High speed switching of communications links without interrupting ATM cell traffic

摘要

In a mobile ATM communications network, upstream ATM cells and downstream ATM cells are transmitted between a mobile site and a fixed site over a first communication link and a handoff request message is sent from the mobile site to the fixed site when the first communication link is likely to become unavailable. In response, the upstream ATM cells are held in a first buffer and the location of a cell that is to be transmitted first when transmission of upstream cells is resumed is determined and an address pointer indicating that location is stored in a first memory. An end-of-stream OAM cell is sent from the mobile site to the fixed site over the first communication link, so that in the fixed site, the downstream ATM cells are held in a second buffer and the location of a cell within the second buffer which is to be transmitted first when transmission of downstream cells is resumed is determined and an address pointer indicating that location is stored in a second memory. A second communication link is then established between the mobile and fixed sites, and transmission of upstream ATM cells is resumed, starting with a location of the first buffer specified by the address pointer in the first memory and transmission of downstream ATM cells is resumed, starting with a location of the second buffer specified by the address pointer in the second memory.