Possible STP issue

[Anonymous]

Hello guys,

How you doing!?

I'm writing you because I need a help with an issue that I'm very sure that is about STP, I'm attaching you an image that describes my topology, and the explanation is below:

I have two swtiches NV1234 that connects 4 servers in my data center, so today we set up two Traffic Balancers F5's, and them were connected to the switches in the way that is described on the diagram.

So both F5's can have 2 interfaces, the idea was connect the full mesh just like in the diagram, but the problem is that if I left connected the links that are marked in red, my network goes down.

I'm very sure that is because STP, but I want to consult this with you guys. I did a few configuration by setting the priority 0 to the switch that connects to the routers and set the pripority of the second SW to 10 I was thinking that the second switch would put some ports in blocking state but it didn't.

Would you help me here!?

Thanks a millions!

[Anonymous]

@dcorrea - Thanks for your question. We would be happy to help you out. We need further information to troubleshoot your issue. Could you provide the current configurations of both 1234s? Please be sure to edit out any information that would be sensitive to your company's network. Also, please specify which switchports on each 1234 are plugging into the following: 1.) load balancers 2.) the other 1234 3.) the internet routers Also, please provide the output to "show span" from both NetVanta 1234s while all connections are plugged in.

Let us know if you have any questions.

Thanks,

Noor

[Anonymous]

Dear Noor,

Thanks for the help on this topic, as you requested here are my both configurations of my switches.

PRIMARY

ip default-gateway 10.10.10.254

ip name-server 200.57.64.66 200.57.64.67

!

!

no auto-config

!

event-history on

no logging forwarding

no logging email

!

no service password-encryption

!

!

!

!

!

!

!

no dot11ap access-point-control

!

!

!

!

!

spanning-tree priority 0

!

!

!

vlan 1

  name "Default"

!

interface switchport 0/1

  no shutdown

!

interface switchport 0/2

  no shutdown

!

interface switchport 0/3

  no shutdown

!

interface switchport 0/4

  no shutdown

!

interface switchport 0/5

  no shutdown

!

interface switchport 0/6

  no shutdown

!

interface switchport 0/7

  no shutdown

!

interface switchport 0/8

  no shutdown

!

interface switchport 0/9

  no shutdown

!

interface switchport 0/10

  no shutdown

!

interface switchport 0/11

  no shutdown

!

interface switchport 0/12

  no shutdown

!

interface switchport 0/13

  no shutdown

!

interface switchport 0/14

  no shutdown

!

interface switchport 0/15

  no shutdown

!

interface switchport 0/16

  no shutdown

!      

interface switchport 0/17

  no shutdown

!

interface switchport 0/18

  no shutdown

!

interface switchport 0/19

  no shutdown

!

interface switchport 0/20

  no shutdown

!

interface switchport 0/21

  no shutdown

!

interface switchport 0/22

  no shutdown

!

interface switchport 0/23

  no shutdown

!

interface switchport 0/24

  no shutdown

!

!

interface gigabit-switchport 0/1

  no shutdown

!

interface gigabit-switchport 0/2

  no shutdown

!

interface gigabit-switchport 0/3

  no shutdown

!

interface gigabit-switchport 0/4

  no shutdown

  switchport mode trunk

!

!

!

interface vlan 1

  ip address  10.10.10.251  255.255.255.0

  no shutdown

!

!

!      

no tftp server

no tftp server overwrite

ip http server

ip http secure-server

no ip snmp agent

no ip ftp server

ip ftp server default-filesystem flash

no ip scp server

no ip sntp server

!

!

!

!

!

!

!

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

SH SPAN ON MAIN SWITCH

NV1234-LAN-SW#sh span

STP 0

Vlan 1

  Spanning Tree enabled protocol ieee 802.1w (Rapid Spanning-Tree)

  Root ID    Priority     0

             Address      00:a0:c8:77:a3:22

             The root of the spanning tree

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

  Bridge ID  Priority     0

             Address      00:a0:c8:77:a3:22

             Aging Time   300

Interface        Role Sts Cost      Prio.Nbr Type

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

swx 0/1          Desg FWD 19         128.1   P2p  

swx 0/2          Desg FWD 19         128.2   P2p  

swx 0/3          Desg FWD 19         128.3   P2p  

swx 0/4          Desg FWD 19         128.4   P2p  

swx 0/5          Desg FWD 19         128.5   P2p  

swx 0/7          Desg FWD 19         128.7   P2p  

swx 0/9          Desg FWD 19         128.9   P2p  

swx 0/11         Desg FWD 19         128.11  P2p  

swx 0/13         Desg FWD 19         128.13  P2p  

swx 0/14         Desg FWD 19         128.14  P2p  

swx 0/23         Desg FWD 19         128.23  P2p  

swx 0/24         Desg FWD 19         128.24  P2p  

giga-swx 0/3     Desg FWD 4          128.27  P2p  

giga-swx 0/4     Desg FWD 4          128.28  P2p  

SECONDARY SWITCH

!

! ADTRAN, Inc. OS version 18.01.04.00

! Boot ROM version 17.03.02.SB

! Platform: NetVanta 1234, part number 1700594G1

! Serial number LBADTN1116AC560

!

!

hostname "NV1234-LAN-SW2"

enable password password

!

clock timezone -6-Mexico-City

ip default-gateway 10.10.10.254

ip name-server 200.57.64.66 200.57.64.67

!

!

no auto-config

!

event-history on

no logging forwarding

no logging email

!

no service password-encryption

!

!

!

!

!

!

!

no dot11ap access-point-control

!

!

!

!

!

spanning-tree priority 2

!

!

!

vlan 1

  name "Default"

!

interface switchport 0/1

  no shutdown

!

interface switchport 0/2

  no shutdown

!

interface switchport 0/3

  no shutdown

!

interface switchport 0/4

  no shutdown

!

interface switchport 0/5

  no shutdown

!

interface switchport 0/6

  no shutdown

!

interface switchport 0/7

  no shutdown

!

interface switchport 0/8

  no shutdown

!

interface switchport 0/9

  no shutdown

!

interface switchport 0/10

  no shutdown

!

interface switchport 0/11

  no shutdown

!

interface switchport 0/12

  no shutdown

!

interface switchport 0/13

  no shutdown

!

interface switchport 0/14

  no shutdown

!

interface switchport 0/15

  no shutdown

!

interface switchport 0/16

  no shutdown

!      

interface switchport 0/17

  no shutdown

!

interface switchport 0/18

  no shutdown

!

interface switchport 0/19

  no shutdown

!

interface switchport 0/20

  no shutdown

!

interface switchport 0/21

  no shutdown

!

interface switchport 0/22

  no shutdown

!

interface switchport 0/23

  no shutdown

!

interface switchport 0/24

  no shutdown

!

!

interface gigabit-switchport 0/1

  no shutdown

!

interface gigabit-switchport 0/2

  no shutdown

!

interface gigabit-switchport 0/3

  no shutdown

!

interface gigabit-switchport 0/4

  no shutdown

  switchport mode trunk

!

!

!

interface vlan 1

  ip address  10.10.10.250  255.255.255.0

  no shutdown

!

!

!      

no tftp server

no tftp server overwrite

ip http server

ip http secure-server

ip snmp agent

no ip ftp server

ip ftp server default-filesystem flash

no ip scp server

no ip sntp server

!

!

!

!

!

snmp-server enable traps

snmp-server community public RO

snmp-server community private RW

snmp-server host 10.10.10.120 traps version 2c public

!

!

!

!

line con 0

  no login

!

line telnet 0 4

  login

  password password

  no shutdown

line ssh 0 4

  login local-userlist

  no shutdown

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

SECONDARY SWITCH SH SPAN

NV1234-LAN-SW2#sh spanning-tree

STP 0

Vlan 1

  Spanning Tree enabled protocol ieee 802.1w (Rapid Spanning-Tree)

  Root ID    Priority     0

             Address      00:a0:c8:77:a3:22

             Cost         4

             Port         25 (giga-swx 0/1)

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

  Bridge ID  Priority     2

             Address      00:a0:c8:77:9a:fa

             Aging Time   300

Interface        Role Sts Cost      Prio.Nbr Type

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

swx 0/1          Desg FWD 19         128.1   P2p  

swx 0/3          Desg FWD 19         128.3   P2p  

swx 0/4          Desg FWD 19         128.4   P2p  

swx 0/5          Desg FWD 19         128.5   P2p  

swx 0/7          Desg FWD 19         128.7   P2p  

giga-swx 0/1     Root FWD 4          128.25  P2p 

Now talking about the connections, here is the map:

1) The loadbalancers are connected to each switch on gigabit switchport G0/1 and G0/2

2)The trunk link of the switches is located on port G0/3

3)The routers are connected on the main switch (NV1234-LAN-SW) on ports swx0/23 and swx 0/24

Hope this information helps you on this issue.

Thanks a millions!

[Anonymous]

@dcorrea - Thank you for providing that information. I noticed a couple of things based on the "show span" outputs you provided from both switches"

- First, the "show span" output is showing inconsistencies based on how you stated everything is connected:

• Load balancers are connected to each switch on G0/1 and G0/2.
  • I am only seeing G0/3 and G0/4 active on the primary 1234
  • Also, I am only seeing G0/1 active on the secondary 1234
• Trunk link of the switches is on G0/3
  • I am seeing that only G0/4 of both the primary and secondary switches are in trunk mode.
  • Also, as I mentioned above, G0/3 and G0/4 are only active on the primary 1234 and not the secondary 1234

At the point where you obtained the "show span" output, there were currently no detected loops in your network. Therefore all ports on the primary and secondary 1234 were in a forwarding state. Based on the diagram you sent, the design is a legitimate one, however, we need to see the output of "show span" with all connections active to see what spanning-tree is calculating. We also need to confirm which switchports on both the primary and secondary 1234s are plugging into which equipment. Also, is there a direct link between the Load Balancers in the network?

Let us know if you have any questions.

Thanks,

Noor

[Anonymous]

Dear Noor,

Thanks for the follow up on this, you were right in your assumptions, the situation is that because a failure that we have with the loop, they disconnect the load balancers , and also yes the switches have the trunk on the g0/4.

So the point is to try to replicate the scenario that is described on my image, but I need to do this next weekend.

So, it is possible for you to give me some suggestions in how configure the switches in order to avoid the loop on the network if i set up the load balancers again!?

Thanks in advance,

[Anonymous · Accepted solution]

@dcorrea - I think you were correct in setting the primary switch with a spanning-tree priority of 0 and the secondary switch with a higher priority. I don't see a reason why the switches wouldn't have been able to detect the loops, so I suspect that the load balancers may be involved in some way. This is part of the reason I would like to see an accurate topology with the ports labeled and the output of "show span" with everything plugged in.

Please reply to this post with that information once you have a chance to set it up.

Thanks,

Noor

[Anonymous]

Dear Noor,

Thanks for the feedback, I will ask the customer if they F5 balancers can handle the spanning tree and after that maybe this weekend I will work on it.

I'll collect the information about connected ports and status of the spanning tree for future troubleshooting.

Thanks a bunch!

[Anonymous]

@dcorrea - I went ahead and marked this post as "assumed answered".  Feel free to mark any correct or helpful answers from this post.  If you still need assistance with this issue I would be more than happy to help, just let me know in a reply.

Thanks,

Noor

[Anonymous]

:

I went ahead and flagged the "Correct Answer" on this post to make it more visible and help other members of the community find solutions more easily. If you don't feel like the answer I marked was correct, feel free to come back to this post and unmark it and select another in its place with the applicable buttons.  If you still need assistance, we would be more than happy to continue working with you on this - just let us know in a reply.

Thanks,

Levi