Exchange congestion and your ISP. What you need to know...

Crystal Web

Crystal Web representative
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Joined
May 24, 2014
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3,978
#1
Can I ask another question which doesnt seem to have been clearly answered. I understand that the equipment in the exchange is managed by Telkom despite being dedicated to either IS or Mtn as the case may generally be. This would imply that congestion likely happens on a service provider specific basis. i.e. if I the exchange is continually congested than the best option for me would be to change to the alternative provider as his equipment is not likely to be as congested (could possibly be worse) but at least the point is that it would be different?
Let's address a few misconceptions and try to help out here for those who would like some more info on this:

OK, since the previous post from Afrigenie that lead to the above post about dedicated ISP hardware at the exchange, we've seen some questions start spouting our way about it now. Let me put this to rest for you: the ISP has no dedicated hardware at an exchange - there's simply no need for it and it would be financially ridiculous for Telkom to do so. I suspect that some people don't quite understand the cost of enterprise-grade routing infrastructure and the number of ADSL exchanges around SA, if they're to believe this. It would result in a couple-hundred million Rand investment Telkom were making into each backbone provider, for what return or purpose?

There is a dedicated set of IP pools that belong to the ISP, allocated over shared hardware. If for whatever reason Telkom have seen fit to allocate an ISP their own piece of hardware for whatever reason, at one or two exchanges, it is not policy, nor because the ISP is supposed to have dedicated hardware there. Telkom exchanges operate on a shared infrastructure basis, and their resources are sufficient to operate multiple IP pools and routing rules over this shared infrastructure. Occasionally however, a port, or router becomes faulty. This may disappear when using another ISP, because it may just happen that that IP pool doesn't route over the faulty port or router. If you see this happen, the likelihood is that the exchange's backhaul links are not congested, but there's a specific fault at the exchange that needs to be reported. An ISP cannot report this, but we can assist by helping you to identify the NAS port for Telkom to look at. If your line is not with your ISP, you must do the fault reporting, because this is shared infrastructure, not dedicated. It is a normal, and occasionally expected fault (because even enterprise grade equipment sometimes fails).

What if you still see problems on the second hop, but they're inconsistent? Well it's probably congestion, sorry to say. And again, not something an ISP can help with, as resolving congestion relief requires investment by Telkom into the exchange. It's not something a Telkom tech can do. All that a Telkom tech can do is submit a motivation via the area manager for an upgrade. Such an upgrade goes through a lengthy approvals process, as it is primarily a financial decision that must be made.

Are all second hop problems related to congestion? No. And in fact we find that many are port problems, as the backhaul links are not running at capacity. Often, there may also be actual line faults causing this resulting in the wrong power being delivered to the port as well.

So the bottom line:

Are all problems on the second hop indicative of exchange congestion? No, and it's not always fair to jump to that conclusion and blame Telkom.
Can it be identified that the problems are congestion related? Yes, but require much deeper investigation and signification amounts of cooperation from Telkom.
Is exchange congestion ISP related? No, it physically cannot be. The exchange sits before the ISP's infrastructure.
If your line is migrated to an ISP, is it their responsibility to "fix" exchange congestion? No. Congestion at an exchange is actually just increased contention. It's not necessarily a technical fault. It's, for lack of a better phrase, a financial one.
If your line is migrated to an ISP, is it their responsibility to report exchange congestion on your behalf? Yes, absolutely.
Does reporting exchange congestion help motivate an upgrade by Telkom? Occasionally, if it's reported by enough people.
Will reporting congestion again and again improve my chances? No. You'll simply peeve off your ISP and Telkom. They use your DM number as a unique identifier when running these reports, so whether it's 2 or 10 reports from the same DM, it is counted as 1 on the report.
Is it frustrating? Yes, and we sympathise. We really do.
 
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Joined
Oct 4, 2010
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139,118
#3
If your line is migrated to an ISP, is it their responsibility to "fix" exchange congestion? No. Congestion at an exchange is actually just increased contention. It's not necessarily a technical fault. It's, for lack of a better phrase, a financial one.
If your line is migrated to an ISP, is it their responsibility to report exchange congestion on your behalf? Yes, absolutely.
Does reporting exchange congestion help motivate an upgrade by Telkom? Occasionally, if it's reported by enough people.
There is a little more to this...

Where traffic over dedicated backhaul links shows an upward trend and is nearing around 80% of capacity, that link will be placed on a planned upgrade project list.

When capital funding becomes available (it is not an operational cost as an asset is being upgraded) the planned upgrades will receive first priority. Depending on the total funds made available, it hopefully covers the cost of all the planned upgrades and leaves a kitty available for "unplanned" upgrades. It's these "unplanned" upgrades that causes heartbreak!! If no funds are available then it has to wait until April of the next year when the new year's funds are allocated.

Obviously there are separate business cases for new works (not upgrades to existing links) ... e.g. when new MSANs are built.
 

HavocXphere

Honorary Master
Joined
Oct 19, 2007
Messages
31,487
#6
Thanks DJ. Thats interesting.

On a side note...turns out UK DSL can be just as flakey as SA DSL. :(

There is a little more to this...

Where traffic over dedicated backhaul links shows an upward trend and is nearing around 80% of capacity, that link will be placed on a planned upgrade project list.

When capital funding becomes available (it is not an operational cost as an asset is being upgraded) the planned upgrades will receive first priority. Depending on the total funds made available, it hopefully covers the cost of all the planned upgrades and leaves a kitty available for "unplanned" upgrades. It's these "unplanned" upgrades that causes heartbreak!! If no funds are available then it has to wait until April of the next year when the new year's funds are allocated.

Obviously there are separate business cases for new works (not upgrades to existing links) ... e.g. when new MSANs are built.
Its unfortunate that its a yearly cycle though...with a bit of bad luck you can just miss the cycle and be stuck paying for a congested ADSL line for 12 months. :/

I guess there is no perfect solution though...
 

Paul Hjul

Honorary Master
Joined
Aug 31, 2006
Messages
14,909
#7
there really is no perfect solution ...

the goal of course is to create an ecosystem in which the possibilities frontier is expanded and people get the right mix between various aspects of quality and price to give consumers a product worth taking up and getting magic happening: it makes no sense to have a 100Mbps downstream connection that constantly drops, nor does a consumer benefit from a 128kbps synchronous connection - regardless of how reliable it is

dedicated fibre to the home would be awesome but unless you can magically overcome the need to lay cable the finances are all off; Telkom mucked up for several years by overvaluing their copper assets and thereby getting the pricing wrong but ultimately unless we can get the ecosystem right Telkom's capital constraints are going to keep the industry back

this is why things like LLU and getting the correct mechanisms by which capital can be injected into lagging iECNS licence holders is so important - Neotel's acquisition as a going concern
 

Giles

New Member
Joined
Jan 8, 2012
Messages
8
#8
Thanks for the explanation Crystal Web - confirms what I have long suspected. I too have been experiencing on-going intermittent network congestion (high latency) issues. I duly report them to my ISP (Afrihost who manage my ADSL line too) only to have them blame the aging Telkom exchange, the weather, the proximity of remote controlled gates and even Christmas lights on one ocassion! An ADSL port reset generally solves the problem and may or may not require a physical router reboot to get things back to normal. Sounds fairly simple although having to convince Afrihost to do this every day and sometimes more than once a day does grow a bit tiresome. My ISP doesn't always report the network congestion (high latency) issue to Telkom but they will if you ask. This is all well and good but here's the problem - Telkom only respond 48-hours later and generally by the time the assigned Telkom tech gets around to checking the line everythng is back to normal and he enters the "All Clear" result for the fault and absolutely nothing gets fixed. Then I experience network congestion (high latency) again and the process repeats itself in a never ending cycle of no results. It is beyond frustrating and irritating in the extreme and there isn't a thing we can do about it. So in true South African form we simply have to settle for 3rd world service at 1st world prices!
 

r34p3r.

New Member
Joined
Nov 22, 2017
Messages
3
#9
hey sorry guys i'm not sure where to post this so ill ask here as i see it about telkom exchange and adsl.
i'm trying to figure out if i get adsl how far from exchange can i be before i wont get my full 4mb line speed?
+i need a map of telkom exchanges for Dundee KZN and Pitermartizburg Kzn i searched forums and came across this link but it dose not seem to work any more http://www.broadbandstats.co.za/maps/ any help and advice will be appreciated thank you r34p3r. :)
 

beesboertjie

Senior Member
Joined
Jun 13, 2017
Messages
521
#10
Hi r34p3r. Due to 15% to 20% protocol overheads, you won’t get your full 4 Mbps. By road (by car) I stay 500 metres from the exchange, but the length of my copper wire to the exchange is 800 metres. On my 4 Mbps line my download speed is 3,4 Mbps and my upload speed is 0,4 Mbps.

Our local Telkom technician Oupa says ADSL only works up to 2 km. He says 3 km is too far.

attenuation-copper-length-km.png
 

matador86

New Member
Joined
Apr 27, 2018
Messages
5
#12
I'm not a network guru so forgive my ignorance if some of my questions Tutuapp 9apps Aptoide or terminology don't make sense. I'd appreciate it if you set me straight if I have basic misunderstandings about what limits NBN speed.
 
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