The same vlan ID between two different MST regions name

[Roberto Borges]

Hi, 

We currently have a two core switches connected each other on between different data centers in order to allow the comunication. I have found a issue with spanning tree for specific vlan id that should be shared between them . So in case the spanning tree status for uplink port has the mstr condition due to MST different region name was configured on these switches . So I want to fix this behavior for spefic vlan id but without change MST region names between them. I would be appreciate any help.

Thanks,

[Sergiu.Daniluk]

Hi @Roberto Borges 

What do you mean Mstr condition? Mstr (Master port) is the uplink port of CIST Root. I am not quite sure what you say as being the problem. Can you give more details regarding what you say the problem is and what you want to achieve? Feel free to add show outputs from the switches if they are relevant to describing what you say is the problem.

Regards,

Sergiu

[Roberto Borges]

Hi @Sergiu.Daniluk 

 I mean the boundary port between another switch is showing "Mstr status " when I type the command "show spann vlan 401" as you can see  in the output below. So based on this I read the documentation and my findings were it that means  the  incompatible between switches and in order to handle this behavior I  should to apply the command "spanning-tree mst pre-standard"  under the interface  to force it, but before move forward with this solution I would like to check it. 

Switch  # sh spanning-tree vlan 401

MST0001

  Spanning tree enabled protocol mstp

  Root ID    Priority    1

             Address     00de.fb2c.c4bc

             This bridge is the root

             Hello Time  2  sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    1      (priority 0 sys-id-ext 1)

             Address     00de.fb2c.c4bc

             Hello Time  2  sec  Max Age 20 sec  Forward Delay 15 sec

Interface        Role Sts Cost      Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Po301            Desg FWD 200       128.4396 (vPC) P2p

Po302            Desg FWD 200       128.4397 (vPC) P2p

Po4090           Desg FWD 250       128.8185 (vPC peer-link) Network P2p

Eth8/10          Desg FWD 20000     128.1034 P2p

Eth8/19          Mstr FWD 20000     128.1043 P2p Bound(RSTP)

Regards,

Roberto 

[Sergiu.Daniluk]

Hi @Roberto Borges 

The output is expected in a multi-region MST environment. It's just the uplink port of CIST Root. As always, the graphics helps, so I found this diagram:

Reference: https://forum.huawei.com/enterprise/en/all-about-switches-example-for-configuring-mstp/thread/213021-861 

Do you see forwarding issues/instability/loops/network hiccups in your environment?If yes, then without a doubt, further investigation must be done ^_^

Best regards,

Sergiu

[Roberto Borges]

Hi @Sergiu.Daniluk 

I am facing connectivity issue with servers is belong to vlan 401 that is shared between 2 MST region names different. So I am looking for any way to fix it. So that ´s why I am working this behavior. 

Regards, 

Roberto 

[Sergiu.Daniluk]

Hello,

Can you answer the following questions:

1. What do you mean by connectivity problem?  is it all IP traffic affected or only TCP or UDP?

2. How does the problem manifests:

+ connectivity between servers is not working at all

+ connectivity is dropping sporadically

+ connectivity is dropping repeatedly/periodically

3. Are all servers from DC A experiencing the connectivity issue while trying to ping all servers from DC B?

4. Are servers from DC A experiencing the connectivity problem if they try to ping other servers from DC A?

5. Are servers from DC B experiencing the connectivity problem if they try to ping other servers from DC B?

6. Are servers from any other vlan part of MST1 affected?

Cheers,

Sergiu

[Roberto Borges]

Hello, 

Please see my answers below for your questions.

Can you answer the following questions:

1. What do you mean by connectivity problem? is it all IP traffic affected or only TCP or UDP?

I mean the servers on this vlan 401 cannot talk with servers on the same vlan through this uplink.

2. How does the problem manifests:

+ connectivity between servers is not working at all
Yes these servers are not ping each other even though just vlan only layer 2

+ connectivity is dropping sporadically
The communication not worked before
+ connectivity is dropping repeatedly/periodically
In case I want to allow this vlan 401 through this new uplink
3. Are all servers from DC A experiencing the connectivity issue while trying to ping all servers from DC B?
I am facing issues only this vlan 401 for another vlans are not being affected,however it only this vlan is working on layer 2
4. Are servers from DC A experiencing the connectivity problem if they try to ping other servers from DC A?
I am not facing issues for other servers. So I am facing issues when the server on the vlan 401 from DC A are trying to talk with another server on the vlan 401 from DC B
5. Are servers from DC B experiencing the connectivity problem if they try to ping other servers from DC B?
I don´t have any issue for servers on the same DataCenter,the issue only happens when I need to talk with servers on the vlan 401 from another DC A
6. Are servers from any other vlan part of MST1 affected?
No I noticed that behavior only affected servers on the vlan 401.

I hope I have clarified your doubts if not please feel free for ask another questions regarding it. 

Regards, 

Roberto 

[Sergiu.Daniluk]

Hi @Roberto Borges 

Based on your feedback, it seems that the STP is not the problem here, since other VLANs in MST1 are not affected.

I would suggest to verify that the vlan is configured and allowed in MST1 on all switches in both MST regions. Also, as a testing step, verify if MAC addresses from one DC are learned in the other DC for VLAN 401.

Regards,

Sergiu

[paul driver]

Hello

---

@Roberto Borges wrote:

Eth8/19          Mstr FWD 20000     128.1043 P2p Bound(RSTP)

---

The is the stp root for mst1 and this master port is the boundary the port towards the cist root.

post the output for
show spanining-tree MST 0
show spanining-tree MST 1

[Roberto Borges]

HI @paul driver , 

Please see the output below 

show spanning-tree MST 0

##### MST0 vlans mapped: none
Bridge address 00de.fb2c.c4bc priority 32768 (32768 sysid 0)
Root address 0023.04ee.be0a priority 32768 (32768 sysid 0)
port Eth8/19 path cost 20000
Regional Root this switch
Operational hello time 2 , forward delay 15, max age 20, txholdcount 6
Configured hello time 2 , forward delay 15, max age 20, max hops 20

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po301 Desg FWD 200 128.4396 (vPC) P2p
Po302 Desg FWD 200 128.4397 (vPC) P2p
Po4090 Desg FWD 250 128.8185 (vPC peer-link) Network P2p
Eth8/10 Desg FWD 20000 128.1034 P2p
Eth8/19 Root FWD 20000 128.1043 P2p Bound(RSTP)

show spanning-tree MST 1

##### MST1 vlans mapped: 1-4094
Bridge address 00de.fb2c.c4bc priority 1 (0 sysid 1)
Root this switch for MST1

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po301 Desg FWD 200 128.4396 (vPC) P2p
Po302 Desg FWD 200 128.4397 (vPC) P2p
Po4090 Desg FWD 250 128.8185 (vPC peer-link) Network P2p
Eth8/10 Desg FWD 20000 128.1034 P2p
Eth8/19 Mstr FWD 20000 128.1043 P2p Bound(RSTP)

Regards, 

Roberto

[Roberto Borges]

Hi @Sergiu.Daniluk, 

Thanks for attention on this case. 

[Sergiu.Daniluk]

No problem. Once again, this does not look like a MST issue. You should look at other things as configuration, physical connectivity, server configuration, mac/ip learning etc.

Stay safe!

Sergiu

[paul driver]

Hello
Can you post a topology diagram of your network and then if possible the stp mst running config and readout of both those switches 
sh spanning-tree mst configuration
sh spanning-tree mst x

[Roberto Borges]

Hello @paul driver 

Please see the output below from both sides and also I attached the topology of this environment in order to illustrate the scenario.

DC A

sh spanning-tree mst configuration
Name [DATACENTERA]
Revision 1 Instances configured 2

Instance Vlans mapped
-------- ---------------------------------------------------------------------
0 none
1 1-4094
-------------------------------------------------------------------------------
sh spanning-tree mst 1

##### MST1 vlans mapped: 1-4094
Bridge address 00de.fb2c.c4bc priority 1 (0 sysid 1)
Root this switch for MST1

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po301 Desg FWD 200 128.4396 (vPC) P2p
Po302 Desg FWD 200 128.4397 (vPC) P2p
Po4090 Desg FWD 250 128.8185 (vPC peer-link) Network P2p
Eth8/10 Desg FWD 20000 128.1034 P2p
Eth8/19 Mstr FWD 20000 128.1043 P2p Bound(RSTP)

sh spanning-tree mst 0

##### MST0 vlans mapped: none
Bridge address 00de.fb2c.c4bc priority 32768 (32768 sysid 0)
Root address 0023.04ee.be0a priority 32768 (32768 sysid 0)
port Eth8/19 path cost 20000
Regional Root this switch
Operational hello time 2 , forward delay 15, max age 20, txholdcount 6
Configured hello time 2 , forward delay 15, max age 20, max hops 20

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po301 Desg FWD 200 128.4396 (vPC) P2p
Po302 Desg FWD 200 128.4397 (vPC) P2p
Po4090 Desg FWD 250 128.8185 (vPC peer-link) Network P2p
Eth8/10 Desg FWD 20000 128.1034 P2p
Eth8/19 Root FWD 20000 128.1043 P2p Bound(RSTP)

DC B

sh spanning-tree mst configuration
Name [DATACENTERB]
Revision 1 Instances configured 2
Instance Vlans mapped
-------- ---------------------------------------------------------------------
0 none
1 1-4094
-------------------------------------------------------------------------------
sh spanning-tree mst 0

##### MST0 vlans mapped: none
Bridge address 0023.04ee.be0a priority 32768 (32768 sysid 0)
Root this switch for the CIST
Regional Root this switch
Operational hello time 2 , forward delay 15, max age 20, txholdcount 6
Configured hello time 2 , forward delay 15, max age 20, max hops 20

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po101 Desg FWD 200 128.4196 (vPC) P2p
Po4090 Desg FWD 250 128.8185 (vPC peer-link) Network P2p
Eth8/1 Desg FWD 2000 128.1025 P2p
Eth8/3 Desg FWD 20000 128.1027 P2p
Eth8/8 Desg FWD 20000 128.1032 P2p
Eth8/10 Desg FWD 20000 128.1034 P2p

sh spanning-tree mst 1

##### MST1 vlans mapped: 1-4094
Bridge address 0023.04ee.be0a priority 1 (0 sysid 1)
Root this switch for MST1

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po101 Desg FWD 200 128.4196 (vPC) P2p
Po4090 Desg FWD 250 128.8185 (vPC peer-link) Network P2p
Eth8/1 Desg FWD 2000 128.1025 P2p
Eth8/3 Desg FWD 20000 128.1027 P2p
Eth8/8 Desg FWD 20000 128.1032 P2p
Eth8/10 Desg FWD 20000 128.1034 P2p

Regards, 

Roberto 

[paul driver]

Hello
According to that stp readout it looks like you have the topology diagram incorrect.
Shouldn’t it be this:
DCA show port 8/19  - DATACENTERA
DCA show port 8/3   -  DATACENTERB

From what i can see is DCA/DCA B have the same regional MSTI 1 priorities but DC A has a higher port id for the CIST (IST) root so DCB is the CST root.

DC B
Bridge address 0023.04ee.be0a priority 32768 (32768 sysid 0)
Root this switch for the CIST

DC B Eth8/3 Desg FWD 20000 128.1027 = MST0 
DC B Eth8/3 Desg FWD 20000 128.1027 = MST1

DC A
Eth8/19 Root FWD 20000 128.1043  = MST0
Eth8/19 Mstr FWD 20000 128.1043 P2p Bound(RSTP  = MST 1

Hence why on DC A for both mst 0/1 you see 8/19 as a boundary root port with vlan 1 and other vlans stating its a boundary master port, which means it’s the port towards the CIST root switch

Suggest then you could make either of the stp region the to have the better preferred MST priority for both mst 0-1 instances and negate manually prunning vlans from trunks which isnt recommended in MSTP.