Re: Spectrum & GRE

[Josh Luthman via NANOG <nanog () lists nanog org>]

There was a frustrating issue with SIP on Spectrum a while back:
https://www.reddit.com/r/networking/comments/tt4hwo/followup_on_spectrum_is_rate_limiting_voipsip/

There really isn't a good answer other than to keep squeaking till greased.

On Tue, May 13, 2025 at 9:40 AM Andrew Plas via NANOG <nanog () lists nanog org>
wrote:

> A good 10 years ago I had this issue with DMVPN on Cisco routers plugged
> into Charter modems in bridge mode mysteriously dropping ESP.  Some were
> fine, some were terrible.  I worked around the issue by sourcing the tunnel
> from a loopback interface and enabling NAT so the tunnel was NAT-T using
> udp/4500 instead of ESP.  Magically, no more issues.  I am surprised to
> hear this is still an issue.  Those sites are all Silverpeak SDWAN now with
> the same modems and no issues- Silverpeak uses udp/12000.
>
> Andrew
>
> On Mon, May 12, 2025 at 7:54 PM Brendan Carlson via NANOG <
> nanog () lists nanog org> wrote:
>
> > 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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