05-01-2018 11:55 AM - edited 03-08-2019 02:51 PM
We have noticed recently that there is one switchport that will show TONS of MAC addresses, many more than could be possible. The client connected to that port is a 2017 MacBook Pro, connected to LAN through a BenQ monitor w/ a built-in NIC. Shut/no shut-ing the port clears the mac address table entries, but eventually (within a day or two) the entries will creep back up. I have no idea why this might be happening, other than a faulty NIC in the monitor. Has anyone seen this before or have an idea what's going on here? Here is a small section of the `sh mac address-table` output:
20 0000.0000.0001 STATIC Gi3/0/11 20 0000.0000.0002 STATIC Gi3/0/11 20 0000.0000.0009 STATIC Gi3/0/11 20 0000.0000.000c STATIC Gi3/0/11 20 0000.0000.0048 STATIC Gi3/0/11 20 0000.0000.007d STATIC Gi3/0/11 20 0000.0000.008d STATIC Gi3/0/11 20 0000.0000.0097 STATIC Gi3/0/11 20 0000.0000.00b9 STATIC Gi3/0/11 20 0000.0000.00bc STATIC Gi3/0/11 20 0000.0000.00cb STATIC Gi3/0/11 20 0000.0000.00f3 STATIC Gi3/0/11 20 0000.0000.0130 STATIC Gi3/0/11 20 0000.0000.0164 STATIC Gi3/0/11 20 0000.0000.0275 STATIC Gi3/0/11 20 0000.0000.0278 STATIC Gi3/0/11 20 0000.0000.0331 STATIC Gi3/0/11 20 0000.0000.0361 STATIC Gi3/0/11 20 0000.0000.0363 STATIC Gi3/0/11 20 0000.0000.0373 STATIC Gi3/0/11 20 0000.0000.0377 STATIC Gi3/0/11 20 0000.0000.0402 STATIC Gi3/0/11 20 0000.0000.0436 STATIC Gi3/0/11 20 0000.0000.0461 STATIC Gi3/0/11 20 0000.0000.0462 STATIC Gi3/0/11 20 0000.0000.0464 STATIC Gi3/0/11 20 0000.0000.046d STATIC Gi3/0/11 20 0000.0000.0470 STATIC Gi3/0/11 20 0000.0000.055f STATIC Gi3/0/11
05-01-2018 02:40 PM
05-01-2018 02:57 PM
As I was reading the description in this post I was developing a theory that the host was ARPing for every destination that it wanted to access (perhaps misconfigured default gateway). But when I looked at the output I see that these entries are static entries and so not the result of ARP from the host. I do not have a good theory about what creates these static entries.
HTH
Rick
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