Lessons from building an ISP at iBurst

Ronald Bartels
Jun 2 · 3 min read

iBurst was the original mobile data, done right. Invented by the same guy who created GSM. It was a 3G type technology. But iBurst went titsup! iBurst entered the South African broadband market when the best ADSL speeds available from Telkom were 512 kb/s. iBurst was able to provide a 1 Mb/s wireless service. It by default had higher throughput and was available immediately without a cumbersome installation process. It eventually reached a significant subscriber base of just over 50000 subscribers. Below is moi explaining some of it!

Below you can read an overview of the iBurst technology…

And over at youtube there is a video available as well…

The iBurst modem would connect to base stations and the sessions would all be terminated in a Cisco 7600 with MWAMs. This hardware was configured as Packet Data Serving Nodes (PDSNs). The features of this solution are provided here.

One of the configurations possible was to extend the termination from the PDSN to another ISP using L2TP. This is an excellent configuration and not one used by the largest provider of ADSL and FTTH in our neck of the woods called Openserve, previously part of Telkom. What Openserve does is to statically configure every ISP on its network with an overlay network using public IPs provided by the ISPs. This the the largest waste of IPs that are in short supply and is a direct result of the operator’s inability to implement a more efficient solution. The whole ADSL and FTTH network can be build on private network IP addresses (RFC 1918) and the ISP can effectively start utilizing this with a public IP address range as small as /29. The client connects using PPPoE and this session is then encapsulated within L2TP to the ISPs home network. Simple, millions of IPs saved for re-use.

L2TP has been around of ages and is the defacto standard for VPNs or all operating systems including Windows, Linux and MacOS. It is bullet proof and is often combined with IPSEC for encryption. I describe how to build such a system here. It is actually one of my most popular stories on medium.

At iBurst we build a secondary network using carrier Ethernet that was used mainly by business and most often using wireless CPEs at sub 6 Ghz. But there is an easy way to do it using L2TPv3. this allows the encapsulation of VLANs or Ethernet across an IP network.

Here is an interesting podcast over at the Network Collective about the history of pseudowires.

The Technology Burrow

The clan of braaivleis, rugby, sunny skies and computers.

Ronald Bartels

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Ronald is a technologist and service management evangelist. He started driving a tractor when he was five years old and would love to own a Massey-Fergurson!

The Technology Burrow

The clan of braaivleis, rugby, sunny skies and computers.