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On my ESXi 5.5 host I have 3 VLAN's plus one management (non-VLAN) LAN. When I print the arp cache (as show below) I notice that only the management LAN addresses are show (192.168.1.x). How do I ask ESXi to show the arp entries for the other VLAN's?

~ # esxcli network ip neighbor list
Neighbor       Mac Address        Vmknic    Expiry  State  Type   
-------------  -----------------  ------  --------  -----  -------
192.168.1.73   00:24:d7:97:5f:f9  vmk0    1188 sec         Unknown
192.168.1.1    d4:ca:6d:34:db:57  vmk0     963 sec         Unknown
192.168.1.2    a0:cf:5b:e7:19:d6  vmk0     831 sec         Unknown
192.168.1.29   00:0c:29:f0:36:a5  vmk0    1168 sec         Unknown
192.168.1.31   00:0c:29:11:6a:34  vmk0    1183 sec         Unknown
192.168.1.20   00:0c:29:46:bb:03  vmk0     755 sec         Unknown
192.168.1.16   00:11:32:3a:5a:22  vmk0    1042 sec         Unknown
~ #

For example, I have a VM guest on VLAN id 2 (192.168.2.x) and numerous physical neighbours on that VLAN, yet they don't appear above.

TSG
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2 Answers2

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Can you give more information about the actual networking issue you're facing?

I just ran the same command on one of my busy systems and see physical information on the management and storage interfaces; nothing related to the guest networks:

[root@c2-esx1:~] esxcli network ip neighbor list
Neighbor       Mac Address        Vmknic    Expiry  State  Type
-------------  -----------------  ------  --------  -----  -------
172.16.8.22    a0:d3:c1:04:66:0c  vmk0     863 sec         Unknown
172.16.8.23    f0:92:1c:18:af:90  vmk0     348 sec         Unknown
172.16.8.19    0c:c4:7a:64:bb:6a  vmk0    1187 sec         Unknown
172.16.8.65    00:50:56:ae:09:f2  vmk0    1169 sec         Unknown
172.16.8.1     00:1c:73:2c:39:29  vmk0    1190 sec         Unknown
172.16.8.3     00:1c:73:20:8e:d6  vmk0     705 sec         Unknown
172.16.8.12    00:50:56:84:2f:bb  vmk0    1163 sec         Unknown
172.16.8.8     00:0c:29:ed:f3:21  vmk0     700 sec         Unknown
192.168.77.3   00:1c:73:20:8e:d6  vmk3     730 sec         Unknown
192.168.77.12  9c:b6:54:96:47:b0  vmk3     901 sec         Unknown
192.168.77.16  3c:a8:2a:25:3d:74  vmk3     695 sec         Unknown
192.168.77.18  00:02:c9:4f:29:05  vmk3     759 sec         Unknown
192.168.71.22  00:e0:ed:56:29:95  vmk4    1175 sec         Unknown
192.168.71.21  00:e0:ed:56:29:94  vmk4    1178 sec         Unknown
192.168.71.20  00:e0:ed:56:29:94  vmk4    1181 sec         Unknown
ewwhite
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1

ARP resolves ip addresses to MAC addresses on behalf of hosts needing to communicate with other hosts on an Ethernet network.

The ESXi host doesn't communicate with the guest virtual machines and would have no need to ARP for any of the virtual machines, and therefore shouldn't have any ARP entries for the guest virtual machines.

The virtual switch is like a physical switch. It switches/forwards traffic to and from the virtual machines (or more precisely to ports and port groups to which the virtual machines are connected). At no time in that process does the host need to resolve the ip addresses to the MAC addresses of the virtual machines, therefore there should be no ARP entries for the virtual machines in the ARP cache of the host.

joeqwerty
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