Does Topology Change have impacts on the Network

jskfan
jskfan used Ask the Experts™
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Does Topology Change have impacts on the Network

I would llike to know when there is TCN in the Network whether this can impact End Users and Servers.

The reason for this question, is I believe that Switches do not perform in a timely manner, they can have delays because of CPU or Memory over usage..
So I wonder if TCN is normal behaviour or it can cause disruption in the network

Thank you
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mikecrIT Architect/Technology Delivery Manager

Commented:
What type of topology change are you talking about? A routing topology change or a spanning-tree topology change?

Author

Commented:
spanning-tree topology change.
For instance when a port goes from blocking to listening or from forwarding to blocking.
IT Architect/Technology Delivery Manager
Commented:
Yes, this can have a negative affect on your network if you don't have spanning-tree configured properly.  That's why each port should be identified as to what is plugged into it and have spanning-tree set accordingly, especially if there is a switch on the other end of the port. Too many switches on a network sending BPDU's can cause increased processor and memory utilization. That's why I normally look at the design of the network and make sure that there are no network loops. I also use the patch cost command (in a Cisco environment) to influence how I want my traffic to flow.
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Author

Commented:
Other than the Design. I do not think there is anything to configure in STP. It is on by default.

I agree the design is important.. for instance do not link Access Switches redundantly
ex: Access Switch1 will connect to Access Switch2,  Access Switch2 will connect to Access Switch3, but not back to Access Switch1
Kind of Linear connection.

Then Each Access Switch can have 2 links aggregate  to each Distribution switch that use VSS and the VSL is also
aggregated...

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Some networks that do not have budget for Stackable Switches or VSS can have L2 redundant Links, for instance L2 swicthes connected in triangle or rectangle way,   in this case there will be  blocked , Designated, Root ports...
I was assuming that the delay in sending BPDUs or Hellos because of Resource constraint can cause topology change

Author

Commented:
That's why I normally look at the design of the network and make sure that there are no network loops. I also use the patch cost command (in a Cisco environment) to influence how I want my traffic to flow.
Is this your solution?

which design you use so that no STP loops occur ?

Author

Commented:
Thank you

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