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The fastest, most reliable internet connections on the market.

Leased Lines

Your leased line should be Intelligent, Resilient, Agile.

The sector:
The challenge:
increased resilience and bandwidth, along with traffic prioritisation, to support business critical services.
The sector:
The challenge:
improved internet connectivity to meet staff and pupils’ downloading requirements.
The sector:
The challenge:
increased bandwidth and resilience at all sites. A managed WAN linking all sites. And more.

Bonded ADSL is where multiple ADSL lines are joined together. There are three distinct processes:

  1. Data is split up, at the packet level, into separate streams.
  2. Those streams are sent simultaneously over the multiple ADSL lines in the bonded connection.
  3. The data is recombined into its original form before being sent on to the Internet or another node on the same network.

This process operates in both directions – upstream and downstream.

How does Bonded ADSL work?

Bonded ADSL vs Traditional ADSL

A traditional ADSL connection is set up by connecting an ADSL modem to a broadband-enabled BT phone line. To share this connection across the network, a router or firewall device sits between the modem and the network. This is how most single line connections work.

Bonding two or more ADSL lines together involves installing additional broadband-enabled phone lines and an on-site device – a bonder – to do the bonding work.

Each line in the bonded connection has its own modem. All the modems are connected to the bonder. The bonder, coupled with a carrier-grade ISP server, hides the multiple lines from the local network, acting as a “default gateway”. In the traditional, single line setup described above, this role is fulfilled by the ADSL modem. The firewall has an IP address, or a block of them, and sends all its internet requests to the bonder, through a single ethernet cable.

A single connection with multiple lines

Data sent from the local network is split up and distributed over multiple internet connections by the bonder. The data is reconstructed into a single stream for transmission to the Internet, by a central bonding server in the ISP’s network.

The process is bidirectional, operating on both upstream and downstream communications.

The local bonder and the central bonding server hide the multiple lines from both the local network and the Internet, allowing the customer’s devices to send and receive data exactly as they would over a single ADSL connection, but with the benefit of much enhanced bandwidth and uptime.

A single connection with multiple lines
What happens when a line fails?

What happens when a line fails?

The on-site bonder and the ISP’s central bonder constantly monitor the lines with tiny packets of data. When they detect a problem with a line, they stop the traffic flow on that line while continuing to pass traffic on the others, making the line failure completely transparent to users.

Clearly the failed line must be restored as soon as possible, so for this to work effectively, it is essential to select a provider who will closely monitor all lines in the bonded connection and work closely with BT when faults arise.

With constant, high quality monitoring, many faults can be resolved without the customer even knowing about them. Others may genuinely be issues on the customer’s network – power outages, for example. Effective monitoring ensures the customer is made aware of such issues without delay.

Load balancing?

While they are sometimes confused, bonding and load balancing are very different.

In an ADSL load balancing setup, each individual data session is allocated to a single ADSL line. Each line has its own IP address, making hosting and resiliency near impossible, and this setup will never match the speed capability of an equivalent Bonded ADSL connection.

With a unique IP address for each ADSL line, no user will ever be able to use more bandwidth than that delivered by a single line, and should a line go down, its IP address and any traffic using it are lost in their entirety.

Load balancing?
IP addressing

IP addressing

A genuine Bonded ADSL connection gives extensive IP flexibility, allowing the connection to be tailored closely to business requirements. Fully routed IPs, NAT IPs and private IPs are all available, in any combination.

For example, if a customer has a VPN, requiring a fully routed IP on the firewall, and also a WiFi network which needs internet access, but which should not infringe on WAN security, the fully routed IP can be delivered alongside a private IP range for the WiFi router, both connected to the bonder, sharing the same Bonded ADSL connection.

Alternatively, a small business may have a traditional setup with a mail server, an intranet and other web facilities for staff, an FTP server and Citrix or other Remote Desktop services. With a public routed NAT IP, all this traffic can be handled by a single IP connection, yet forwarded to the correct servers through the firewall.

Bonding hardware

Hardware requirements vary widely between providers, depending greatly on whether or not customers manage their own broadband circuits. Each circuit terminates on a device (a modem, in the case of ADSL, ADSL 2+ and FTTC) which requires cabinet space, power and cooling.

Each modem is plugged into a bonder, acting as the default gateway for the router/firewall to access the internet. Some providers, instead of using a single, dedicated bonding device, prefer a master/slave arrangement using integrated modem/router devices. These are usually consumer-grade devices with adapted firmware. This configuration lacks a single ethernet port to connect, so requires an additional switch, which of course also needs space, power and cooling.

Some providers also place limits on the throughput handled by individual devices, requiring, even on a mediocre connection, further additional hardware units, each line using a modem, router and switch. For a 4x Bonded ADSL connection this would mean nine devices, all requiring space, power, cooling and interconnecting cables, before the firewall.

To find out more Bonded ADSL and the benefits it could offer your business, call 0330 55 55 333 or email us today.

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