Cable Company Hotspots

Thomas Scott mr.thomas.scott at
Mon Nov 23 14:24:55 UTC 2020

>It shares the aggregate bandwidth of the HFC but not your contracted

That's how I remember them being provisioned, they were on the same modem,
but using their own timing slots, so essentially the subscriber at their
own premises was never using the channels at the same time as the "roaming
subscriber" who was on their own SSID. This led to some... *interesting*
setups where you could increase your bandwidth decently, but with an
increase in latency. Depending on your use case, ymmv.

is a great example of a "creative setup"

- Thomas Scott | mr.thomas.scott at

On Mon, Nov 23, 2020 at 9:12 AM Rod Beck <rod.beck at>

> It is a lifesaver. It is a good back up to have if primary services fails
> as my telco service did Friday. Transmission rates up and down vary
> dramatically from as high as 40 megs down to as low 500K down. It is
> definitely shared bandwidth in the Last Mile. 🙂
> -R.
> ------------------------------
> *From:* Rob Seastrom <rs-lists at>
> *Sent:* Monday, November 23, 2020 2:55 PM
> *To:* Lady Benjamin PD Cannon <ben at>
> *Cc:* Rod Beck <rod.beck at>; NANOG Operators' Group <
> nanog at>
> *Subject:* Re: Cable Company Hotspots
> On Nov 22, 2020, at 12:42, Lady Benjamin PD Cannon <ben at> wrote:
> >
> > Rod, that’s exactly how they are delivering it. Unclear wether it’s over
> a separately provisioned bandwidth channel, or wether it shares the
> aggregate capacity of the HFC.
> It shares the aggregate bandwidth of the HFC but not your contracted
> bandwidth.  Itmight be possible, but its extremely unlikely, to dedicate
> downstream or particularly upstream DOCSIS channels for this, and if you’re
> running docsis 3.1 “channel” takes on a rather different shade of meaning
> anyway.
> This is done with “service flows” which are part of the docsis spec.
> They’re more like CAR with an ACL than DSCP.  Your cable modem already has
> at least four service flows defined in its profile:  one each for upstream
> and downstream, cablemodem management and contracted-bandwidth commodity
> internet.   If there is a built in phone jack (NANOG would call this an
> ATA, but the cablelabs term for it is an MTA or eMTA) then add a couple of
> more flows to it for the voip.  There could be still more; uses are up to
> your imagination.
> I haven’t seen better than 10-20m service flows for guest wifi...
> Shared vs dedicated wifi radio for guest would be dependent on the CPE.  I
> believe they are mostly shared, but my information is dated at this point
> and radios have gotten stupid cheap in the meantime.
> Likewise, backhaul technology is implementation dependent; L2TP is what
> I’ve generally seen, not GRE, but again that info is five years out of date
> at this point.
> So in short, assuming minimal interference and good wifi config (which may
> be a lot to ask in some environments) someone running speedtest on the
> guest wifi should have almost no effect on your contracted network
> performance, modulo any timing effects of the docsis channel transmission
> time slot allocator.
> HTH,
> -r
> Sent from my iPad
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