Rapid IP Rerouting with SDN and NFV

Abstract

Current Content Delivery Networks (CDNs) primarily utilize the Domain Name System (DNS) to direct users towards optimal content replica servers. Typically, these CDNs will leverage specialized DNS servers to perform load balancing, by providing different users with different IP endpoints for a particular hostname. However, there typically exists some form of DNS cache between the user and the authoritative DNS for a particular web service (Examples include web browsers, operating systems, and home routers). While these DNS caches typically improve user experience and network performance by reducing the number of redundant DNS requests, there exist scenarios where the presence of a DNS cache can actually harm network performance and user experience. For example: if a server or datacentre were to suddenly become unavailable, end users may become `stuck' trying to access the old IP address contained in their DNS caches, even though the authoritative DNS server may have updated it's records accordingly. In order to address this issue, we propose a system that enables network operators to transparently redirect users towards optimal servers during times of network congestion or high server load. By leveraging SDN and NFV, we are able to implement this system over a variety of network infrastructures, and to various levels of scale. Our initial tests indicate that our methodology has the capability to vastly improve user experience by several orders of magnitude during times of high network load, over a variety of network conditions. Our system is application- layer agnostic, and is compatible with various networking protocols.