05-24-2018 05:50 PM - edited 03-08-2019 03:08 PM
hi guys
i have a strange problem
i have two cisco 3850 stack switches and add all vlans on it
when i use "show spanning-tree summary" command, just 128 vlan shown
and when i use "sho run | s vlan" displays:
no spanning-tree vlan 1138-1243,1245-1467,1470-1533,1555-1563,1565-1576,1580
no spanning-tree vlan 1581-1582,1585,1589-1590,1592,1630-1635,1800,1900,2001
no spanning-tree vlan 2003,2010,2100,2228,2504,2526,2550,2610,2624,2650-2653
no spanning-tree vlan 2660,2700-2709,2720-2724,2726-2727,2790,2800-2802,2804
no spanning-tree vlan 2820-2825,4000,4092
BTW, this vlans doesnt work correctly and i cannot correct them
is there anybody can help me?
regards
Reza
Solved! Go to Solution.
05-25-2018 04:11 AM
Hi
Those times I run into this issue I used the "switchport trunk allowed vlan <>" on the core switch to remove unnecessary vlans. Also I used vtp transparent on the edge switches so they will not learn of vlans not needed, and then only activate the vlans that are needed. That way I only had to use those vlans that actually are needed on the edge switches. Be aware of the limitation that is different on different hardware.
If you miss this there is a risk for loops in the network if spanning-tree is not running for a vlan.
/Mikael
05-24-2018 08:46 PM
Hi Reza,
Can you post the output of "sh run" and "sh vlan" from the switch stack?
Reza
05-25-2018 02:09 AM
05-25-2018 02:45 AM
its another thing i see
i deleted all vlan
and define again, after adding more and more, "no spanning-tree vlan ...." appear in show run
i told this maybe help
regards
Reza
05-25-2018 12:07 AM
Hi
128 is the limitation of spanning-tree instances, see this link
/Mikael
05-25-2018 02:13 AM
05-25-2018 04:11 AM
Hi
Those times I run into this issue I used the "switchport trunk allowed vlan <>" on the core switch to remove unnecessary vlans. Also I used vtp transparent on the edge switches so they will not learn of vlans not needed, and then only activate the vlans that are needed. That way I only had to use those vlans that actually are needed on the edge switches. Be aware of the limitation that is different on different hardware.
If you miss this there is a risk for loops in the network if spanning-tree is not running for a vlan.
/Mikael
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