05-05-2010 05:31 AM - edited 03-06-2019 10:56 AM
Hi there,
I have 4 3560 connected to core 3750 with 2gb portchannel.
I do have 244 VLANs on my network and from what i know you can only have 128 on spanning tree instance.
After running show spanning-tree command i can se that only half of my vlans are listed.
Is this means on the other half i will have a broadcast storms and other wierd stuff ?
How can i spann for all the vlans ?
Kind regards
marcin
05-05-2010 05:42 AM
are all your vlans listed in the vlan database as active?. do "show vlan brief"
If there is no port forwarding traffic in a vlan, stp instance will not be created for that vlan.
05-05-2010 05:45 AM
Yes, all my vlans are listed as active.
05-05-2010 05:50 AM
like i said if there is no active port forwarding in a vlan, then no stp instance for that vlan when you look at stp info on the switch you will only see stp info for vlans with active port forwarding traffic.
Also you can have a max 128 instance, you have more vlans that max instance on the switch. do you need all vlans?
05-05-2010 06:03 AM
marcin.piesio wrote:
Yes, all my vlans are listed as active.
Marcin
Unless you are daisy chaining switches where a vlan is needed on a remote switch so you have to include it on the intermediate switch or unless you are running trunks on all ports with devices that need access to all 244 vlans then i can't see why each switch needs to have all 244 vlans active. Like i said with 48 ports per switch how can you need 244 vlans per switch.
Jon
05-05-2010 07:40 AM
3560 ports are trunk connected to coax ip switches which are connected to 12 devices.
Every device have to be on seperate vlan. We will have 20 of of those coax switches = 21*12=252 and we will "only" use 244.
So not all the switches need access to all 244 vlans, but this eventually connects to the core which should be a root bridge for all vlans and it cannot because of 128 limitation.
Is my MSTP design below makes sense ?
From what i understand you specify region for a pool of vlans ?
05-05-2010 05:45 AM
marcin.piesio wrote:
Hi there,
I have 4 3560 connected to core 3750 with 2gb portchannel.
I do have 244 VLANs on my network and from what i know you can only have 128 on spanning tree instance.
After running show spanning-tree command i can se that only half of my vlans are listed.
Is this means on the other half i will have a broadcast storms and other wierd stuff ?
How can i spann for all the vlans ?
Kind regards
marcin
Marcin
You would have to make sure there is no loop for any vlan that does not have an STP instance running.
If you have more than 128 STP instances then you need to either -
1) look if your switch actually needs all 244 vlans. Considering there are only 48 ports on each switch then it is unlikely you need all 244 vlans on each switch. If you clear the vlan off any trunk links to a switch, assuming the switch does not have any ports in that vlan, then STP will not run on a vlan for a switch that has no active ports in that vlan.
2) alternatively you could look at implementing MSTP which allows yhou to groups vlans together and only run one STP instance for each grroup -
Jon
05-05-2010 05:51 AM
According to Jon's suggestion, you might have to use MSTP.
Francisco.
05-05-2010 06:03 AM
Dont ask me why but yes we need all 244.
There are no loops on the network, my only concern is that port channel is already redundant link so the question is now can portchannel creating switching loops ?
thanks for your quick response
Marcin
05-05-2010 06:34 AM
marcin.piesio wrote:
Dont ask me why but yes we need all 244.
There are no loops on the network, my only concern is that port channel is already redundant link so the question is now can portchannel creating switching loops ?
thanks for your quick response
Marcin
Marcin
If you really do need all 244 vlans on each switch and i can;t see why you would then i would suggest looking at MSTP as per previous thread so that you can run STP on all vlans.
Portchannel could in theory create a loop, that is why STP should be run on all vlans. It is your L2 failsafe.
Jon
05-05-2010 07:47 AM
3560 ports are trunk connected to coax ip switches which are connected to 12 devices.
Every device have to be on seperate vlan. We will have 20 of of those coax switches = 21*12=252 and we will "only" use 244.
So not all the switches need access to all 244 vlans, but this eventually connects to the core which should be a root bridge for all vlans and it cannot because of 128 limitation.
Is my MSTP design below makes sense ?
From what i understand you specify region for a pool of vlans ?
05-05-2010 08:11 AM
This URL discusses some MSTP design-related questions http://blog.ine.com/2010/02/22/understanding-mstp/
05-13-2010 02:31 AM
Hi there,
can some please help me with my mst config:
sw1(running rapid-pvst) directly connected to sw2(running mst)
sw1 is root for vlans range 1-100 (about 30 vlans in range)
sw2 is root for vlans 101-350
sw2
mst config
instance 0 vlan 7,19,88,101-350
instance 1 vlan 1-6,8-18,20-87,89-4094
trunk between sw1 and sw2 config
switchport trunk encapsulation dot1q
switchport mode trunk
when enabling trunk i receive msg
%SPANTREE-2-PVSTSIM_FAIL: Blocking root port Gi0/24: Inconsitent inferior PVST BPDU received on VLAN 4, claiming root 24580:0022.55bb.1500
and sh spann output
sh spanning-tree
MST0
Spanning tree enabled protocol mstp
Root ID Priority 24577
Address 0022.55bb.1500
Cost 20008
Port 24 (GigabitEthernet0/24)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32768 (priority 32768 sys-id-ext 0)
Address ec44.7643.4980
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi0/24 Root BKN*20000 128.24 P2p Bound(PVST) *PVST_Inc
MST2
Spanning tree enabled protocol mstp
Root ID Priority 32770
Address ec44.7643.4980
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32770 (priority 32768 sys-id-ext 2)
Address ec44.7643.4980
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi0/24 Mstr BKN*20000 128.24 P2p Bound(PVST) *PVST_Inc
when i unplug and plug the cable again it doesn't block the link and it works. sh spann output below
sh spanning-tree
MST0
Spanning tree enabled protocol mstp
Root ID Priority 24577
Address 0022.55bb.1500
Cost 20008
Port 24 (GigabitEthernet0/24)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32768 (priority 32768 sys-id-ext 0)
Address ec44.7643.4980
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi0/24 Root FWD 20000 128.24 P2p Bound(PVST) *PVST_Inc
MST2
Spanning tree enabled protocol mstp
Root ID Priority 32770
Address ec44.7643.4980
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32770 (priority 32768 sys-id-ext 2)
Address ec44.7643.4980
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi0/24 Mstr BKN*20000 128.24 P2p Bound(PVST) *PVST_Inc
can you please explain why does it fail on first attempt ?
i want to limit my trunk to vlan only vlans 7,19 and 88 by applying below config
switchport trunk allowed vlan 7,19,88 when enable link mst blocks it.
is there anything i am missing in my config to make it work ?
thanks for your response
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