Use Cases for Communicating End ‐ Points in Mobile Network Middleboxes

Gi Middleboxes are deployed in mobile networks on the Gi reference point which is where the 3GPP mobile network meets the Internet. They are essential in performing functions that regulate and manage traffic for better QoE but their role has not been devoid of controversy. The ongoing usage of end‐to‐end encryption significantly impacts the function of currently deployed middleboxes. For example, application detection via identification of signatures in traffic no longer works on encrypted traffic. Media trans‐rating and transparent content caching fail as well. Substrate Protocol for User Datagrams (SPUD) is a set of tools that enables endpoints (server, device) to safely communicate information about communications with each other and with middleboxes, without compromising privacy of content and under control of an opt‐in framework. This position paper discusses the role of cooperative information sharing frameworks, such as SPUD, in facilitating the deployment of middleboxes for their more lofty traffic management and flow regulation purposes while neutralizing some of the more controversial functions. We argue that cooperation in the eco‐system of content publishers, mobile network operators, and subscribers will result in a better mobile Internet experience and ultimately result in a radio‐friendly transport protocol that may supersede TCP. Introduction This position paper presents a viewpoint on addressing the architectural impact of data plane encryption on 3GPP mobile networks. The mechanism is one where end‐points (mobile device and origin servers or their proxies) exchange relevant and pertinent information about the path and the application withapplication with middleboxes (routers, base stations, packet core elements, optimization elements, and other in‐path elements). The framework discussed is cooperative in nature and based on an opt‐in model controlled by the 3GPP policy layer. We don’t expound on incentives for cooperation. These can be monetary (e.g. a network user such as a subscriber or content publisher buys a service) or barter‐based (a user permits or allows a capability in exchange for a benefit). At the time of writing, over 50% of mobile network traffic is encrypted on a per session basis using TLS or SSL [1]. The percentage by volume is expected to rise to near 100% with the deployment of HTTP/2 [2] consistent with the IAB recommendations [3] and the increasing ease of obtaining X.509 certificates [4]. The proper functioning of Gi middleboxes is compromised by encryption. Smith [5] and also Moriarty and Morton [6] have documented the impact in Internet Drafts. Most agree encryption is desirable and necessary to protect the privacy of user traffic as well Internet revenue models such as advertising that rely on content being delivered intact. Our position is that middleboxes play a useful role because they are deployed to address the harshness of the 3GPP radio environment. Radio bandwidth is neither plentiful nor cheap, and variability in the form of fades, shadowing, user mobility, handovers, etc. can constrict the channel at a moment’s notice. The use of encryption hides information which is used by network operators to provide network management and control functions that benefit overall quality of experience. Gi Middleboxes are deployed to optimize delivery of packets to subscribers. Some of these trans‐rate or compress the content reducing the volume of bytes delivered over the air interface. Others offer