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UCS VLAN Broadcast Listener Behavior


I have a couple of questions that I can't seem to find answers for regarding the per VLAN broadcast listeners for a disjoint layer 2 configuration.

1. When and how are the per VLAN broadcast listeners assigned?  If I have one uplink configured on an FI with existing VLANs (all listeners on this uplink) and I configure a second, separate uplink, will the broadcast listeners immediately redistribute for existing VLANs?  Or will they only distribute if the first uplink goes down? 
2. If I have 2 uplinks configured on an FI with no VLAN assignments in place but do have PIN groups for the vNICs (meaning the per VLAN broadcast listeners are distributed at random, but the server vNICs are properly pinned), and I do uplink assignments to VLANs for DJL2, will this cause any outage or require any reboots of the blades?  
2 Replies 2

Kirk J
Cisco Employee
Cisco Employee


The designated receiver role 'election/selection' you are referring to evaluates the number of server interfaces (Veths) pinned to it (fewer wins), and number of vlans it is already a designated receiver for (fewer wins).  Once a designated receiver is set, it will retain its role unless that specific link flaps or you remove the vlan from it.  Adding an additional link carrying the same vlan should not trigger a DR role change.

Still evaluating your 2nd question.



Chris K

If I understand your #2 question correctly; if you assign the VLANs to up-links in the "LAN Up-link Manager", will it be disruptive?

I performed this in recent times on 2.2(6e) without any kind of issue. Of course your environment is not mine so your mileage may vary. Mine was relatively idle during the change an had few vNICs and VLANs.

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