có lợi thế gây ra ít hơn (và trong một số trường hợp không có) mất, chỉ có thể làm việc với một chương trình quản lý hoạt động hàng đợi như RED. Sally Floyd duy trì một số thông tin liên quan đến kinh nghiệm thực hiện với RED trên trang web của mình. Với các sự kiện trên trang này và số lượng đáng kể lợi thế | 96 PRESENT TECHNOLOGY ECN which has the advantage of causing less and in some cases no loss can only work with an active queue management scheme such as RED. Sally Floyd maintains some information regarding implementation experiences with RED on her web page. Given the facts on this page and the significant number of well-known advantages there is reason to hope that RED or some other form of active queue management is already widely deployed and that its use is growing. In any case there is no other IETF recommendation for active queue management up to now - so if your packets are randomly dropped or marked chances are that it was done by RED or one of its variants. The ATM Available Bit Rate service ATM was an attempt to build a new network that supports multimedia applications such as pay-per-view or video conferencing through differentiated and accordingly priced service classes. It is a highly complex technology that was defined with its own three-dimensional layer model and it was supposed to provide services at all layers of the stack. Underneath it all cells - link layer data units with a fixed size of 53 bytes five of which constitute the header - are sent across fibre links. These cells are used to realize circuit-like behaviour via time division multiplexing. If for example every fifth cell along a particular set of links is devoted to a particular source destination pair the provisioned data rate can be precisely calculated this results in a strictly connection-oriented service where the connection behaves like a leased line. Cells must be small in order to enable provisioning of such services with a fine granularity. Specifically the services of ATM are as follows Constant Bit Rate CBR for real-time applications that require tightly constrained delay variation. Real-Time Variable Bit Rate rt-VBR for real-time applications that require tightly constrained delay variation and transmit with a varying data rate. Non-Real-Time Variable Bit Rate nrt-VBR
