Knowledge base Bonding lines
There are many ways to bond multiple lines together and there are different reasons for wanting to do this. The main reasons are extra overall speed, and added redundancy against failure.
Our broadband services allow use of multiple lines to provide both of these objectives. Our extra line service allows additional lines on the same login at the same site sharing the same tariff.
One of the key benefits of our service is that downlink bonding can be achieved with nothing more than multiple cheap ADSL routers on your network. There is no need for expensive multi-line ADSL routers.
Fast failover
It is important that when a line fails for any reason the service switches automatically to using the remaining lines. Our constant quality monitoring system means we are constantly monitoring every line and will be able to react to a failure of a line within 10 seconds. When a line goes out of service the routing of traffic can automatically switch to remaining lines.
When using multiple lines for redundancy this allows the fall-back line to come in to service very quickly. When being used for extra speed the failed line simple means less speed until the problem is resolved.
We provide email and text alerts of lines going off line unexpectedly so that you are alerted to the problem.
Faster speed (download)
To achieve a faster overall speed traffic sent from the internet to you can be sent using multiple lines. This is done by sending each packet down one of the lines in a load balanced way so that overall the traffic is balanced between the lines. The speed of the lines is taken in to account so that a slower line will be sent less traffic than a faster line. The packets then arrive at your routers at your end and arrive on your LAN.
The effect of this is that the two or more lines are used at ones an so even a single file transfer will be able to make use of all of the lines.
The only downside of this method is that sometimes packets can arrive in a slight different order to which they were sent. This is normal and part of the IP protocol. However, not all systems handle out of order packets as well as they could so the more lines you have the less effective the bonding is.
Faster speed (upload)
Like most ISPs we restrict what traffic can be sent to us so that it must be from one of your IP addresses. However, unlike most ISPs we are able to set up your IP addresses over your multiple lines. This allows you to send us traffic from any of your IP addresses via any of the lines on your site.
What this means is that you can do with uplink what we do with downlink - you can send packets up any of the lines and load balance them to achieve a higher uplink speed overall.
What this does mean is that you have to have equipment to do this.
FireBrick
A FireBrick can provide monitoring of your lines and routing of traffic up multiple lines. You would need the Bonding and Profiles features to achieve this. A FireBrick FB105 can manage around 10Mb/s throughput so this is ideal if your primary need for extra lines is uplink capacity. When available, the new FB2500 will provide up to 100Mb/s of routing to handle multiple lines.
Linux
A linux router can provide routing on per packet or per session for traffic to use multiple lines. You may need to make scripts to monitor lines to arrange for fall-back. We hope to have a more detailed knowledge base article on this soon - in the mean time we suggest you ask other customers on irc or usenet.
Simple fall-back
Most ADSL routers allow manual routes to be configured. This means you could configure and ADSL router to use a second router as its default route when its broadband link is down. Doing this means you can use one of your routers as a gateway, and it can automatically fall-back to the other if the line fails.
IP routing
Our control pages allow you to adjust the IP routing on your lines. You can have multiple IP addresses on a login, and each can be set for routing to one or more lines. You can set each IP address block separately.
Where routed to more than one line then traffic for those IPs is sent down multiple lines at once to achieve extra speed.
There is also a secondary routing set which is lines to use when all of the primary lines are not working. Commonly this is used with one line as primary and one as secondary but complex arrangements can be made. Secondary routes also control the allowed source IPs for uplink even when the primary lines are active.
You will normally have a WAN IP address for each line alone, and either a /30 for each line, or a /29 covering all lines (one address used as each routers LAN address). Often people will then have a block of addresses routed via all lines which each router sends to an internal router or firewall on your LAN.
You can have multiple address blocks. This means, for example, you could have one block primary to line 1 and secondary to line 2, and another block primary to line 2 and secondary to line 1. Maybe one for VoIP phones and one for normal PCs. Then if either line fails all traffic goes via the main line.
Tunnelled bonding
Another approach is to use a tunnelling system of some sort such as a VPN or FireBrick tunnels to tunnel traffic via one or more lines to a tunnel endpoint held in a data centre. We offer hosting services and host FireBricks as tunnel endpoints. We plan to offer high capacity FireBrick tunnel head end points for the FireBrick FB2500 when it is launched allowing multiple line tunnelled connections which can be via multiple ADSL lines that are even from different internet providers.
