By Deependra Malla, Cox Communication Inc.
The continuous advancement of IP networks marked by increased capacity requirements, increased network assets, and elevated customer expectations on service continuity and quality of service, has placed substantial demands on the network infrastructure of Multi-Service Operators (MSOs), Internet Service Providers (ISPs), and large enterprises. To help meet these demands and improve network performance, network operators have started adopting Segment Routing (SR) in the various parts of their networks - access, metro, and backbone. The evolution of access technology from cable Internet to Passive Optical Network (PON) involves a transition in the technology and architecture used to deliver high-speed broadband services to end-users. Both cable Internet and PON are broadband access technologies, but they differ significantly in their underlying infrastructure and methods of data delivery. The primary concept behind PON is to bring fiber optic cables directly to the end-users, eliminating the need for intermediate coaxial cables or copper lines. This is often referred to as Fiber-to-the-Home (FTTH) or Fiber-to-the-Premises (FTTP). Although cable access is Cox’s legacy access technology, it introduced FTTH to its customers in 2014 under the brand name “Gigablast”. Since then, Cox has continuously invested in network infrastructure and improving the quality of Gigablast services offered to its customers. Adoption of Segment Routing in the Cox’s PON aggregation and metro network is a crucial step towards making Cox’s access network more optimized, scalable, and resilient. As the networking landscape evolves, the industry is leaning towards more flexible and software-driven networking paradigms. So, transitioning to Segment Routing positions Cox metro network to embrace these future changes and innovations. Adopting the SR also helps Cox to provide improved network performance and service continuity to its customers. The Cox metro networks is an MPLS enabled network and runs LDP as the label switching protocol. LDP is used for following purposes in Cox metro networks: • Label switch BGP traffic, • Transport label for L2VPN, and • Transport label for L3VPN In the Cox metro network, Segment Routing is used to distribute MPLS labels and accomplish all the above services. Following are the motivations for enabling SR in Cox metro networks: • Protocol simplification and unified control plane • Achieving <50ms failover during link failure • Tactical traffic engineering capability • New protocol knowledge acquisition Since Segment Routing is a more recent approach to label switch traffic, it is not available in legacy hardware. Hence, during the initial phase of SR deployment in Cox, LDP and SR will co-exist. Wherever the SR is enabled along with the LDP, the SR is made a preferred label switching protocol.