Retrofitting Internet Exchange Points with Software Defined Networking

The roughly 300 Internet Exchange Points (IXPs) around the world perform an important role in directing web traffic via local exchanges and reducing communication delays.

Unfortunately, many emerging economies have few or no IXPs, meaning they have to direct web traffic through sub-optimal routes, lowering communication speeds and often compromising reliability. Sometimes, data is unnecessarily directed beyond national borders incurring expensive international transit fees.

IXPs are not so difficult to set up. All that is needed is a secure location to host it — usually this is a data centre that is easy to run fibre access lines to and offers 24/7 access to members, which typically are Internet Service Providers (ISPs), content providers (such as Facebook) and Content Distribution Networks (CDNs). One big challenge is in scaling the IXP, given that many are run voluntarily.

Apart from having more volunteers or paid staff to maintain an IXP, one option is to automate some of the day-to-day monitoring processes using Software Defined Networking (SDN).

SDN enables the network to be controlled and configured using software applications that are logically centralized. SDN can be deployed at an IXP to create what is normally termed a ‘Software Defined Internet Exchange Point.’ Retrofitting an existing IXP with SDN is challenging as it requires rearchitecting the software and may also need upgrades to the existing hardware.

Bringing SDN to emerging economies

Wanting to make SDN more accessible for smaller IXPs in emerging economies, a team from LUMS University has developed a method to conveniently retrofit IXPs with open source SDN applications.

Led by Zartash Afzal Uzmi, the team was able to retrofit an IXP in a lab setting, intended for deployment at a local IXP in the capital city of Islamabad, using their own prototype software package.

“There were two main drivers that prompted this project: first, the huge popularity of the SDN technology and its flexibility to control network traffic for enterprise and wide area networks, by offering direct control over packet-processing rules that match on multiple header fields and perform a variety of actions,” says Zartash. “And second, we had a perfect example of a new and smaller IXP here in Pakistan to experiment with.”

The prototype software package they developed provides an IXP Manager — a web-based peering portal currently used by around 80 IXPs — with additional SDN capabilities added during the course of this project. Zartash says future plans are to develop and test the package at full-scale IXPs around the world.

“This would mean that rather than needing to create a software defined Internet exchange point from scratch, existing IXPs would be able to retrofit their current deployments to add SDN functionality with far less effort,” explains Zartash.

“This is an easy and economical way for them to set up a software defined IXP fabric as well as use novel applications that are only possible when the IXP deploys the SDN capability.”

“Technically, this solution would be suitable for all IXPs, though we have not had the opportunity to test the scalability of our implementation for large commercial deployments,” says Zartash.

“Very small-sized IXPs usually do not need novel applications offered by an SDN-based IXP and would enjoy only a marginal benefit. Medium sized IXPs, where scalability is less of an issue, would benefit more because they can easily add SDN capability to their existing IXP deployment based on our software and documentation. IXPs in developing economies, where there are fewer resources available, would definitely benefit the most from our project.”

The many benefits of an IXP with SDN

SDN can reduce the cost of running an IXP via automatic configuration management and dynamic policy assignment. These processes mean fewer staff are needed to run the system.

“It (the new IXP Manager) was developed to automate the peering process and the configuration of novel peering structures such as inbound traffic engineering, server load balancing, and application specific peering,” a report on the project notes.

Another key benefit of adding SDN capability to an IXP is that it allows more inter-ISP traffic data to be collected. This has potential to incentivise international cloud service providers to host their platforms in regions with SDN-capable IXPs.

“The knowledge of ‘where’ the traffic is destined and downloaded from will motivate additional local and international cloud service providers to get interested in hosting their platforms within the region,” says Zartash.

“This project will not only provide this platform to easily interconnect and manage ISPs but will also pave ways for global content and application service providers and content distribution networks to peer at the IXP,” the report notes. “This will be possible by having easy access to the inter-carrier traffic volumes observed at the IXP, easily measurable by the use of SDN.”

The team plan to make it open-source, to benefit the entire IXP community. However, the fine-grained details of real testbed experiments in collaboration with any particular IXP might not be open source due to privacy constraints for that IXP.

This research was supported through the APNIC Foundation’s ISIF Asia 2018 grants, under the Internet Operations Research Grant funded with an APNIC contribution. A USD 30,000 grant was awarded to LUMS university for this project.

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