Information-Centric Networking (ICN) is an internetworking paradigm that offers an alternative to the current IP-based Internet architecture. ICN's most distinguishing feature is its emphasis on information (content) instead of communication endpoints. One important open issue in ICN is whether negative acknowledgments (NACKs) at the network layer are useful for notifying downstream nodes about forwarding failures, or requests for incorrect or non-existent information. In benign settings, NACKs are beneficial for ICN architectures, such as CCNx and NDN, since they flush state in routers and notify consumers. In terms of security, NACKs seem useful as they can help mitigating so-called Interest Flooding attacks. However, as we show in this paper, network-layer NACKs also have some unpleasant security implications. We consider several types of NACKs and discuss their security design requirements and implications. We also demonstrate that providing secure NACKs triggers the threat of producer-bound flooding attacks. Although we discuss some potential countermeasures to these attacks, the main conclusion of this paper is that network-layer NACKs are best avoided, at least for security reasons.
The main objective of the MAC protocol in IEEE 802.11 standard is to access and control the shared limited bandwidth medium efficiently and fairly among all nodes. A maximum throughput is difficult to achieve due to the limited bandwidth of the wireless ad hoc networks, packet overhead, and hidden and the exposed terminal problems. The use of NACK control packets instead of ACKs can minimize network congestion and packet collisions. In this paper, we implement and investigate the use of NACKs over the RTS CTS handshake mechanism for single-hop wireless ad-hoc networks. The results show a significant performance improvement of throughput, and system delay for various network sizes and BERs. The wireless channel is time-varying where burst packet losses often occur during the fading or lossy handovers. In order to avoid unaccepted quality degradation of video streaming over 3G cellular networks, we propose and analyze a client-driven scalable cross-layer (CSC) retransmission scheme. Considering the perceptual importance of different video partitions under the real-time and bandwidth constraints, the proposed scheme uses the radio link-layer retransmission with priority to adapt conventional packet losses in wireless channels; furthermore, it uses the adaptive transport-layer retransmission to provide end-to-end quality-of-service (QoS) guarantees over cellular networks. The simulation experiments show that the proposed scheme can effectively improve the perceptual quality of 3G video streaming as compared to the traditional deadline-based scheme without the prioritized link-layer retransmission. We present a reliable broadcast protocol designed for use in ad hoc networks. The protocol ensures reliable, in-order, duplicate-free delivery of objects to a node's one-hop neighbor set. The flexibility and efficiency of the protocol hinges on the fact that the responsibility for reliable delivery rests solely at the receiver. Furthermore, when used on top of an 802.11-like MAC layer, we show that characteristics of an RTS CTS mechanism can be used to further improve protocol performance.