Just to be clear, any retransmit is at the TCP level - never at the ATM level. Any corrupt ATM cell that's part of a TCP frame will just cause the TCP frame to be dropped. The ATM level will know about corrupt ATM cells and the ATM management will record those. But I must admit I've been retired too long and forgotten at what point the ATM layer considers the line errors too much and attempts dropping the connection and doing a retrain.
Snip excellent explanation of things I hoped never to need to know:-)
There have been 5 re-connections this evening:- 16-28 to 18-04 plus a further 11 100% packet loss events.
Plusnet are clearly embarrassed as they are re-funding some money!
I thought twisted pair cabling was intended to minimise these issues?
Wind dropped off a bit now but still blowing:-)
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Ha! Taking a chainsaw to a few suspect poles might get some attention! Actually, response has been within 24 hours so my only criticism of Openreach is that climbing the poles is clearly a last resort:-(
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Yes, in theory any interference will be common mode. Such that the same signal will manifest on both conductors at the same time.
I'm not sure how good ADSL routers are with extremes of common mode input voltage.
The vast majority of the latency of a *given packet length* is the time it takes to move that packet down the local link - the ADSL or VDSL.
The total latency is that plus the speed of light delay, which is pretty damn small really.
In general latency is dominated by how fast your broadband connection actually is. Sometimes by how congested it is and sometimes by the retransmit time if a packet gets lost or corrupted beyond repair.
No, they dont.
ATM is not a feature of ADSL. ATM happens at the DSLAM and upstream. In general the whole packet makes it to the DSLAM unsplit unless it's over some magic figure - 1452 bytes rings a bell.
and on a dodgy line every one of
Forget all the underlying transmission protocol. At night AM radio interference is higher and it's colder.
One of those is probably affecting whatever the problem is.
It does, but minimise != eliminate.
Down ere in east anglia the peak wind was around midnight. I've not seen any trees down outside the window though. Oh maybe one. Or is that from the last storm?
Mildenhall METAR gives 15 gusting to 22 knots. So that's not a gale, but its a stiff old breeze.
We'll have to differ, but e.g. Cisco says ATM starts in the customer router
But is not *native*. It's *tunnelled*. As is PPP. So its carried over inside much larger packets
ATM traditionally was/is only *native* on BTs backbone.
ADSL was traditionally 1500 bytes or 1400 bytes MTU.
It's been a while, but my connection used to be PPPoA - IP over PPP over ATM, over VDSL
The VDSL part drops at the DSLAM giving IP over PPP over ATM - that's what gets/got routed to the ISP.
PPPoE was another possibility - at some magic level BT could provide Ethernet presentation for the ISP and presumably either tunnel THAT over ATM or use something other than ATM for backhaul. My knowledge runs out at that point.
Is ATM *ever* a physical layer protocol?
I've used 34Mbps ATM circuits, came into the building as SDH fibre, got converted to dual coax and then ethernet.
Sadly my free use monitoring has come to an end.
There were 20 disconnections Sunday night/Monday morning.
Plusnet still have this as an ongoing fault but seem reluctant to invest further in Openreach visits. Cue refunds to shut me up!
Current speed now down to 500kB!
Plusnet are *obliged* to pass the fault back to Openreach.
There is nothing else Plusnet can do. They have replaced all the kit it is in their power to replace.
Now down to 283Kb. Tempting to put the old router back.
Barclays won't even let me log in! I wonder if HMRC will accept this as an excuse for late payment!
Barclays is like that. I have a folder on Barclay's ecxuses. Its called Barclaycunts
Never had any other problems. The branch I joined in 1961 is still open and still has my personal account!
Long call from Plusnet. Senior Openreach engineer booked for Friday! Current system uptime of 2h 40m so not much affected by the wind last night. It occurs to me to wonder if momentary interruptions could be due to ongoing overnight work at the exchange in preparation for fibre roll out.
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AFAIK there are no 'works at the exchange to enable fibre rollout'. The new fibre network bypasses the exchange completely..
Unlikely. If/when you get fibre, it's not likely to go anywhere near your local (assume tiny?) BT exchange or cabinets ...
Hmm. Lots of saleable building sites in developed areas!
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