SDN changes the development path of router technology

Over the past 30 years, IP networks with routers and switches as the core have always followed Moore's Law and built modern information civilization together with other IT equipment. Among them, routers, as the core equipment for WAN and LAN exports, have always played a key role and have also experienced continuous development and countless upgrades.

Today, router interfaces have changed from a variety of narrowband interfaces such as X.25, E1, ATM, POS, SDH, etc. to broadband pure Ethernet interfaces, supplemented by a small number of higher-speed and higher-performance wavelength division interfaces; in terms of operating protocols, they have gradually unified into a distributed IP/MPLS system. Larger bandwidth, lower latency, smaller size, and better cost make routers and their "brother" switches and PTNs the basis of almost all networks.

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However, change and movement are eternal, and development is the hard truth. Currently, driven by 100M broadband access, 4K online video, 4G/4.5G/5G, the Internet of Everything, as well as the customer experience first and SDN/NFV trends, routers are also facing continuous evolution and change.

First of all, the wide-area IPWAN network formed by routers is a network with a very wide range of applications. Generally, the cost of building a new network is very high, so a large part of the demand is to expand network capacity, which requires a certain degree of compatibility in technology. Therefore, the basic trajectory of router development and the focus of competition are still the evolution of a reasonable speed. On the basis of inheriting historical functions, continuous improvement in capacity and capabilities should be achieved. Taking core routers as an example, the mainstream equipment that can be commercially used currently has 16 to 20 slots per system, 400G per board, and a single subrack system of 6.4T to 8T. The subsequent development and competition point is to launch 1T, 2T, and 4T boards at the right time, and it is best to be compatible, with increased capacity, and no increase in power consumption and price, to continue to meet the requirements of Moore's Law.

Secondly, smaller size. Traditional mid-to-high-end routers are all bulky "iron lumps". As property costs increase year by year, "small size and large bandwidth" routers that take up less space are becoming popular. For some base station site routers, customers even want outdoor models that can be directly mounted on poles. Under this trend, it is very important to study the miniaturization or outdoorization of routers. If it can be done well, the product will be very popular and can also form a number of differentiated competitive advantages.

The last point is to focus on customer experience. In terms of hardware composition, Xiaomi routers use common components, but in terms of software, it has created a set of App-based application chains, which are not only convenient to use and create new value, but also can drive more sales of Xiaomi smart homes.

With the development of SDN/NFV, the router-centric solution is gradually undergoing a transformation. The basic point of the transformation is the introduction of SDN (Software Defined Network). IP networks can be widely deployed around the world thanks to a distributed protocol system. Even if the routers of one or more nodes crash, the IP network can still continue to operate, which is very remarkable. However, it is this distributed system that makes it difficult to implement many global special strategies that would have been easy. The "IQ" of IP networks is actually very low. What's more troublesome is that there is a gap between the application layer software and the router software in the control of the network, making it difficult to implement application strategies fully automatically. The introduction of SDN is trying to solve these problems.

Of course, in the wide area network composed of routers, one move affects the whole body, so the introduction strategy of SDN is relatively conservative. Conservative means trying not to touch the forwarding plane of the router, and trying to maintain compatibility on the control plane. In a hybrid system operation mode, the control plane running on the router is gradually transferred to the centralized operation on the controller, and through the hierarchical controller and reasonable northbound interface, the demand for full software automation is realized. The original interface, such as NETCONF or even CLI, or the extension of the original protocol such as BGP-LS and PCEP, is used between the controller and the device. The original concepts of PW, L3VPN, MPLS TE tunnel, etc. on the router are still retained, but the operation mode has changed. The original "low intelligence" situation has been greatly improved by the introduction of SDN.