Posted on June 28, 2017 7:29 pm
 |  Asked by joe joe
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need to add multiple MS NLB addresses to switch, what is the best way do add multiples and what command entries?

Marked as spam
Posted by Heather Basquill
Answered on March 7, 2019 2:48 am

Not sure why this is marked as spam its a valid question

Do you have guidelines for this setup on the Arista platform? Please note I will start working on this bug was unable to find any documentation around the support on the Arista site.

Posted by Deepan Jayaraj
Answered on June 13, 2019 8:05 am

Hi Heather,

Microsoft NLB cluster works in 3 modes (Unicast, Multicast & IGMP mode). A special configurations are needed on our switches when it’s running in Multicast/IGMP mode – 01(3):00:5E:XX:YY:ZZ.

1) If the Microsoft NLB cluster is configured on those 2 modes, then it will send packets with Cluster IP (Unicast IP address) & Multicast MAC to the network. In general, switch/router in the network will not learn the Multicast MAC in the MAC address table.

2) Lets say, NLB cluster with IP & MAC 03:00:5E:XX:YY:ZZ is sending the packets to the GW (Ex:
2a) If the GW is present on Arista switch, then we have to configure Static ARP for this address: “arp 03:00:5E:XX:YY:ZZ arpa”

2b) If Arista is pure L2, then check if the IGMP snooping is active for that VLAN. If not active, then no need to configure anything on the switch which will flood the traffic to all the ports in the part of same VLAN. If IGMP snooping is active, then we have to add static IGMP snooping entry for uplink interface.

Hope this helps.

Please let us know if you need any other information. We will add the detail doc in our website "" sooner for NLB usage/configs in network infra.


Do we have a detail document on Website? I was unable to find one?
(Jignesh Davda at June 15, 2020 1:03 pm)
Posted by Deepan Jayaraj
Answered on March 24, 2021 4:07 pm

Please refer to the following EOS article link for more details on the NLB integration with Arista:

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