Ternary Content Addressable Memory (TCAM) is a specialized high-speed memory that enables fast parallel lookups for both exact-match rules and wildcard-match rules. TCAM has become a standard hardware component in Software-Defined Networking (SDN) switches to implement flow tables for packet classification. However, limited TCAM storage capacity poses a significant scalability challenge for SDN to enforce fine-grained policy-based forwarding. To this end, TCAM-based rule-caching systems are proposed by combining TCAM with Random Access Memory (RAM). Specifically, TCAM caches heavy-hitting rules to capture packets from hot flows, while RAM accommodates the complete ruleset for other cache-miss packets. However, previous rule-caching systems either failed to eliminate cross-rule dependencies or restricted their applications to prefix rules only. In this work, we propose AWEsome-Cache, a unifying framework to fundamentally eliminate cross-rule dependencies for wildcard rules with arbitrary matching patterns. The rationale behind AWEsome-Cache is to concretize a minimum number of wildcard bits in the best-match rule, thereby pruning its overlapping match fields with all direct dependent rules. AWEsome-Cache also develops replacement algorithms during TCAM updates to adapt to dynamic traffic locality. Experiments with prefix and non-prefix rules show that AWEsome-Cache outperforms baselines in achieving a comparable cache-hit rate but requiring 75.9% less TCAM occupancy.

RPCs are fundamental to our large-scale distributed system. From a security perspective, the blast radius of RPCs is worryingly big since each RPC often interacts with tens of internal system components. Thus, discovering RPC vulnerabilities is often a top priority in the software quality assurance process for production systems. In this paper, we present the design, implementation, and deployment experiences of PAIR, a fully automated system for privilege-escalation vulnerability discovery in Ant Group's large-scale RPC system. The design of PAIR centers around the live replay design principle where the vulnerability discovery is driven by the live RPC requests collected from production, rather than relying on any engineered testing requests. This ensures that PAIR is able to provide complete coverage to our production RPC requests in a privacy-preserving manner, despite the manifest of scale (billions of daily requests), complexity (hundreds of system-services involved) and heterogeneity (RPC protocols are highly customized). However, the live replay design principle is not a panacea. We made a couple of critical design decisions (and addressed their corresponding challenges) along the way to realize the principle in production. First, to avoid inspecting the responses of user-facing RPCs (due to privacy concerns), PAIR designs a universal and privacy-preserving mechanism, via profiling the end-to-end system invocation, to represent the RPC handling logic. Second, to ensure that PAIR provides proactive defense (rather than reactive defense that is often limited by known vulnerabilities), PAIR designs an empirical vulnerability labeling mechanism to effectively identify a group of potentially insecure RPCs while safely excluding other RPCs. During the course of three-year production development, PAIR in total helped locate 133 truly insecure RPCs, from billions of requests, while maintaining a zero false negative rate per our production observations.

Erasure-coded redundancy is a fault-tolerant method with low-cost storage overhead. It only stores data fragments and parity fragments rather than full data across the cluster. The write process of erasure-coded data can be asynchronous or synchronous. For synchronous write process, data are encoded when written to servers. The common method doing the process needs to confirm that each coded-fragment of the data is stored in a different server to maintain the best fault tolerance. This method underperforms in terms of availability, and also fails to achieve good performance because any failure of servers will shortly disturb the write process. Some consensus protocols such as RS- Paxos and CRaft, which are based on Paxos and Raft, can solve above problems by providing fault-tolerant ability for systems. However, RS-Paxos cannot achieve the same liveness as Paxos. CRaft still adopts full data redundancy to keep the same liveness as Raft when there are not enough healthy servers. Therefore, to solve the availability problem during synchronous erasure-coded data write process, we present a novel protocol ECRaft based on Raft. It always uses erasure-coded redundancy when the ratio of erasure-coded data fragments to parity fragments is bigger than 1. It also can reach the same liveness as Raft. With state machine purge, storage redundancy can be reduced to the extent that typical erasure-coded storage systems can achieve. We build a key-value store based on ECRaft to evaluate it. In our experiments, compared with CRaft using complete-entry replication, ECRaft can save 63 % of storage, increase write throughput by 28.2 %, and reduce write latency by 19 %.

Information-Centric Networking (ICN) is proposed to address the inefficiency of content delivery of IP networks from the perspective of architecture. In contrast, Content Delivery Network (CDN) is an overlay solution in current IP networks. We believe that even though ICN is fully deployed, there is still a role for CDNs to play in ICN networks. Since ISPs in ICN will replicate and forward contents according to their policies and interests, it may not align with the objectives of Content Providers (CPs). Therefore, CPs are willing pay a third party (i.e., CDN providers) a certain fee to meet their own requirements. In this paper, we propose to use the inventory model of Supply Chain Management (SCM) in logistics to formulate the content delivery process of ICN networks. The product-centric model of SCM is well-suited for the content-centric content delivery process of ICN networks. Also, we propose the system framework of inventory Centric Delivery Network (iCDN). Simulation results show that the average cost and link usage of the SCM-based algorithm can be reduced by 52% and 15% respectively compared to the baseline approach.

Satellite networks are drawing more and more attention, since they can provide various services to everywhere on the earth. Communication devices in satellites are typically powered by solar panels and battery cells, which are carefully designed to guarantee power supply and avoid deficiency. However, we find that unrestrained use of energy will cause a satellite to age quickly, because the number of recharge/discharge of battery cells is limited. Due to the extremely high cost of satellites, the development of energy-efficient satellite routing to save energy and prolong satellite lifetimes has become significantly important. In this paper, we do comprehensive studies. First, we model the power consumption of a space router, power supply by solar panels, and aging of battery cells formally. Second, we define the energy-efficient satellite routing (EESR) problem, and prove that the EESR problem is NP-hard. Then, we develop three algorithms to gradually solve the EESR problem. GreenSR-B is a baseline algorithm which computes link costs iteratively to compute a routing that minimizes the total recharge/discharge cycle number. GreenSR-A selects space routers to switch into sleep mode to improve energy conservation. GreenSR jointly considers energy efficiency and QoS requirements of path length and the maximum link utilization ratio. We evaluate our algorithms by simulations on a low earth orbit satellite network with real Internet usage traces. The results show that GreenSR can prolong the lifetime of satellite battery cells by more than 40%, with little increment in path length and a small link utilization ratio.

In the current IP networks, content replication and inter-domain Traffic Engineering (TE) are manipulated by different entities with respective objectives, and work at different layers as well. In Information-Centric Networking (ICN), however, they can both be administered by Internet Service Providers (ISPs) and work at the same network layer. In this paper, we present our study of jointly optimizing content replication and inter-domain TE in ICN, which aims at maximizing the profit of inter-domain traffic for an ISP while constrained by the limits of link bandwidth and the availability of contents. Results show that our algorithms can increase the ISP's profit by 66% and reduce the link utilization by 23% on average, which are near-optimal and with much less running time.

Information-Centric Networking (ICN) has been proposed recently to improve the efficiency of content delivery in current IP networks. ICN employs data names, instead of host addresses, as routing and forwarding indicators. Content in the ICN carries only signature of the content provider but does not contain the identity of the content consumer by default. Such information is, however, essential for many of the web applications, such as email, online social networking, online game, e-commerce, and other session-based web services. In this paper, we propose a session-based access control (SAC) mechanism for ICN scenario to bridge the gap. Key distribution protocols are designed to protect the confidentiality of the content during information delivery. We also employ a dynamic naming scheme to enhance user privacy. According to security analysis, our access control mechanism can provide communication security and privacy protection for both sides of the session. Our design can be easily applied to session-based applications in ICN with negligible overhead.

Information centric networking is proposed to deal with the inefficiency of content distributions in traditional networks. It replaces the current host-centric communication paradigm with the content-centric one, so all the network devices can identify and cache the contents passed by. Traditional cache consistency approaches which rely on the origin server to validate cached contents will not be practical in ICN. The origin server might be overwhelmed by the large volume of validation requests from ubiquitous caches. In this paper, we propose a cache consistency architecture named Content Update Validation System (CUVS). It makes use of the servers located in each domain to provide the content validation service. It relieves the origin server and the routing protocols from caring about the cache consistency issue. The system is designed as a hierarchical overlay network in ICN, so it is easy to deploy and scales well.

Transmission efficiency of the current Internet routing system has witnessed a continuous degradation with the increasing popularity of content-oriented applications (e.g., YouTube). As a future Internet architecture, Information-Centric Networking (ICN) is proposed to solve this problem partly by in-network caching which means ICN routers are aware of and able to cache the content being delivered. In this paper, we present a Hop-based Probabilistic Caching (HPC) for ICN. When delivering the data back to the requester, each content router caches the data with a probability determined by the number of the hops between the responder and the router itself. First, we design an approach to computing the hop-based caching probability with a small amount of overhead. Second, we provide a caching weight based on the mean residence time of the cached contents, which guarantees that the cached contents remain in a router for an expected duration. The simulation results show that HPC achieves a caching hit ratio of 60% and extensively improves the transmission efficiency, compared with 20%, 43% and 46% of LRU, LFU and ProbCache, a recently proposed scheme for ICN, respectively.