[cisco-voip] New install 11.5 phones won't register or the subscriber

[Mike King]

On Wed, Oct 11, 2017 at 4:10 AM, Ryan Huff <ryanhuff at outlook.com> wrote:

>
> - Make sure you’re accounting for any non-standard MTU between the
> publisher and subscriber nodes. By default, CUCM will use 1500 if you don’t
> change it (which is the typical network standard). For example; If you have
> jumbo frame support in the network path between the two nodes and you set
> 1500 MTU on the publisher and subscriber, the subscriber installation will
> typically “fail node connectivity validation” with no visible clue as to
> why. This is because this is the first point in the subscriber installation
> where there is enough back/fourth TCP with the publisher to cause the TCP
> window to burst, which causes the TCP retransmission error. Since it
> happens at this point, CUCM assumes it’s because the publisher can’t verify
> the subscriber.
>
>

Hey Ryan,  Do you have links for that?  I find the behavior very odd, and
not the way I understood standard MTU over a Jumbo enabled network to
function.   Or is this just a Cisco Caveat type deal?

Mike
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