ADTRAN 1200070L2, 1200070L1 user manual Ordering Isdn, Interoperability, Connecting to the Internet

Chapter 1: Understanding ISDN and the Express XL/XLT

Ordering ISDN

When ordering ISDN from the telephone company, request EZ-ISDN 1 (Ca- pability Package U) to ensure it is set up properly. EZ-ISDN 1 is recommend- ed by the industry for most home office/small business applications. If this is not available from your service provider or you would like more information regarding ordering ISDN, see the ADTRAN document Ordering ISDN Service User Guide part number 60000.015-8 or contact your telephone company for al- ternative line configurations. The Ordering ISDN Service User Guide is avail- able on the ADTRAN home page at http://www.adtran.com or by calling

ADTRAN.

Interoperability

The Express XL/XLT is standards based and uses PPP developed by Internet Engineering Task Force (IETF). PPP provides a standard method of transport- ing multi-protocol datagrams over point-to-point links. PPP is widely accept- ed by many ISDN bridge/router manufacturers. The Express XL/XLT will negotiate Multilink PPP when connecting both B-channels. The Bandwidth Allocation Protocol (BAP) may also negotiate, which enhances the manage- ment of adding and removing a B-channel. Data compression is also support- ed using LZS® technology from hi/fn™.

Connecting to the Internet

Internet Service Providers (ISPs) assign an IP address to use when connected to their service using PPP negotiation. This assignment is based on the as- sumption that the user has an ISDN terminal adapter running PPP async-to- sync conversion or another rate adaption where the PPP negotiation is termi- nated inside the PCs 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 Express XL/XLT permits the user to assign any IP addresses 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 XL/XLT keeps track of the computers that request services over the Internet. A web server address can

61200.070L1-1 Express XL/XLT User Manual 19