Re: Spectrum & GRE

[Brendan Carlson via NANOG <nanog () lists nanog org>]

Yeah, that's exactly what I have seen in the past. No esp packets coming
back, they're dropped incoming when in bridge mode. I have had better luck
with a replacement modem sometimes.

--Brendan

On Mon, May 12, 2025, 17:41 Christopher Aloi via NANOG <
nanog () lists nanog org> wrote:

> Thanks Eric and Brendan.  Yes, this is specifically related to when we put
> the rac2v1s in bridge mode and I bind one of the static public IP addresses
> to my router.  If I captured packets on my router I can see GRE packets
> leaving my router destined for my data center, but I never see any of the
> return packets I send.  They are being lost/dropped on the way back in.  I
> am up to 30 of these now.  What I can't grock is why they come in at a rate
> of ~5 every morning.  If anyone has any contacts at Spectrum that might
> listen, or a workaround, please let me know!
>
> On Mon, May 12, 2025 at 4:04 PM Eric C. Miller via NANOG <
> nanog () lists nanog org> wrote:
>
> > Sorry, no help from here per se, but I used to get into the same
> situation
> > with AT&T Uverse routers. It seemed to be an issue with the built-in
> > stateful firewall of the DSL router. I was able to get around it by
> having
> > tunnels to multiple public IPs and rotating their usage with a script on
> > our equipment. The problem seems to self-resolve after a reboot. Very
> > frustrating when you pay for static IPs.
> >
> > Good luck!
> >
> > Eric
> > ________________________________
> > From: Brendan Carlson via NANOG <nanog () lists nanog org>
> > Sent: Monday, May 12, 2025 3:20 PM
> > To: North American Network Operators Group <nanog () lists nanog org>
> > Cc: Brendan Carlson <brendan () bcarlsonmedia com>
> > Subject: Re: Spectrum & GRE
> >
> > I've seen the same thing on those same models with them being in bridge
> > mode specifically. They generally have issues with gre and l2tp tunnels.
> >
> > On Mon, May 12, 2025 at 12:13 PM Christopher Aloi via NANOG <
> > nanog () lists nanog org> wrote:
> >
> > > Hey All,
> > >
> > > Hoping someone can lend a hand here.   I have ~ 1k customers running
> GRE
> > > tunnels back to me for VoIP.  Over the last three weeks these tunnels
> > have
> > > started to break at a rate of 3-5 per day.  We've narrowed it down to
> > > customers using specific Spectrum routers (rac2v1s and rac2v2s).  I am
> > > still able to access the public IP but the tunnel drops and will not
> come
> > > back up.  The fix has been to reconfigure as VPN or have the CPE router
> > > replaced with a rac2v1k.  I have been unable to get anyone to listen to
> > me
> > > at Spectrum as these accounts are owned by the customer and I can't
> > prove a
> > > systemic issue.  I have a list of accounts that have been impacted.
> Has
> > > anyone else encountered this?  Any contacts at Spectrum that might
> listen
> > > to me?  I am fearing all of these tunnels will go down at some point.
> > >
> > > Thanks,
> > >
> > > Chris
> > > _______________________________________________
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