ethernet gateway device is used, the ISP must preassign the customer a
subnet which uses multiple IP addresses. This may result in a much
higher cost to the user.
The Expr ess 410 0/4110 permits the user to assign any IP addr esses to the
unit and computers. Operations on the network can occur normally. In
fact, one B-channel can connect to the ISP using NAT while the other B-
channel connects to another “private” or “fake” network. All packets
transmitted or received over the ISP connection are translated. The
Express 4100/4110 keeps track of the computers that request services
over the Internet. A web server address can be assigned under the Con-