HavocXphere
Honorary Master
Since questions about exchange congestion keep popping up I thought I'd do a write-up that can be linked to.
What is exchange congestion
Exchange congestion occurs when the ADSL users connected to a specific exchange move more data than the exchange can handle. The effect is much the same as a traffic jam on a highway...everything slows down and everyone is late for work. On the ADSL side this shows up as high latency ("ping") and reduced throughput ("download speed"). Gaming, skype and other real-time activities will be hardest hit, though the effect on streaming (youtube) will be noticeable too. The throughput is generally an unreliable indicator for this so we're going to focus on latency.
How do I test it
By performing a trace route ("tracert"). This plots a path from your PC to the website you select and reports how long it took to reach each "hop" along the way. This gives us a way to distinguish between a bad ISP and a bad Telkom exchange [SUP](Note 1)[/SUP].
To perform a trace route, you need to open a command prompt window. To do so, hold down the Windows Key (between left CTRL and left ALT) and press R. That opens the Run window. Type in "cmd" (no quotation marks) and hit enter. This opens a black window. Type in "tracert mybroadband.co.za" (no quotation marks).
What am I looking for?
I happen to have both a congested and an uncongested trace for my line (Same line, same ISP, different exchange)
In the above congested exchange example its taking almost half a second to make it through the first hop. Thats enough to make most fast paced games unplayable simply due to exchange congestion - regardless of how "good" your ISP is. Anything above 25 is suspicious and above 100 is pretty much guaranteed to be a problem. Note...this is for first hop only...seeing 100+ on later hops is normal if its an international site.
Exchange congestion can also depend on the time of day - a semi-congested exchange will only show symptoms during peak times. Friday afternoons and Saturdays are usually worst. If you've got a semi-congested exchange chances are you'll have a fully congested exchange a couple of months later.
How do I fix it?
Sadly, the answer is usually that you don't. Usually Telkom needs to physically upgrade the exchange hardware. You can try reaching out to Telkom support channels, but understand that its a long shot - very very few people have managed to get this fixed without waiting & some have been waiting for years.
Technical Note 1
While the above is reasonably reliable (esp if it indicates a good outcome), technically a bad ISP can affect the first hop too since ISP IPC congestion will look the same. The easiest way around this is to re-do the test with a different ISP. So either purchase some cap from a different ISP or use the Telkom guest account (assuming your primary account isn't Telkom already)
Username: guest@telkomadsl
Password: guest
NB - the above can only navigate to specific sites. The most interesting being saix.net since it also has a speedtest tool on it. i.e. You'd need to use saix.net instead of google.co.za
Technical Note 2
The sharp eyed people will have spotted some differences in the IPs on the tests both in route and end point. Its just Google & IS reshuffling things - the traces were taking almost a year apart. It doesn't affect the overall example though (I checked) so ignore it.
Technical Note 3
As per ranger's comment below using the test account is superior from a testing point of view to a standard Telkom Internet account.
(Also - in case someone missed it - ranger is considered a trusted source of info on the technical ADSL front).
Closing Thoughts
The above is what I do. No doubt others will have different opinions & some like using tools that present the above in a visual format etc. There is also an automated tool available written by a mybb member (I've never used it so can't vouch for it):
http://mybroadband.co.za/vb/showthread.php/607090-quot-Is-it-my-Line-quot-Report-Tool
@mods: OP permission hereby granted to edit & improve as necessary
What is exchange congestion
Exchange congestion occurs when the ADSL users connected to a specific exchange move more data than the exchange can handle. The effect is much the same as a traffic jam on a highway...everything slows down and everyone is late for work. On the ADSL side this shows up as high latency ("ping") and reduced throughput ("download speed"). Gaming, skype and other real-time activities will be hardest hit, though the effect on streaming (youtube) will be noticeable too. The throughput is generally an unreliable indicator for this so we're going to focus on latency.
How do I test it
By performing a trace route ("tracert"). This plots a path from your PC to the website you select and reports how long it took to reach each "hop" along the way. This gives us a way to distinguish between a bad ISP and a bad Telkom exchange [SUP](Note 1)[/SUP].
To perform a trace route, you need to open a command prompt window. To do so, hold down the Windows Key (between left CTRL and left ALT) and press R. That opens the Run window. Type in "cmd" (no quotation marks) and hit enter. This opens a black window. Type in "tracert mybroadband.co.za" (no quotation marks).
What am I looking for?
I happen to have both a congested and an uncongested trace for my line (Same line, same ISP, different exchange)
Congested Exchange said:
Uncongested exchange said:
In the above congested exchange example its taking almost half a second to make it through the first hop. Thats enough to make most fast paced games unplayable simply due to exchange congestion - regardless of how "good" your ISP is. Anything above 25 is suspicious and above 100 is pretty much guaranteed to be a problem. Note...this is for first hop only...seeing 100+ on later hops is normal if its an international site.
Exchange congestion can also depend on the time of day - a semi-congested exchange will only show symptoms during peak times. Friday afternoons and Saturdays are usually worst. If you've got a semi-congested exchange chances are you'll have a fully congested exchange a couple of months later.
How do I fix it?
Sadly, the answer is usually that you don't. Usually Telkom needs to physically upgrade the exchange hardware. You can try reaching out to Telkom support channels, but understand that its a long shot - very very few people have managed to get this fixed without waiting & some have been waiting for years.
Technical Note 1
While the above is reasonably reliable (esp if it indicates a good outcome), technically a bad ISP can affect the first hop too since ISP IPC congestion will look the same. The easiest way around this is to re-do the test with a different ISP. So either purchase some cap from a different ISP or use the Telkom guest account (assuming your primary account isn't Telkom already)
Username: guest@telkomadsl
Password: guest
NB - the above can only navigate to specific sites. The most interesting being saix.net since it also has a speedtest tool on it. i.e. You'd need to use saix.net instead of google.co.za
Technical Note 2
The sharp eyed people will have spotted some differences in the IPs on the tests both in route and end point. Its just Google & IS reshuffling things - the traces were taking almost a year apart. It doesn't affect the overall example though (I checked) so ignore it.
Technical Note 3
As per ranger's comment below using the test account is superior from a testing point of view to a standard Telkom Internet account.
(Also - in case someone missed it - ranger is considered a trusted source of info on the technical ADSL front).
Closing Thoughts
The above is what I do. No doubt others will have different opinions & some like using tools that present the above in a visual format etc. There is also an automated tool available written by a mybb member (I've never used it so can't vouch for it):
http://mybroadband.co.za/vb/showthread.php/607090-quot-Is-it-my-Line-quot-Report-Tool
@mods: OP permission hereby granted to edit & improve as necessary
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