This document provides requirements for advanced bonding of multiple digital subscriber lines (DSL) to transport ATM streams. The specifications of this standard provide a complete description of startup@ operational@ and contingency modes of operation@ which allows for interoperability between vendors. This document includes the following types of requirements@ recommendations@ and information for defined DSL systems@ including: ? Higher-layer transport-independent requirements; and ? Higher-layer transport-dependent -- e.g.@ ATM -- requirements. Purpose The purpose of this standard is to assist manufacturers@ providers@ and users of products on how to use multiple DSL lines to carry a single ATM payload stream. In order to satisfy this purpose@ requirements and guidelines are provided. When the requirements contained in this standard are satisfied@ the bonding system is standard compliant. The standard is written to satisfy the following bonding objectives: 1. Bonding shall support dynamic removal and restoration of pairs without human intervention. 2. Bonding shall support disparate data rates@ up to a ratio of 4-to-1 (fastest to slowest)@ amongst its pairs. 3. The protocol shall allow bonding of 2-32 pairs. 4. The protocol shall permit bonding of randomly assigned ports on an access node. 5. The protocol shall be PHY independent. 6. The protocol shall incur a maximum overall one-way bonding delay of 2 ms. In order for implementations compliant to this standard to be interoperable between vendors@ an initialization procedure@ a payload tagging method@ and OAM capability are provided. The specification begins with a list of normative references followed by a list of definitions and acronyms.