Cisco FlexLinks and PVST

[nabeelcse07]

Hi All,

Currently I am working on a project where are using Cisco PVST for our different VLANs that are

175  --- Management

176 --- PAGA SYSTEM

177 --- CCTV System

178 --- ACS System

179 --- TEL

We are having a situation from where two cables are coming from CCTV servers and terminated on Cisco Switches that are stacked. When STP is running, its not blocking the Redundant link and showing both ports as Desg state. 

Then I configured Flexlinks on those ports and it was working fine.

Now, my question is, is it OK if I am using Flexlinks on some of the ports and at the Same time STP is running as well. Moreover, I am also observing CPU utilization of more than 50% on all switches while only 5 cables are connected to each switch.

Regards,

NA

[Reza Sharifi]

Hi,

FlexLinks are designed to be used for uplinks between Cisco switch that support FlexLink.  So, not all Cisco switches support it.

I have never seen FlexLink towards an end device (server, PC, Camera, etc..).

I suggest revisiting the STP issue and fixing it, so one link is blocked while the other one is forwarding. 

The other option would be to put both links from the server in a Portchannel if the server OS support it.

This way there is no blocking at all since both physical links would look as one logical link.

HTH

[Joseph W. Doherty]

"We are having a situation from where two cables are coming from CCTV servers and terminated on Cisco Switches that are stacked. When STP is running, its not blocking the Redundant link and showing both ports as Desg state. "

Unless the server effectively bridges the two links, STP won't see a loop and not block one of the links.