ADSL Bonding – How To and Review
Submission by Paul Gale – In the desire to increase my upstream speeds as much as possible I did some research into ADSL bonding or MLPPP (Multi Link Pont to Point Protocol). A handful of ISP’s offer support for this (they tend to be smaller companies though rather than the likes of BT, Yahoo etc). After a fair bit of hunting around and talking to people, I plumped for 3 x ADSL Max Premium (Office) connections from a reseller, UKFSN (www.ukfsn.org), of an ISP called Enta Net (www.enta.net).
Each of the three lines would provide me with up to 8Mbps downstream and 832Kbps upstream (the home or standard product gives 448Kbps upstream). The Premium or Office product supposedly gives higher priority to your traffic in BT’s network along with the higher upstream speeds. Contention ratios are no longer used to differentiate the products on BT’s IPStream network that Max uses. Each of these lines would be bonded together using MLPPP -“ both at the ISP and at my end using a Linux based self-built PC router and using free software from FreeStuffJunction (http://www.freestuffjunction.co.uk/). Each connection is plugged into a Sangoma S518 PCI ADSL modem (one for each connection), costing £112 each.
The router boots and runs from CD ROM or a write-protected USB pen drive, increasing security. In my case, my old main board didn’t support booting from USB pen drive so I used a hybrid solution of a boot loader from CD which then hands over to the main o/s held on the pen drive. Configuration files for the connections and services such as IPTables, the Linux firewall etc are held on a second pen drive. The router software is fully featured and supports IPSec VPN, NAT, Firewall, Squid proxy cache, traffic shaping, DHCP, Snort intrusion detection and SNMP amongst others.
Setup and configuration of the router was really simple. The whole package is supplied as an .ISO image and you simply have to set a few configuration options which take the form of a number of text files (Just the existence of the file sets the option in most cases). Once up and running, the router is managed by a modified version of Webmin, the Linux web based admin system. In-depth knowledge of linux is not needed unless you really want to get ‘under the hood’. Once all lines have been brought up and bonded, there are a number of reporting and information options available from Webmin. The software also runs a script, checking on the status of the lines and re-bonding if one should fail. So far, over the couple of months the router has been running, I’ve not had any problems. Support from the developer and fellow users is available free via a forum and an expensive premium rate phone number if you can’t wait for a reply via the forum.
The router works on any old 486 and up PC you might have lying around. You need to ensure it has enough PCI slots to accommodate the PCI ADSL cards though. The router also supports bonded SDSL but requires a different card type for this.
So what was I expecting from this solution? The maximum theoretical downstream rate in my case is 24Mbps and upstream 2.5Mbps (approx). Of course, this is the sync speed – data throughput rates will be less due to IP overheads etc.
To get the three ADSL lines into my office, I had to migrate one existing 2Mbps service from Eclipse, convert a Home Highway line to analogue and get a third analogue line installed – quite a job – and, you guessed it, none of it went smoothly! Most problems were caused by BT failures or problems, both with their ordering systems and various other technical problems, including not having enough lines available in my road. These problems overall took a couple of months to resolve.
Being a reasonably early adopter of ADSL Max, I also suffered from a number of different ‘teething’ problems. One such problem was caused by the BT network setting all three of my connections to the old 2Mbps throughput rate although the sync speeds were good at 8Mbps. This took a few weeks for support to find out what was going on and resolve. Another problem was caused by the sync rate of one of my lines being set to 6-6.5Mbps due to an earlier line fault during the initial 10 day period (It’s actually the target SNR ratio that’s set – the modem then sets the best speed it can with this SNR target figure). Apparently a BT insider says that the DSLAM (the piece of equipment in the exchange that links many ADSL subscribers to a single high speed ATM line) will eventually set this rate higher but will take several weeks or more to do so (the actual figures and details on how this happens have not been made public as the whole process is going through the patent process apparently). I finally managed to get BT, through Enta support, to manually set this target SNR back to what it should be (lower is better in this case – well, at least to enable high speed syncs) – the line has been syncing at 8Mbps happily since 🙂 It really does pay to keep pushing a resistant support person when you KNOW there’s still a problem!
So anyway, after all these problems, I now have a working ADSL Max MLPP bonded solution – but how’s the performance?
Well, upstream (and my original reason to install this lot was to increase this), I’m getting a steady 2Mbps (250KBps ish) – excellent – just what I wanted so I can upload large files via FTP for my customers quickly 🙂
Downstream is a different matter though and a little disappointing. I get anywhere from 3 to 6.5Mbps depending on the time of day. I’ve tested the throughput of individual lines as well as the 3 line MLPP bond. Sometimes, the 3 line bond performs at the same speed as a single line and at other times, it’s slightly higher – but never as high as I might have hoped for. This is still work-in-progress and I’m continuing to talk to Enta support and the reseller (UKFSN) to see if we can find out why the performance isn’t as expected, still, I’m very happy with the upstream performance which was my main reason for doing this and downstream isn’t exactly slow!
Note: these figures are actual THROUGHPUT data rates and were measured regularly by a number of methods including the ADSL Guide speed test and real world FTP transfers to several hosted web sites.
So how about costs? Well, the rough breakdown is as follows:
3 x analogue BT line rental – £11 per line per month (not sure yet if the second and third are charged at £12 or not) + VAT?
3 x Office Max ADSL Max lines (45Gb peak cap each and 300Gb each off-peak) – £25 per month + VAT
Migration of existing line – free
Conversion of Home Highway to Analogue – £50 (IIRC) + VAT?
New line – £99 + VAT?
PC to run router – free (as it was an old machine)
3 x Sangoma S518 ADSL PCI cards – £112 each (no VAT) – includes licence for the bonded router software.
128Mb USB pen drive with write protect switch – £30 (ish)
Note: that although the bonded router software is free, you need a licence for each ADSL PCI card you want to use with it. It is also available from other sources for free but may be an older version. The software is based on GPL software with a high level of customisation/scripts etc.
As I was previously paying £65 + VAT per month for a 2Mbps connection and a fair bit for a Home Highway line, implementing this solution hasn’t cost me a great deal more per month (if you take up front costs out), especially as I’ve gained so much more performance wise.
I hope this has been useful – overall, if you need as much upstream bandwidth as possible, I’d recommend this solution. It’s not for the faint of heart though as there are potentially many problems to be encountered. Hopefully, many of these will not occur though as ADSL Max becomes a more robust and understood product.
Paul Gale can be contacted on – adsl at siliconpixel dot com