Session concentration can be used to:
Reducing sessions can minimize network bandwidth use, improve sever performance, and save time an money (when fewer sessions are being established across a slow or expensive links).
InRSs and OutRSs provide intra-site session concentration by controlling the flow of messages within sites. Site gates provide intra-site session concentration by controlling the flow of messages between sites.
Session concentration places an additional load on MSMQ servers. To compensate for this increased load, you may need to install additional MSMQ routing servers.
In a small enterprise, a PSC or the PEC could function as the InRS or OutRS for each MSMQ independent client in the site. However, to provide redundancy, each independent client should also be configured to use the site BSC as an InRS and/or OutRS.