While designing ASON/ASTN systems, the bandwidth requirements for signalling networks should be made clear in advance. An analysis model based on queueing theory is proposed, and queueing delay is used as the performance metric. A simulation model and an analytical model are presented. These models can be used to guide the design of ASON/ASTN signalling networks. We analyze the bandwidth requirements for ASON/ASTN signalling networks with RSVP-TE protocol. The analysis results show that, the main signalling network bandwidth consuming packets are RSVP-TE soft state refresh packets and establishing/releasing connection packets. The upper bound of bandwidth requirement of soft state refresh can be determined directly. But the establishing/releasing connection process is a stochastic process, and its bandwidth requirement depends mainly on mean arrival rate of the signalling packets at the rush hour, or the number of concurrent requests.