[c-nsp] VSS and 3560, convergence measurement

[Pavel Skovajsa]

Hello Mkhail,

Usually VSS convergence should be below 200ms, at least on paper.... I
would try to turn off various "automatic features", starting with
trunk negotiation (DTP) on one end of spectrum and undesirable
portchannel on the other to find the culprit.

-pavel

On Sun, Nov 14, 2010 at 8:25 PM, Mikhail <hidden.node at gmail.com> wrote:
> Hello, list.
>
> We have VSS 1440 and we try to measure convergence time when we pull one of
> the copper links from 3560 (Etherchannel, PAgP, desirable-desirable, we also
> tried on-on).
>
> We do it by sending "ping -f -i 0.1 -W 0.1 <IP>" from the Linux station:
>
> Linux -- [3560] === [VSS] === [4948] --- <IP>
>
> This command prints us about 12-18 dots which is 1200-1800ms (btw, when we
> pull one of the 10Gb links from 4948 it prints usually 1-2 dots, sometimes 3
> dots).
>
> VSS design guide states that for 3xxx series port failure convergence time
> should be about 200ms.
>
> 1. Does "ping" measurement actually give us convergence time? Is there any
> "official" method for such type of measurement?
>
> 2. I suspect that 3560 is the root of the issue. Is it normal for that
> switch to converge for 1,5 second after losing one of the Etherchannel
> links?
>
> Thank you in any advance!
>
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