both Core Switches are Master for vlan 10 on N3024F core switches

 switch1 (servers1) and switch2 (servers2) are both connected to the two core switches via there uplinks. the both server switches are on vlan server 10.they are not connected to each other only connected to the Cores.

after the problem happened i removed the second switch i added and kept the first switch only the both cores was showing master for vlan 10. :

the interfaces connected to the core all trunk on core and on edge uplinks because i have two vlans on each edge switch server vlan and managment vlan.

what could be the problem..?

Core1#show vrrp

Admin Mode..................................... Enable
Router Checksum Errors......................... 0
Router Version Errors.......................... 0
Router VRID Errors............................. 0
Vlan 10 - Group 10
Primary IP Address............................. 10.10.10.1
VMAC Address................................... 0000.5E00.010A
Authentication Type............................ None
Priority....................................... 200
Configured Priority............................ 200
Advertisement Interval (secs).................. 1
Accept Mode.................................... Enable
Pre-empt Mode.................................. Enable
Pre-empt delay................................. 0
Administrative Mode............................ Enable
State.......................................... Master
Timers Learn mode.............................. Disable
Description....................................
No interfaces are tracked for this vrid and interface combination
No routes are tracked for this vrid and interface combination

Core2#show vrrp

Admin Mode..................................... Enable
Router Checksum Errors......................... 0
Router Version Errors.......................... 0
Router VRID Errors............................. 0
Vlan 10 - Group 10
Primary IP Address............................. 10.10.10.1
VMAC Address................................... 0000.5E00.010A
Authentication Type............................ None
Priority....................................... 100
Configured Priority............................ 100
Advertisement Interval (secs).................. 1
Accept Mode.................................... Enable
Pre-empt Mode.................................. Disable
Pre-empt delay................................. 0
Administrative Mode............................ Enable
State.......................................... Master
Timers Learn mode.............................. Disable
Description....................................
No interfaces are tracked for this vrid and interface combination
No routes are tracked for this vrid and interface combination

tried to decrease core 2 priority to 195 and enable preempt also same issue both are master

on each edge switch i am using two vlans: vlan for users and the other management the interface that two interfaces that is going to core switches master and backup are trunked also the interfaces on the cores are trunked and the connectivity is fine and everything is reachable also the redundancy is working well when disconnecting one of the interfaces..but i think its not the ideal or best scinario to have the both are master?? i really serached much and reconfigured from the scratch and tried everything just one vlan that is working fine master and backup but any new vlan i add directly it goes to master master?

i think with if i unplug the interface from the backup switch and put it in the master this will make loop ???

what is the idea about??

any update please

update on the issue.

problem solved with changing the spanning tree protocol from RSTP to PVST, with RSTP the uplinks to the core switch were blocked by RSTP which makes the VRRP not working properly and stay in master master mode.

so the solution in this case is to make fine tunning to RSTP which i don't recommend or to change to PVST. which solved all the issues.

finally i just wanna make sure of one thing daniel,

on both uplinks from any edge switch to the both cores (core 1 and core 2)

on the active uplink when i do the command show mac address-table interface tengigabitethernet 1/0/1 >> the result that it has mac addresses 

but on the passive uplink which goes to core 2 (backup) it show no mac addresses.

which i believe it should show 1 or 2 Mac addreses same as  the other edge switches.

i tried to shut the link and no shut but with no luck it still shows no macc address on it.

no, 

now all edges are running the PVST and the core 1 are Primarry for All vlans and core two secondary for all vlans this is from PVST side...

From VRRP side Core 1 is active for all vlans and core two is backup for all vlans...all VRRP settings are correct for all vlans core 1 is active and core 2 is backup,, but when issuing the show mac addres-table interface tengigabitethernet 1/0/1(that going to core 1) on the uplinks of edges  has the mac address but ten1/0/2(that going to core 2) has no mac addresses, the other edge switches are working perfect the uplink to core 1 has all the mac addreses and the uplink to core 2 has 1 or two addresses.

the issue only on some switches. that has the same config of the other switches(edge) 

thank you Daniel,

its working fine until now :) with the PVST spanning tree instead of using MLAG Domain because the MLAG partners(Access switches) are more than 8 so we cannot make MLAG.

the problem now that i am now running new deployment with Single tier MLAG on two DELL N3000 Core switches and 4 Edge (access switches that running Vlan 15 and 200 for MAnagemnt)

MLAG configuration is running perfect no problems with disabling the spanning tree on Peer link and enabling UDLD.

the vrrp also configured on the same core switches.. i have 5 vlans (200,210,205,205,215)

vlan 215 and 206 is for servers and clients and are configured on the cores witches in access mode.

vlan 200 is for managment the switches and vlan 215 is for the three other switches that connected to the cores via PO 100,1001,102 VPC 55 , 56 ,57

the MLAG output is running perfect.

but the vrrp on the vlans (215,200) that connected to the three switches is still in the master master mode and the vlans that connected in access mode on the core switches is in active backup mode.

the question is should i disable the spanning tree protocol on the uplinks Port channels that is connected to the three switches ?? so i get there vlans in Active backup mode.????