Enable portfast on the host ports and you'll see a much quicker transition.
Just labbed this up and with portfast enabled I lost a single ping during
the failover. Without it enabled I lost 12.

For the VoIP question - in production I'd recommend building with
Etherchannels just so STP never needs to converge.


On Wed, Mar 9, 2011 at 5:41 PM, marc abel <[email protected]> wrote:

> I have 4 switches connected in a loop.
>
> Cat1-------------Cat2
>  |                   |
>  |                   |
> Cat3----------Cat4
>
>
> Cat 1 is the root, Cat 2 is the secondary root. All the switches are
> set to RPVSTP and I have confirmed that show spanning-tree shows RSTP
> as the protocol. Cat 4 shows it's interface to cat3 as it's root port
> and the interface to Cat3 as the Alternate. I have not tuned any
> timers.
>
> What should be the convergence time in this situation?
>
> If I run a ping from a host attached to Cat4 to a host attached to
> Cat1 and then I shut the Cat1-Cat3 interface (on the Cat1 side) it
> takes about 32 seconds before pings pick back up. I thought RSTP was
> supposed to converge in about 6 seconds?
>
> Another question, what is the fastest recovery time we can tune down
> to from RSTP? How do others tune this for VOIP? I know that I can get
> sub second convergence from OSPF but not all my switches have an
> appropriate image to run ospf.
>
>
> Thanks in advance.
>
> Marc
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