Typical last mile battery runtime (protecting against power cuts)

Brian Turnbow b.turnbow at twt.it
Fri Feb 3 17:25:47 UTC 2023


> At $day_job, I have a team of engineers who are oncall for critical services in
> the United Kingdom. For $reasons, the national power grid is announcing the
> possibility of rolling power cuts over the coming months.
> Right now it's "unlikely", but possible. If cuts do happen, it'll be 3+ hours,
> possibly several times/day.

They have been discussing it here in Italy as well.
The isp/telecommunication industry here is tryng to get Cos/pops/cabinets listed as critical infra and removed from rolling power cuts.

> Question is, how much battery runtime can I typically expect from ISPs'
> last mile infra.
> - For FTTP, I *think* (but am not sure) that the UK mostly uses PON, so guess
> it would be runtime of OLT and onwards

Here this is mainly ran from pops that have ups and generator systems so several hours to days of uptime depending on site.
OTOH I have seen providers daisy chain customer sites in a ring that crash miserably when 2 customers loose power isolating all in between sites.
But that is not the norm...

> - For DSL: runtime of DSLAM cabinet and onwards

Street cabinets for fttc services here have low times if any.
Same thing for mini dslams mounted on poles in the middle of nowhere.
0 to 2 hours for these.
Most have batteries/capacitors in the cabinet but not all and they are not designed for extended power outages 2 hours max.
Some are remotely powered from the CO, but that does not seem to be a thing anymore. Too costly
DSL ran from COs are protected as for fiber above.

> - For CATV: CMTS and onwards, maybe any active equipments in the HFC to
> the CPE?
> - For 4G: BSS and onwards

Don't operate a 4g network, so take this info accordingly ,  but here it depends on the tower from what I have seen.
All towers I have seen have  battery backup , a lot have generators too.
I would say they have higher times than the fttc times above.



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