One of the challenges in the interconnection of LANs and MANs to asynchronous transfer mode (ATM) networks is the support of connectionless traffic in the ATM network. A commonly proposed strategy consists of maintaining a thin, low bandwidth virtual path (VP) between each pair of gateways and requesting more bandwidth whenever a burst comes in from the LAN or MAN. Unfortunately, this strategy places a heavy burden on the ATM control processors; furthermore, it is overly conservative in the use of bandwidth. An alternative solution is proposed: on the-fly tranmission of bursts without prior bandwidth reservation. The key conditions for this scheme to work are the use of the cell loss priority (CLP) bit in the ATM cell header and the knowledge of available bandwidth on the path through bandwidth advertising. An on-the-fly strategy for connectionless traffic is described and is compared with a bandwidth renegotiation strategy.>

The authors compare three strategies, namely, reservation, on-the-fly, and hybrid, for the support of connectionless internet traffic on asynchronous transfer mode (ATM). The comparison is based on a simulation experiment in which a mix of virtual paths (some carrying connectionless traffic, some carrying connection-oriented traffic) are multiplexed on a 150 Mb/s trunk, called the bottleneck trunk. Results based on a variety of measures (cell and burst loss rates, cell delay, and burst delay) show that the on-the-fly approach, which aggressively exploits unused bandwidth, is superior to the reservation scheme, which is handicapped by the renegotiation overhead and the conservative usage of bandwidth. The hybrid scheme exhibits a performance behavior between the other two. This is a bit disappointing, considering the fact that the hybrid scheme is expected to be consistently better than both schemes. Still the hybrid scheme offers some interesting features (e.g. lower delays for the background traffic) which should be further explored by a more extensive examination of the working parameters.>

A preliminary proposal is made for a new approach to connectionless traffic handling in asynchronous transfer mode (ATM) networks. The approach is based on available bandwidth information on the virtual path (VP) periodically supplied by the network to the gateway (bandwidth advertising). The knowledge of available bandwidth allows the gateway to inject (with relatively low risk of cell loss) short bursts into the VP pipe immediately, without buffering or prior bandwidth renegotiation. The performance benefits of the proposed scheme with respect to more conventional schemes are evaluated in a simple network example.>

One of the challenges in the interconnection of LANs and MANs to ATM is the support of connectionless traffic in the ATM network. Several solutions have been proposed. A popular strategy seems to be that of maintaining a 'thin' (i.e. low bandwidth) VP (virtual path) between each pair of gateways, and of requesting more bandwidth whenever a burst comes in from the LAN or MAN. Unfortunately, this strategy places a heavy burden on the ATM control processors; furthermore, it is overly conservative in the use of bandwidth. An alternative solution is proposed: on-the-fly transmission of bursts, without prior bandwidth reservation. The key conditions for this scheme to work are the use of the CLP (cell loss priority) bit, and the knowledge of available bandwidth on the path through 'bandwidth advertising'. An 'on-the-fly' strategy for connectionless traffic is described and is compared with a bandwidth renegotiation strategy.>