STP topology changes
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‎08-10-2017 03:20 PM
I've been trying to track down an issue with STP in one of our branch offices, for some reason STP has an immense amount of STP changes logged;
i.e
Topology Change Detected: FALSE Topology Change: FALSE
Number of Topology Changes: 4974700
Time Since Last Topology Change: 42s
It's worth to note that we have a mixed environment with HP's and EXTREME's, does this config look correct ?
Stpd: s1 Stp: ENABLED Number of Ports: 46
Rapid Root Failover: Disabled
Operational Mode: 802.1W Default Binding Mode: EMISTP
802.1Q Tag: (none)
Ports: 1:1*,1:3,1:4,1:5,1:6,1:7,1:8,1:9,1:10,1:11,
1:12,1:13,1:14,1:15,1:16,1:17,1:18,1:19,1:20,1:21,
1:22,1:23,1:24,2:1*,2:3,2:4,2:5,2:6,2:7,2:8,
2:9,2:10,2:11,2:12,2:13,2:14,2:15,2:16,2:17,2:18,
2:19,2:20,2:21,2:22,2:23,2:24
Participating Vlans: Default
Auto-bind Vlans: Default
Bridge Priority: 28672
BridgeID: 70:00:02:04:96:51:b9:fd
Designated root: 70:00:02:04:96:51:b9:fd
RootPathCost: 0 Root Port: ----
MaxAge: 20s HelloTime: 2s ForwardDelay: 15s
CfgBrMaxAge: 20s CfgBrHelloTime: 2s CfgBrForwardDelay: 15s
Topology Change Time: 35s Hold time: 1s
Topology Change Detected: FALSE Topology Change: FALSE
Number of Topology Changes: 4974700
Time Since Last Topology Change: 192s
ON AN HP:
HP-2848-LA-CAR-R8-1# show spanning-tree
Rapid Spanning Tree (RSTP) Information
STP Enabled : Yes
Force Version : RSTP-operation
Switch Priority : 32768 Hello Time : 2
Max Age : 20 Forward Delay : 15
Topology Change Count : 405,614
Time Since Last Change : 4 mins
Root MAC Address : 020496-51b9fd
Root Path Cost : 22000
Root Port : 43
Root Priority : 28672
Any ideas?
i.e
Topology Change Detected: FALSE Topology Change: FALSE
Number of Topology Changes: 4974700
Time Since Last Topology Change: 42s
It's worth to note that we have a mixed environment with HP's and EXTREME's, does this config look correct ?
Stpd: s1 Stp: ENABLED Number of Ports: 46
Rapid Root Failover: Disabled
Operational Mode: 802.1W Default Binding Mode: EMISTP
802.1Q Tag: (none)
Ports: 1:1*,1:3,1:4,1:5,1:6,1:7,1:8,1:9,1:10,1:11,
1:12,1:13,1:14,1:15,1:16,1:17,1:18,1:19,1:20,1:21,
1:22,1:23,1:24,2:1*,2:3,2:4,2:5,2:6,2:7,2:8,
2:9,2:10,2:11,2:12,2:13,2:14,2:15,2:16,2:17,2:18,
2:19,2:20,2:21,2:22,2:23,2:24
Participating Vlans: Default
Auto-bind Vlans: Default
Bridge Priority: 28672
BridgeID: 70:00:02:04:96:51:b9:fd
Designated root: 70:00:02:04:96:51:b9:fd
RootPathCost: 0 Root Port: ----
MaxAge: 20s HelloTime: 2s ForwardDelay: 15s
CfgBrMaxAge: 20s CfgBrHelloTime: 2s CfgBrForwardDelay: 15s
Topology Change Time: 35s Hold time: 1s
Topology Change Detected: FALSE Topology Change: FALSE
Number of Topology Changes: 4974700
Time Since Last Topology Change: 192s
ON AN HP:
HP-2848-LA-CAR-R8-1# show spanning-tree
Rapid Spanning Tree (RSTP) Information
STP Enabled : Yes
Force Version : RSTP-operation
Switch Priority : 32768 Hello Time : 2
Max Age : 20 Forward Delay : 15
Topology Change Count : 405,614
Time Since Last Change : 4 mins
Root MAC Address : 020496-51b9fd
Root Path Cost : 22000
Root Port : 43
Root Priority : 28672
Any ideas?
7 REPLIES 7
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‎08-14-2017 09:23 PM
Hi Tom,
Yes. You are correct. You will only need to configure the ports with hosts connected (Servers/PCs etc..) as edge ports and not the trunk links between switches.
Please let us know if you have any other questions.
Thank you.
Best regards,
Andrew
Yes. You are correct. You will only need to configure the ports with hosts connected (Servers/PCs etc..) as edge ports and not the trunk links between switches.
Please let us know if you have any other questions.
Thank you.
Best regards,
Andrew
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‎08-14-2017 09:23 PM
You should always specify a root bridge, otherwise the system will determine a root bridge based off of MAC address and that can be unpredictable. all your nodes will block or forward based upon path to that root bridge, so usually it is place pretty centrally in the environment.
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‎08-14-2017 09:23 PM
Thanks Andrew, also any reason to specify a designated root bridge?
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‎08-14-2017 10:49 AM
Hi Tom,
Please bear in mind that if the user ports of HP switch are not configured for edge port (or PortFast in Cisco terms) then each time a PC disconnects/connects you will get a Topology change. So you should configure edge ports on both switches' user ports.
Also, you can prevent the ARP entries from being cleared when a TC occurs by enabling iparp fast-convergence. Please see below article.
https://gtacknowledge.extremenetworks.com/articles/How_To/How-to-prevent-topology-change-impact-on-r...
Please bear in mind that if the user ports of HP switch are not configured for edge port (or PortFast in Cisco terms) then each time a PC disconnects/connects you will get a Topology change. So you should configure edge ports on both switches' user ports.
Also, you can prevent the ARP entries from being cleared when a TC occurs by enabling iparp fast-convergence. Please see below article.
https://gtacknowledge.extremenetworks.com/articles/How_To/How-to-prevent-topology-change-impact-on-r...
Emre Kurtman
Technical Marketing Engineer / Extreme Networks
