For packets it forwards, the DLR must be able to resolve ARP requests for the next hop’s IP address. The results of this resolution process are stored locally on the individual hosts’ DLR instances.

Controllers play no role in this process and are not used to distribute resulting ARP entries to other hosts.

Inactive cached entries are kept for 600 seconds, then removed. For more information about the DLR ARP resolution process, see DLR ARP Resolution Process.

  1. From the NSX Manager shell, run show cluster all to get the cluster ID.
  2. Run show cluster cluster-id to get the host ID.
  3. Run show logical-router host hostID dlr all brief to get the dlrID (Vdr Name).
  4. Run show logical-router host hostID dlr dlrID arp to get the status information for all interfaces.
nsxmgr# show logical-router host hostID dlr dlrID arp

VDR default+edge-1:1460487509 ARP Information :
Legend: [S: Static], [V: Valid], [P: Proxy], [I: Interface]
Legend: [N: Nascent], [L: Local], [D: Deleted]

Network           Mac                  Flags      Expiry     SrcPort    Interface Refcnt
-------           ---                  -----      -------    ---------  --------- ------       02:50:56:56:44:52    VI         permanent  0          570d45550000000a 1      00:50:56:a6:7a:a2    VL         147        50331657   570d45550000000a 2       02:50:56:56:44:52    VI         permanent  0          570d45550000000c 1      00:50:56:a6:ba:09    V          583        50331650   570d45550000000c 2      00:50:56:a6:84:52    VL         568        50331658   570d45550000000b 2       02:50:56:56:44:52    VI         permanent  0          570d45550000000b 1      02:50:56:56:44:52    VI         permanent  0          570d455500000002 1      00:50:56:8e:ee:ce    V          147        50331650   570d455500000002 1
Things to note:
  • All ARP entries for the DLR’s own LIFs (“I” Flag) are the same and show the same vMAC that was discussed in VXLAN Preparation Check.
  • ARP entries with the “L” Flag correspond to the VMs running on the host where the CLI command is run.
  • “SrcPort” shows the dvPort ID where the ARP entry was originated. In cases where an ARP entry was originated on another host, the dvUplink’s dvPort ID is shown. This dvPort ID can be cross-referenced with the dvUplink dvPort ID discussed in VXLAN Preparation Check.
  • The “Nascent” flag is not normally observed. It is set while the DLR is waiting for the ARP reply to arrive. Any entries with that flag set might indicate that there is a problem with ARP resolution.