On Thu, Mar 26, 2015 at 5:27 PM, Peter Brady <subscriptions at simonplace.net> wrote: > FWITW the switches I've lost contact with are Netgear Layer 2 and 3 > managed switches, not that brand should make a difference. Some other > Netgear WAPs are fine and all CISCO devices are fine. With a machine on > the same VLAN all is happy. > Could be asymmetric routing... Do the Netgear and Cisco devices have the same default gateway? Do the Cisco devices have SVI or vlan-interface in multiple VLANs? Do the CentOS and MAC use the same default gateway? Capture at the device: Does the SNMP request make it to $device? Does $device respond? This will tell you if you are troubleshooting the sending of the SNMP query or the SNMP response. Are the ASA rules actually in place? I've seen firewall say X is allowed at a software level but changing the order of rules and then changing back and re-pushing fix things.