how to monitor switches and increase the polling time

Hi, since we are monitoring ober 300 servers at a time in a custer, we want to know and analyser the network traffic in ethernet and infiniband switch .how we can monitor it using xymon system monitoring.os is rhel 5.2 and xymon version is 4.2.2 Practical problem happening is that some of the nodes reboots but xymon doesnt show it. it may be because that happens in betwwen the polling period of the server. how to overcome this issue?same thing happens for disk and ncpu and external tests also that it does not identify and show these problems as it must be occuring in betwwn polling period .How to make it fast as ganglia

-- Pankaj V. Dorlikar