Router Stats

GunJack

cutter - did you get DMT working okay ??

Gratis

Um...forgive me, but you eminent experts in Internet technology have confused me.

I was always given to understand that a router is the thing that enables local devices to connect to each other and that the thingy which connects devices to the Internet is a modem.

To me, in my ignorance, the OP’s log appears to be modem stats, not router stats.


What you have written thus begs four questions.

1. If a “router” is capable of performing all the complex Internet synchronisation tasks to which you allude, what role does a modem play in any of it? :huh:

2. How come I can connect my computer to the Internet by attaching it to a modem - without using a router at all? :huh:

3. How come my router can’t connect to the Internet by itself? :huh:

4. How come my router offers no socket with which to connect it to my telephone line? :huh:

I would be most grateful you could explain these mysteries to me. :A


(PS. I’d also like to know who “cutter” is, what DMT means and what would be set loose in “the time taken by the router in re-assembling the split packets and if necessary doing the Reed-Solomon error correction function to correct for the errors” - would it be dangerous?

But first things first; please would you be considerate enough to start with the four basic questions that I have asked; this is a steep learning curve for a non-techie and we can get on to the more complex things later!)

GunJack wrote: »

cutter - did you get DMT working okay ??

ChiefGrasscutter wrote: »

So either your download speed will be slightly reduced by the inability of the router to connect as fast as it might if it was on Fast path, or you will loose something in the time taken by the router in re-assembling the split packets and if necessary doing the Reed-Solomon error correction function to correct for the errors.

Thanks in advance, guys.

rmg1

Gratis wrote: »

Um...forgive me, but you eminent experts in Internet technology have confused me.

I was always given to understand that a router is the thing that enables local devices to connect to each other and that the thingy which connects devices to the Internet is a modem.

To me, in my ignorance, the OP’s log appears to be modem stats, not router stats.


What you have written thus begs four questions.

1. If a “router” is capable of performing all the complex Internet synchronisation tasks to which you allude, what role does a modem play in any of it? :huh:

2. How come I can connect my computer to the Internet by attaching it to a modem - without using a router at all? :huh:

3. How come my router can’t connect to the Internet by itself? :huh:

4. How come my router offers no socket with which to connect it to my telephone line? :huh:

I would be most grateful you could explain these mysteries to me. :A


(PS. I’d also like to know who “cutter” is, what DMT means and what would be set loose in “the time taken by the router in re-assembling the split packets and if necessary doing the Reed-Solomon error correction function to correct for the errors” - would it be dangerous?

But first things first; please would you be considerate enough to start with the four basic questions that I have asked; this is a steep learning curve for a non-techie and we can get on to the more complex things later!)





Thanks in advance, guys.

No doubt someone will correct me if I get any of this wrong, but here goes:-
1) A modem is needed to connect the computer to the internet. Most modern routers have a built-in modem.
2) See above. To put it in it's simplest terms, a router is a switch which allows multiple devices to connect to the same modem.
3) If it's a router, it should be able to, but then you have ethernet switches whoch don't have a modem "attached" and need connecting to a modem.
4) It's probably an ethernet switch not a "proper" router.

"cutter" is a shortened form of ChiefGrassCutter but I don't about the rest of it, sorry.

kwikbreaks

Gratis wrote: »

what DMT means and what would be set loose in “the time taken by the router in re-assembling the split packets and if necessary doing the Reed-Solomon error correction function to correct for the errors” - would it be dangerous?

The first bit has pretty much been answered but in short the OP just said router when what he has is a combined ADSL modem and router - it's pretty common usage to do so. You must have what's known as a cable router - that is it's just a router with no inbuilt modem.

right..

DMT is a piece of software that can work with some adsl modem routers to override the default target noise margin sync is attained at.
http://dmt.mhilfe.de/
This can be handy if you want to alter the default speed/stability ratio or "tune out" an over pessimistic target which the BT line management has set. It also produces reams of useful stats and graphs. Useful only if you know what you're looking at of course otherwise just eye-candy.

Reassembling the data packets when interleaving is in effect takes time so the latency (ping) is increased. Apart from the initial small delay there is no other overhead as data continues to arrive while the de-interleaving and error correction is done. http://www.kitz.co.uk/adsl/interleaving.htm explains it all far better than I could.

===actually after reading through that I see I forgot the extra error correction bytes - only a minor extra overhead though ===

Not sure what you mean by dangerous - if you meant DMT then injudicious use of it can screw up both the connection and the BT set profile which can take an age to self-correct. Used correctly it can be very useful indeed so long as you understand what you are doing.

ChiefGrasscutter

Most modern units are combined router/modems to use the accurate term but these are now universally referred in general conversation as 'routers' alone.
Technically speaking a modem is something whose sole purpose is to interface with a telephone line.
You are correct in that the stats quoted in the OP post are modem stats, but given that most units as I've just said are combined router/modems this distinction is now lost and even the ISP's will tell people to post their 'router stats' in response to a query.
Indeed most units have a webpage style interface and looking at the various subpages you would have no idea which page refers to the modem part and which to the router part.

The reference to DMT in an earlier post is to a specialist program of German origin to analyse broadband lines and detect which frequencies are being lost due to interference on the line. The program only works on certain router/modem units.
Message to poster 'Gunjack' here - yes I did get the modified version to work - thanks a lot for your help.

Reed Solomon error correction and interleaving is very complex to explain.............
The data you receive is split into packets for ease of sending. Each packet you get has additionally some "check bits" added on the end made up of a mathematical calculation made from the data in the packet itself. Your router/modem also does this calculation and compares its calcs' from the the packet of data received with the value of the 'check bit' sent by the exchange. If they tally all is OK, if they don't an error has occured in the transmission and the packet is corrupted. It is possible sometimes to re-assemble the now corrupted packet of data based on the value of the 'check bit'. This is Reed Solomon error correction and your router will be doing this as a matter of course without you knowing. Furthermore to add even more complexity to the error correction the data packets are not sent in a continuous sequential stream. They are slightly mixed up...and then reassembled into the correct order at your end by the router/modem. This is to avoid sudden short bursts of 'noise' on the line totally destroying a whole block of data and making data correction impossible. This is called interleaving where part of the data packets are inteleaved into other parts and in other words it makes it easier to re-create data using the check bits.
Interleaving is used on longer lines which are more suseptible to 'noise' and is not used on shorter lines. It is set on or off by BT/the ISP depending on the line's characteristics and generally cannot be changed - yeah I know there are exceptions.
If interleaving is off no error correction is done and hence no check bits are required to be trasnmitted and there is less time spend by your router/modem re-assembling the mess at your end and hence your internet will be slightly faster.
The actual creation of the check bits is subject to complex mathematics to ensure the check bits are unique to the data packet...so the data packet can be very precisely and accurately re-assembled at the far end should a section be 'lost in transmission'.

That was a highly simplified description of error correction!

rmg1

Quick question (I hope), how do I tell if I'm on interleaved or fastpath?
I'm quite a distance from the exchange (around 3.5KM).

ChiefGrasscutter

rmg1 wrote: »

Quick question (I hope), how do I tell if I'm on interleaved or fastpath?
I'm quite a distance from the exchange (around 3.5KM).

I'd just that at that distance I'd guess you'd be interleaved: I'm assumed that 3.5Km is the distance as the cable runs
I'm interleaved at 2.2Km.
I don't personally know anyone not interleaved but I'd hazard a guess that at 1km or less one would be on Fast - but it does depend on the line quality. Rural overhead lines might be interleaved right up to the exchange doorstep, urban underground lines less suseptible to impulse noise might be 'Fast' for a further distance out.

Somewhere in your Router/modem stats page(s) there should be a statement that the line is "interleaved" or "interleave" alternatively 'Fast Path' some just called 'Fast'. Usually it's near the top of any listing.
On my Dlink is under "Type" and on my Voyager it under "Latency Type"

kwikbreaks

If you can't see interleave or fast mentioned in the stats see if there are any error stats reported - you only get FEC errors on interleave (they are the ones that the error correction fixed).

GunJack

wow- you guys have been busy

just my tuppence-worth on a couple of points....

1. Fastpath/Interleaving - really depends on how stable your line is rather than distance from the exchange, e.g. I'm on a 50dB line and used fastpath for a while, just to see how much difference the lower ping made on ps3/xbox gaming. Now my line is pretty stable (I usually tweak down to 2.5-3 dB snrm using DMT on a D-Link 2640B), and fastpath worked quite well. Lower sync using slightly higher snrm (from memory, 5.5dB and approx 700k slower sync) but got same throughput with slightly reduced ping (down from 28ms on interleaved to 18ms on fastpath).

2. Line profiles are more often than not defaulted to Interleaved, but all you need to do with most ISPs is ask them to change you to fastpath. e.g. I tried fastpath for a few weeks, then rang them back and got it changed back to interleaved.

3. some "even less" techie ISPs still refer to fastpath as "gaming mode" :think: 'coz it is popular with....errrmm.... gamers !!

4. DMT and RouterStats are pretty essential router tools for anyone who's at least half-serious about their broadband. Even without the ability to tweak your line (snrm therefore connection speed) the data/graphs both produce show exactly how your line is behaving, so if you do ever have a line/exchange problem, you can tell your ISP EXACTLY what's going on. I monitor my line 24/7 (and tweak my snrn) using DMT. I used this to great advantage around a year/18 months ago when I had a line fault. Soon got it fixed when I showed mr Openreach what kind of unstable snrm and random drop-outs I was getting (corroded joint due to standing water in first junction box from my house).

5. 'cutter - got your pm, ta

6. maybe I ought to think about getting a life

AirCooledHeaven

UncleZen wrote: »

You are correct. I live < 1 mile from the exchange. My speeds have been as high as 6.5M but the reason I ask is that its more likley these days that my speeds are 1MB and even 400K, yes you read that right same upload & download speed (iPayer impossible).
One day I tested (thinkbroadband speedchecker) every 15mins, I got: 700K, 1MB 3MB, 900K - go figure.

Considering you are so close to the exchange you appear to have a relatively poor downstream noise margin of 7db. Not sure what router you're using but my netgear router gets flaky when the downstream margin hits 6db or lower. Might be worth asking BT to check the line and also try a different microfilter. Another thing to try is to disconnect everything from the socket (telephone, answerphone, filter) and check the stats again with just a direct connection between the socket and the router.