Need help with the following question

(2.) Consider an M/M/oo queue. In other words, a queue with an innite number of servers. In such a queue customers never need to wait for service because there is always a server free no matter how many customers are in the system. Let /\\ > 0 denote the rate of arrivals in such a process and ,u > 0 denote the service rate of a single server. Show that a stationary distribution always exists and is given by the Poisson distribution with parameter A/p