Modem question...

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Modem question...

Post by woody2 » Wed 17 Nov, 2010 4:46 pm

Team,

How much does your modem effect your net speed?

Im using a Belkin Voip 802.11g modem that iinet gave me a few years back when i signed up with them.

Can I speed up my net by having a different modem?? Or is the speed only related to the connection the house has?

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Post by spitex » Wed 17 Nov, 2010 4:53 pm

ADSL Statistics - SNR/Attenuation

A quote taken from http://www.whirlpool.net.au

A high SNR simply means how loud the signal is over background noise. The higher the SNR margin the more stable the connection. You have a strong signal and have plenty of head room to receive faster speeds. Generally you would have a high SNR if your on a restricted speed plan eg. 256/64, 512/128 or 1500/256. The faster your connection speed the lower your SNR will be. Generally on unrestricted speed plans like Adsl2+ up to 24mbit the isp will set the SNR margin at which your modem connects generally a range between 6dB to 14dB. This will give you the fastest speed while maintaining a relatively stable connection. iiNet currently allow Adsl2+ customers to choose their own profile which ranges from fastest possible speed (low SNR) to slower speeds (higher SNR).

Attenuation on the other hand is a measurement of the resistance to the signal on the line and should never change regardless of speed.

There are many factors which affect both SNR and attenuation. A few are line distance, gauge or thickness of line, quality or age of line, number of bridge taps on line etc.


Generally, you will have a fixed attenuation value from the Exchange to your House. Things like Cordless phones, fax machines, in-home cabling, microwaves will affect your attenuation further. This is why DSL filtering is important.

Here are the DSL stats from my line. You will get 2 values, Upstream and Downstream. The DS Channel is the important one and is on the left.

Noise Margin: 15.0 dB 15.5 dB
Output Power: 20.0 dBm 12.5 dBm
Attenuation: 26.0 dB 13.0 dB
Speed (kbps): 13557 965


If your DSL Noise Margin is below 6db, you NEED to have your line profiled by your ISP. This will result in lower trainup speeds, but more connection stability. If you check your SNR reading frequently and they are fluctating there's something seriously affecting your line also. This can be 'water in the pits' further down the street, interference from warming a hot dog in the microwave or the Telstra guy is fiddling with equipment down the street. It really is that ambiguous. Most of these problems are solved by DSLAM profiling including interleaving.

ADSL Interleave / Fastpath

For most mum and dad internet services ISP's implement Interleaving on almost every circuit they provision. This basically determines the amount of error correction that's being proactively pushed down the line to ensure non-errored data transmission. The simple fact is, not everyone needs it. Interleaving increases the Bit Error Rate and Correction for your ADSL circuit, which inturn increases latency as there's more processing happening on transmission of data.

Some ISP's choose to supply Fast-path services as default, which don't have the same level of error correction but as a result have a minimal latency figure. Customers call up, complain of frequent sync drops and they turn Interleaving on. All of a sudden connection is stable, but latency is increased.


First Hop Latency Figures
Interleaving - 30 - 40milliseconds (Your Router to your ISP's Router).
Fast Path - 5 - 15milliseconds (your Router to your ISP's Router).

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Post by spitex » Wed 17 Nov, 2010 4:55 pm

DSL Modem/Router Tiers.

This is now basically subject to my personal opinion. There may be models that are released by manufacturers that are amazing, or are dudds. The best thing to do is take a look at http://www.whirlpool.net.au and have a look at the discussions regarding modems in everyday use.

While I have personally done some extensive testing of ADSL2+ modems in 2006, I spend my life in the top tier of hardware and don't read or follow much in the residential market.

Top Tier - As good as it gets
* Cisco 877 ADSL2+ - around about $600 - 1200 new depending on features
- (Older models still kick ass, 827/837/1721 with ADSL WIC)
- You can pickup cheap ones (2nd hand) at http://www.iptrading.com.au without too much trouble.

Better Tier for Home Use
* Billion
* Draytek

Acceptable for Home Use
* Netgear
* Belkin
* Linksys (no, despite the labelling, this isn't CISCO)
* Alcatel (Speedtouch)
* Siemens

Worst - Do not touch
* D-Link

The post above details ADSL technology and why certains things affect it/performance.

Basically, if you're close to your local telephone exchange you can get away with crappy modems but it's still not ideal. If you live a fair distance away routers like the Billion/Draytek & Cisco will give you far better connection stability and speed.
Last edited by spitex on Wed 17 Nov, 2010 5:05 pm, edited 2 times in total.

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Post by spitex » Wed 17 Nov, 2010 4:58 pm

Quick tips for Happy Internets

* If you're on ADSL/Cable do NOT FLOOD your upstream bandwidth as this will affect downstream also. (Disable torrents, unplug your room mates PC etc)

* ADSL Tips - if your ISP Supports it (most do), use ATM PPPoA/VCMUX for the ADSL and ATM framing protocol. Never ever use PPPoE unless you have to. Most people have PPPoE/LLC setup - this is wrong.

* ADSL Tips #2 - MAKE SURE YOUR LINE IS PROPERLY FILTERED! I cannot stress how important this is. I personally didn't believe it at first until I tested some of the best filters money could buy $12 each .. lol. They make all the difference.

* Get yourself a good ISP (Network) - Telstra Bigpond / Optus / Internode / iiNET

* Get yourself a good ISP (Support), that prides itself on supporting Gamers and Internet enthusiasts (Internode/iiNET) which in turn have the largest customer base doing the same things you are. If they have trouble getting to gaming servers or other popular shit, they're going to know about it.

* If you are a LONG WAY from your local telephone exchange and you're having trouble with ADSL technology, try investigate the option of using Cable internet in your area. Telstra & Optus are the only two companies who offer cable internet - both networks are as good as it gets for gaming.

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Post by spitex » Wed 17 Nov, 2010 5:00 pm

ADSL Filtering Details

This is an actual email we've sent to our customers regarding ADSL Filtering and which ones to buy.

Estimated Line Length: 2.3 kilometres – Cisco 877
DSL Operating Mode Downstream BW Upstream BW
G.DMT (ADSL1) 8,128 Kbit/s 1024 Kbit/s
ADSL2+ 19,535 Kbit/s 1020 Kbit/s

Results:

The service initially trained up at 17mbit/s using ADSL2+ however any incoming calls to the phone line would result in a disconnect of DSL sync. In order to stabilise the connection ADSL1 filters were installed on the service and the CPE set to force only ADSL1 negotiation. This stabilised the connection to some degree though some phone calls would still result in sync loss. Checking the phone lines, a cordless phone was unplugged and replaced with a Telstra touch phone.

With ADSL1 filters and a single standard telephone on the line, attenuation fluctuated between 37db and 40db.

Sourcing Telstra/Austel certified ADSL2+ filters we have successfully been able to decrease the attenuation level to 27db. This has increased the stability of the service and also allowed an additional 2mbit/s to be negotiated on sync. This includes using the previous cordless phone, which are generally notorious for causing additional line noise. These statistics roughly translate to a near perfect signal for the line distance specified.

Rough calculations can indicate line length in Kilometres by dividing the DSL attenuation level by 13. In this instance, by using proper certified filters we reduced the effective line distance by 1km.

The inline ADSL2 filters certified and used were ACS – Model 901E2+ - http://www.advancedcircuits.com.au/

For the test, we sourced the filters from Warcom – Click to View.

It is obvious that with ADSL2 services circuits are extremely sensitive to noise and sync problems. For this reason we suggest that more than ever proper filtering is considered when installing CPE at customer sites.


You can also get these filters from Queensland Cables and Connectors @ Milton.

http://www.qconnect.com.au/

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Post by cGr » Wed 17 Nov, 2010 5:16 pm

Friggin awesome info. I love having all this info in one spot!

In real world terms, what sort of figures are you talking between a mid-range modem and the cisco? 10%? 20%? 5%?

I'd love a draytek 2820vn (to replace my $100 netgear voip thingy which is probably similar in spec to woody's belkin), but to fork out $400 is a big ask, especially when I'm not really getting a big improvement in modem speed.

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Post by woody2 » Wed 17 Nov, 2010 10:29 pm

Jeez... Glad I asked that question then...

Looks like I have some research to do.

Big thanks Spitacus.

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Post by German » Thu 18 Nov, 2010 8:38 am

Currently looking at billion, draytek and cisco models.

That iptrading site is a bitch to use. :lol:

What you using at home ry?

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Post by dan » Thu 18 Nov, 2010 8:57 am

spite wrote:* ADSL Tips - if your ISP Supports it (most do), use ATM PPPoA/VCMUX for the ADSL and ATM framing protocol. Never ever use PPPoE unless you have to. Most people have PPPoE/LLC setup - this is wrong.


i tried this with my optus/exetel naked adsl2+ connection last night and i couldn't get it to work :( i didn't spend ages playing with it tho, will try to fiddle another time and see if i can convince it that this is a good idea.
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Post by blv » Thu 18 Nov, 2010 9:12 am

dan wrote:
spite wrote:* ADSL Tips - if your ISP Supports it (most do), use ATM PPPoA/VCMUX for the ADSL and ATM framing protocol. Never ever use PPPoE unless you have to. Most people have PPPoE/LLC setup - this is wrong.


i tried this with my optus/exetel naked adsl2+ connection last night and i couldn't get it to work :( i didn't spend ages playing with it tho, will try to fiddle another time and see if i can convince it that this is a good idea.


same, my net doesnt work unless the modem is set on PPPoE/LLC

Is there any other settings to change other than changing to PPPoA/VCMUX? or could it be something TPG would have to adjust their end?
I just don't know if people like me. I know when they don't like me 'cause they'll say things like, 'Yeah, that's him, officer.'

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Post by German » Thu 18 Nov, 2010 10:17 am

Cheapest places to buy billion or draytek?

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Post by cGr » Thu 18 Nov, 2010 10:38 am


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Post by German » Thu 18 Nov, 2010 11:04 am

Billion it is then and msy as well.. :lol:

Harris Technology want $258 while msy only want $158..

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Post by spitex » Thu 18 Nov, 2010 11:08 am

German wrote:Currently looking at billion, draytek and cisco models.

That iptrading site is a bitch to use. :lol:

What you using at home ry?


Cisco 877W Advanced IP Services (you don't need that software set, I just do for work).

dan wrote:i tried this with my optus/exetel naked adsl2+ connection last night and i couldn't get it to work :( i didn't spend ages playing with it tho, will try to fiddle another time and see if i can convince it that this is a good idea.


Some ISP's wont support it. It really depends on their exchange DSLAM platforms and DSLAM to POP/LNS Backhaul types. The reason you preference PPPoA is the following.

DSL technology uses the ATM platform. ATM is a technology type that was typically used for higher optical connectivity type - 34mbit T3 -155mbit/s OC3. ATM technology scales to THOUSANDS of Megabits/s and is still one of the most used undersea and interstate longhaul technology and connectivity types. ISPs use ATM on the Customer to DSLAM connection and then traditionally on the ATM interconnect to get from exchanges in your Suburbs to their major POPS or (Points of Presence/Aggregation/Interconnect).

Ethernet is much lower cost, and the majority of new DSLAM providers now backhaul using Ethernet. It's the same piece of optical fibre but instead of the transmitters on each end costing 10k and being 155mbit, they cost $1k and are 1Gbit/s.

All that aside, your DSL router/modem at your home uses ATM protocols to talk to the actual DSLAM equipment. On top of this is your PPP session (username and password) which authenticates you to the ISP network and provides IP traffic.

PPPoA (PPP over ATM) natively runs on DSL and allows full 1500byte MTU (maximum transmission unit).
PPPoE (PPP over Ethernet) requires a ethernet bridging layer to be applied to the ATM interface which reduces the max payload size to below the normal ethernet standard.

What this means is typically packets sent from your computer 1500bytes in size travel over the PPPoA uninhibited and forwarded onto the ISP network and then out to the net.

When using PPPoE your packets get to your router and the router will do a couple of things. It will tell your PC to only transit SMALLER packets 1460ish bytes and request you retransmit OR it will FRAGMENT the packet splitting the 1500byte packet into two smaller ones, thus increasing the BURN on your router's CPU.

Routers throughput or performance is based on PACKETS PER SECOND and not KBYTES/S. A router receiving 100packets that are 1byte long is doing as much work as another router doing 100 packets that are 1500bytes long. That's a bandwidth difference of 100byte/s and 150kbyte/s.

So the long and short is ... PPPoE makes your router work harder by having to pass more packets, fragment larger ones which require processing or tells your computer to send non-regular ethernet frames.

For general internet it makes no difference. Download speed and latency performance will be affected ever so slightly but not noticable. Anyone downloading/sending alot PPPoA is better.

For some ISPs you have no options. It's a limitation of their backhaul and termination equipment.

PPP Authentication types have ABSOLUTELY NO BEARING on your sync speeds.

Whirlpool Explanation
PPPoE or PPPoA?
Point-to-Point Protocol over ATM (PPPoA) and Point-to-Point Protocol over Ethernet (PPPoE) are two alternative protocols for connecting to your ISP. Some ISPs only support one or the other, but many support both. Additionally, some PCI-based ADSL modems only support PPPoA.

PPPoA is ever so slightly faster than PPPoE as PPPoA has 8 fewer bytes of overhead in every 1500 byte packet. Most users do not notice the difference which works out to be about one-half of one percent.

Using PPPoA does avoid the Maximum Transfer Unit (MTU) issue. The effect of mismatched MTUs is that random web pages may not load fully, file transfers and email downloads may also appear to freeze. The MTU for PPPoA is 1500 bytes, whereas the MTU for PPPoE is 1492 bytes due to the 8 byte overhead which this protocol incurs. On MS Windows PC(s), the solution for PPPoE MTU issues is usually to lower the MTU on the network interface card (NIC) using one of the various utilities such as DrTcp.

Note: VPN tunnels also add extra protocol overheads of between 24 and 57 bytes to the MTU. An IPsec tunnel over a PPPoE connection may need an MTU as low as 1435 bytes. A low MTU value will always solve an MTU issue, but the lower the MTU, the lower the data throughput of the link will be.

The gory technical details are dealt with here complete with fixes for Solaris 8 (and earlier), HP-UX 9/10/11 and MS Windows 95/98/ME/NT/2K/XP. For MS Windows clients behind FreeBSD gateways, see here (Recent versions FreeBSD's user PPP software automatically fix this problem).
Last edited by spitex on Thu 18 Nov, 2010 1:03 pm, edited 4 times in total.

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Post by spitex » Thu 18 Nov, 2010 11:18 am

German wrote:Billion it is then and msy as well.. :lol:

Harris Technology want $258 while msy only want $158..


Checkout http://forums.whirlpool.net.au/forum/82 for information about routers/ADSL etc. Get what's popular, and people are happy with.

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Post by spitex » Thu 18 Nov, 2010 11:22 am

PS. I realise I am bombing this thread with nerdspeak, but I figure if you understand the reasoning it might make a little more sense ;).

If something is unclear, ask and I will try and answer.

Sorry if you don't care, just don't read this thread :P

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Post by SecaBoy » Thu 18 Nov, 2010 11:41 am

and here i am thinking you're just a good looking guy... :D
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Post by cGr » Thu 18 Nov, 2010 11:42 am

spite = :metalasfuck

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Post by blv » Thu 18 Nov, 2010 11:46 am

I think its great. Plese dont stop.
I just don't know if people like me. I know when they don't like me 'cause they'll say things like, 'Yeah, that's him, officer.'

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Post by German » Thu 18 Nov, 2010 11:54 am

I zoned out couple times and starting watch you panda rolling around then kept reading. :lol:

7800N could be the goer..

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