On-demand routing protocols for mobile ad-hoc networks register unexpected performance behavior when multiple data streams are sent to a common destination. This scenario is common when a MANET is connected to the Internet through common gateways, or used in similar cases. The AODV out-performs DSR in the normal situation but in the constrained situation DSR out-performs AODV. The degradation is as severe as 30% in AODV, whereas DSR degrades marginally 10% as observed through simulation in Glomosim. This problem has been analysed in both on-demand protocols, and improvements have been suggested in a proposed local congestion control algorithm.