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Vishwajit25
Contributor
Contributor
‎04-04-2017 05:54 AM

Host cannot communicate

After patching ESXi 6.5 with the latest update the following warning "Host cannot communicate with all other nodes in vSAN enabled cluster" on all the hosts in vSan(6.5) cluster. It was bug reported with 6.0 which is fixed in update 2. Any update on 6.5?

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3 Replies
GreatWhiteTec
VMware Employee
VMware Employee
‎04-04-2017 06:13 AM

Can you provide more info about the "bug"? Also, how is your network set up? 2 Nics, active/passive? vDS or VSS? NIOC? This traffic is going through multicast, and often times the network partition occurs due to an active/active setup where the traffic goes to different switches and multicast communication is not possible.

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Vishwajit25
Contributor
Contributor
‎04-04-2017 06:23 AM

bug reported as per VMware its fixed in update 2.

https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=21432...

Both NICs are active/active and VSS.

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GreatWhiteTec
VMware Employee
VMware Employee
‎04-04-2017 06:47 AM

Multicast traffic is distributed at the point of path divergence, in this case your switches.

Assuming that all your NIC As connect to SW 1, and all NIC Bs connect to SW 2: You may experience network partitioning if some of your hosts are using NIC A, while others are using NIC B for vSAN traffic, since multicast is distributed at the switch level.

The recommendation is to have the interfaces in active/passive mode, given that vSAN traffic was not designed for load balancing but High Availability rather, although you may achieve some LB using LACP teaming.

The bug you reported was a cosmetic bug on 6.0 1b and has been carried over to 6.5 release.