Inconsistent Device view in the ONOS CLI

Though there are no switches connected to my two node ONOS cluster, I see the "devices" CLI command output shows few devices as available

onos> devices
id=of:0000000000000001, available=true, role=NONE, type=SWITCH, mfr=Stanford University, Ericsson Research and CPqD Research, hw=OpenFlow 1.3 Reference Userspace Switch, sw=Apr 6 2015 16:10:53, serial=1, protocol=OF_13, channelId=192.168.10.50:48017
id=of:0000000000000002, available=true, role=NONE, type=SWITCH, mfr=Stanford University, Ericsson Research and CPqD Research, hw=OpenFlow 1.3 Reference Userspace Switch, sw=Apr 6 2015 16:10:53, serial=1, protocol=OF_13, channelId=192.168.10.50:48011
id=of:0000000000000003, available=false, role=NONE, type=SWITCH, mfr=Stanford University, Ericsson Research and CPqD Research, hw=OpenFlow 1.3 Reference Userspace Switch, sw=Apr 6 2015 16:10:53, serial=1, protocol=OF_13, channelId=192.168.10.50:55580
id=of:0000000000000004, available=true, role=NONE, type=SWITCH, mfr=Stanford University, Ericsson Research and CPqD Research, hw=OpenFlow 1.3 Reference Userspace Switch, sw=Apr 6 2015 16:10:53, serial=1, protocol=OF_13, channelId=192.168.10.50:48019
id=of:0000000000000005, available=true, role=NONE, type=SWITCH, mfr=Stanford University, Ericsson Research and CPqD Research, hw=OpenFlow 1.3 Reference Userspace Switch, sw=Apr 6 2015 16:10:53, serial=1, protocol=OF_13, channelId=192.168.10.50:48013
id=of:0000000000000006, available=false, role=NONE, type=SWITCH, mfr=Stanford University, Ericsson Research and CPqD Research, hw=OpenFlow 1.3 Reference Userspace Switch, sw=Apr 6 2015 16:10:53, serial=1, protocol=OF_13, channelId=192.168.10.50:55623
onos>
onos>
onos>
onos> masters
192.168.10.50: 0 devices
192.168.10.51: 0 devices
onos>
onos> nodes
id=192.168.10.50, address=192.168.10.50:9876, state=ACTIVE, updated=2m ago
id=192.168.10.51, address=192.168.10.51:9876, state=ACTIVE, updated=2m ago *