Is there a way to see ARP statistics under a 3750 switch? We're having an issue where it doesn't seem like the ARP table is refreshing correctly. I have a port that shows to be connected, but there's no mac address listed.
Are we really talking about the ARP table and are you sure that there should be an entry in the ARP table? There will be a listing in the ARP table only if the switch has communicated to the device on layer 3 (if the switch has pinged the device, etc, or has routing enabled and has routed packets to the device). I wonder if what you should be looking at is the mac-address-table to verify that a device is connected.
There are several things that might produce symptoms such as you describe. If the port is configured as a span port destination (or monitor port destination depending on which model of switch) then the switch sends traffic to the monitor port but does not receive traffic from the monitor port. The result is that there is a connected device but no entry in the mac-address-table. Of if for some reason the device that is connected has not sent any traffic during the period of the mac address ageing time, then the switch will have aged out the mac address in the table and not relearned it. Some devices like printers do this a lot. Or there might be a situation where there is assymetric traffic which could result in this situation (explanations of unicast flooding sometimes refer to this issue).
So there are some situations where there is a connected device but no entry in the mac-address-table.
We are pleased to announce availability of Beta software for 16.6.3.
16.6.3 will be the second rebuild on the 16.6 release train targeted
towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are
looking for early feedback from customers befor...
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