Spectrum (Charter) Fragmented UDP

Wed Oct 2 14:05:08 UTC 2019

Wait till STIR/SHAKEN is enabled. Were going to see real quickly who isn't
handling fragmentation correctly.......

On Wed, Oct 2, 2019 at 8:34 AM Saku Ytti <saku at ytti.fi> wrote:

> Hey Phil,
>
> > At some point over night on 30th September (i.e. the night going into
> 1st October), we saw a number of Spectrum (Charter) customers stop handling
> fragmented UDP packets. This has manifested itself in such that the phones
> of affected customers are no longer receiving UDP SIP INVITE packets which
> exceed whatever their WAN side MTU is. We've so far had 6 customers report
> the issue - we can see that the last call on 30th September worked and the
> first and subsequent calls on 1st October failed.
> >
> > Is anyone aware of an update to CPE devices pushed out that night which
> may have broken their ability to handle IP fragmentation?
>
> I don't know anything specific to this case, but you'd serve your best
> interest to send small enough packets that do not need fragmentation,
> particularly in the backbone. Even devices often considered SP
> quality, such as ASR9k, fragment in the linecard CPU, giving very poor
> service quality compared to sending two packets not fragmented.
>
> While we can say this should just work, the reality is, it's not very
> reliably true and I would not build product or business on the
> assumption that it works well.
> --
>   ++ytti
>
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