Using Quality of Service can be Simple: Arequipa with Renegotiable ATM Connections

We have modi ed the popular Mbone toolVic (VIdeo Conferencing) to useArequipa (Application REQuested IP over ATM). The latter enables applications and in particular Vic, to request a direct ATM connection for its exclusive use and to directly control the tra c parameters of this connection. We have also implemented ATM Forum's UNI4.0 signaling and ITU-T's connection modi cation recommendation Q.2963.1, on end-systems as well as on switches. This implementation, coupled with the Arequipa mechanism, allowed Vic to negotiate and renegotiate ATM bandwidth at will, at run time. We describe how Vic accomplished that over the ATM WAN of SWISSCOM, transferring live video from Lausanne to Basel and Z urich over switched, renegotiable ATM connections. To our knowledge, this was the rst time any application had the capacity to tune ATM tra c parameters at run time.