topic Re: ESXi 2NICs setting in ESXi Discussions

ESXi 2NICs setting

olaq — Tue, 18 Jul 2023 03:55:47 GMT

Hi Support Team

Three ESXi hosts, each with two network cards connected to two Cisco switches.

The ESXi vswitch0 configured with:
load balancing: route based on IP Hash using
notity switch : yes
fallback: yes
active adapters: active/standby

However, two of the ESXi hosts are experiencing MAC flapping on the Cisco switches(standby NICs), where the MAC address of the active NIC is detected. The ESXi host with vCenter installed does not experience MAC flapping.

question2:
When the active NIC breaks down and recovers, the ESXi's network is disconnected for 30 seconds. Is this issue due to the configuration problem on the ESXi or the Cisco switches?"

How can this situation be explained and resolved?"

Re: ESXi 2NICs setting

BivasM — Tue, 18 Jul 2023 04:16:44 GMT

it is the expected behavior. if your adapters are on active/standby mode. cisco switches will only detect MAC of active adapters.

Re: ESXi 2NICs setting

olaq — Tue, 18 Jul 2023 05:32:32 GMT

Hi

Is MAC flapping on Cisco switches considered expected behavior?
How can it be avoided?
Should it be modified to active/active with ip hash or active/standby with port id ?

Re: ESXi 2NICs setting

BivasM — Tue, 18 Jul 2023 06:44:06 GMT

depends on what you want basically and what type of load balancing you are trying to design. if you want to use both nic then set to active/active. then cisco switches will discover both MAC.

Re: ESXi 2NICs setting

DeviVmware — Tue, 18 Jul 2023 07:27:22 GMT

@olaq Are you using Etherchannel on Cisco Switches ? IP Hash load balancing policy should be used only when Physical switches are configured in Etherchannel.

Deafult load balancing policy is Route based on Originating Virtual Port ID.

Re: ESXi 2NICs setting

olaq — Tue, 18 Jul 2023 09:05:00 GMT

I'm really puzzled because out of three ESXi hosts with the same configuration, one host doesn't experience MAC flapping regardless of being set to active/active or active/standby

Re: ESXi 2NICs setting

Kinnison — Tue, 18 Jul 2023 09:56:47 GMT

Hi,

@DeviVmwarehe's right, without "some form" of LAG configured on the physical switches using "IP hash" as a load balancing method, in practical terms, is of no use, certainly not with an active/standby policy. and @Bivas he's right as well given the case as presented.

Regards,
Ferdinando

Re: ESXi 2NICs setting

DeviVmware — Tue, 18 Jul 2023 11:44:34 GMT

@olaq i would recommend you to modify the load balancing policy. also, check your switch security policies.

Re: ESXi 2NICs setting

olaq — Wed, 19 Jul 2023 01:56:18 GMT

Hi @DeviVmware

I will follow your recommend
Thank you