Cisco switch losing connectivity from network when trying to move...

[StretchedTech]

I recently set up a cluster management on 7 switches in my network. We are running two Cisco Catalyst 2950 switches, 2 Cisco Catalyst 2926r switches, and 3 2924r switches. Ever since i set up the cluster management we have been experiencing connectivity issues when moving workstations form the switches. The switches will lose connectivity for about a minute and then come back up. Any suggestions on what the problem could any help would be appreciated. If any more information is needed please let me know.

Thanks in advance
Hugo

 

[fynx]

Hi Newb,

First thought is, are you using portfast on your host ports? All switch ports by default will participate in spanning-tree, which when you connect a device to a spanning-tree port will go through the stages - listening - learning then forwarding or block. This process can take around 90 seconds, before forwarding traffic. To disable spanning-tree on select ports use the interface configuration command,

switch(config-int)# spanning-tree portfast

this will enable the port to go immediately into forwarding state.
WARNING: Only use portfast on HOST ports, i.e. ports that connect to an end device such as a PC or printer. Under no circumstances should you enable portfast on a port that is connected to another network device.

If you are already using portfast then you may be seeing aging time problems when moving machines around. The switch populates a MAC table which provides a map between MAC address and which port the switch can find that MAC address. There is an aging time for this table, which may cause a short interruption when moving from one port to another - it is possible to reduce this aging timer, but not recommended as you can run into issues such as asymetrical routing.

Let us know if you need any further help.

Good Luck,
Phil.

If everything is coming your way then you're in the wrong lane.