of inputs and outputs. Other interesting approaches have been researched, such as the broadcast switches or multicast switches, where the desired egress port number is tagged onto each packet and then it is sent simul- taneously to all egress ports by the switch fabric. Egress ports will buffer in their own output queues only those packets with a tag that matches their own port number. The advantage of such an approach is that as scheduling is only needed at the outputs and not over the entire switch fabric realm, this is an overall less complex system design despite the extra logic needed at each output to compare the port identifier with packet tags. Some other rather creative techniques are based on methods such as call splitting, where the traf- fic load and the number of active input lines will influence the decision of whether one or more copies of the same cell (frame/packet) will be switched in a specific time slot. 10 The overall conclusion these are generally complex approaches and some other more intelligent means must be devised in order to create larger complex switch designs. One of these approaches is to use the Banyan switch- ing network and the possibilities of augmenting it with other techniques. In the following sections, we will look at buffered switch fabrics and, more specifically, at the two main variants-namely, when the buffering occurs at the input or output. We will then look at some of the most important architectural approaches-namely, those that are based on shared memory, the buffered crossbar, and the arbitrated crossbar. The arbitrated crossbar is available based on a central- ized or distributed arrangement. 6. H. Jonathan Chao, Cheuk H. Lam, and Eiji Oki, Broadband Packet Switching Technologies: A Practical Guide to ATM Switches and IP Routers (New York: Wiley-Interscience, 2001). 7. J.J. Deegan, G. W.1 R. Luderer, and A. K. Vaidya, "Fast Packet Technology for Future Switches," AT&T Technical Journal (March- April 1989): 36-50. 8. Y. Oie, T. Suda, M. Murata, D. Kolson, and H. Mi