0 Replies Latest reply on Mar 13, 2019 6:29 PM by scotia

    ESXi 6.7 using same source MAC for CDP on different physical nic

    scotia Lurker

      Hi,

       

      I'm seeing MAC flapping errors on my Cisco switch.  An ESXi host is attached with four interfaces.  No LACP or port-channel is configured.  In any case CDP is a per-physical interface protocol (which should be advertised on physical interfaces and NOT bundles, etc.).

       

      The problem is that the host is sending CDP packets from the same virtual MAC down two interfaces (although the other two interfaces are fine).

       

      Here are the four CDP packets coming from ESX to the Cisco switch (note that the MAC flap error only complains about two of the four ports)

       

      Mar  9 05:13:55.329: CDP-PA: Packet received from esx-01.local on interface GigabitEthernet0/6

      Mar  9 05:13:55.329: **Entry NOT found in cache**

      Mar  9 05:13:55.329: CDP-EV: Packet Received from esx-01.local with capability = 8 and Platform string = VMware ESX on interface GigabitEthernet0/6

      Mar  9 05:13:55.329: CDP-EV: Powernet Event request received on interface GigabitEthernet0/6

      Mar  9 05:13:55.329: CDP-EV: New Neighbor discovered, notified registered clients on interface GigabitEthernet0/6

      Mar  9 05:13:55.329: CDP-PA: Packet received from esx-01.local on interface GigabitEthernet0/4

      Mar  9 05:13:55.329: **Entry NOT found in cache**

      Mar  9 05:13:55.329: CDP-EV: Packet Received from esx-01.local with capability = 8 and Platform string = VMware ESX on interface GigabitEthernet0/4

      Mar  9 05:13:55.329: CDP-EV: Powernet Event request received on interface GigabitEthernet0/4

      Mar  9 05:13:55.329: CDP-EV: New Neighbor discovered, notified registered clients on interface GigabitEthernet0/4

      Mar  9 05:13:55.329: CDP-PA: Packet received from esx-01.local on interface GigabitEthernet0/3

      Mar  9 05:13:55.329: **Entry NOT found in cache**

      Mar  9 05:13:55.329: CDP-EV: Packet Received from esx-01.local with capability = 8 and Platform string = VMware ESX on interface GigabitEthernet0/3

      Mar  9 05:13:55.329: CDP-EV: Powernet Event request received on interface GigabitEthernet0/3

      Mar  9 05:13:55.329: CDP-EV: New Neighbor discovered, notified registered clients on interface GigabitEthernet0/3

      Mar  9 05:13:55.337: CDP-PA: Packet received from esx-01.local on interface GigabitEthernet0/2

      Mar  9 05:13:55.337: **Entry NOT found in cache**

      Mar  9 05:13:55.337: CDP-EV: Packet Received from esx-01.local with capability = 8 and Platform string = VMware ESX on interface GigabitEthernet0/2

      Mar  9 05:13:55.337: CDP-EV: Powernet Event request received on interface GigabitEthernet0/2

      Mar  9 05:13:55.337: CDP-EV: New Neighbor discovered, notified registered clients on interface GigabitEthernet0/2

      Mar  9 16:13:55.363 AEDST: %SW_MATM-4-MACFLAP_NOTIF: Host 0050.565c.13e7 in vlan 1 is flapping between port Gi0/4 and port Gi0/3

       

      Here is a pcap of the two packets on Gi0/3 and Gi0/4.  Note the identical source MAC (00:50:56:5c:13:e7), however the advertised ports are different.

       

      14:43:55.361048 00:50:56:5c:13:e7 (oui Unknown) > 01:00:0c:cc:cc:cc (oui Unknown), 802.3, length 164: LLC, dsap SNAP (0xaa) Individual, ssap SNAP (0xaa) Command, ctrl 0x03: oui Cisco (0x00000c), pid CDP (0x2000), length 156: CDPv2, ttl: 1

      80s, checksum: 0x1812 (unverified), length 156

              Device-ID (0x01), value length: 21 bytes: 'esx-01.local'

              Address (0x02), value length: 13 bytes: IPv4 (1) 0.0.0.0

              Port-ID (0x03), value length: 6 bytes: 'vmnic1'

              Capability (0x04), value length: 4 bytes: (0x00000008): L2 Switch

              Version String (0x05), value length: 21 bytes:

                Releasebuild-11675023

              Platform (0x06), value length: 10 bytes: 'VMware ESX'

              VTP Management Domain (0x09), value length: 1 byte: '^@'

              Duplex (0x0b), value length: 1 byte: full

              MTU (0x11), value length: 4 bytes: 9000 bytes

              AVVID untrusted ports CoS (0x13), value length: 1 byte: 0x00

              AVVID trust bitmap (0x12), value length: 1 byte: 0x00

              System Name (0x14), value length: 21 bytes: 'esx-01.local'

      14:44:55.360698 00:50:56:5c:13:e7 (oui Unknown) > 01:00:0c:cc:cc:cc (oui Unknown), 802.3, length 164: LLC, dsap SNAP (0xaa) Individual, ssap SNAP (0xaa) Command, ctrl 0x03: oui Cisco (0x00000c), pid CDP (0x2000), length 156: CDPv2, ttl: $

      80s, checksum: 0x1811 (unverified), length 156

              Device-ID (0x01), value length: 21 bytes: 'esx-01.local'

              Address (0x02), value length: 13 bytes: IPv4 (1) 0.0.0.0

              Port-ID (0x03), value length: 6 bytes: 'vmnic2'

              Capability (0x04), value length: 4 bytes: (0x00000008): L2 Switch

              Version String (0x05), value length: 21 bytes:

                Releasebuild-11675023

              Platform (0x06), value length: 10 bytes: 'VMware ESX'

              VTP Management Domain (0x09), value length: 1 byte: '^@'

              Duplex (0x0b), value length: 1 byte: full

              MTU (0x11), value length: 4 bytes: 9000 bytes

              AVVID untrusted ports CoS (0x13), value length: 1 byte: 0x00

              AVVID trust bitmap (0x12), value length: 1 byte: 0x00

              System Name (0x14), value length: 21 bytes: 'esx-01.local'

       

      Thoughts?

      Thanks,

      Scott