This paper describes a technique for tracing anonymous packet flooding attacks in the Internet back towards their source. This work is motivated by the increased frequency and sophistication of denial-of-service attacks and by the difficulty in tracing packets with incorrect, or “spoofed”, source addresses. In this paper we describe a general purpose traceback mechanism based on probabilistic packet marking in the network. Our approach allows a victim to identify the network path(s) traversed by attack traffic without requiring interactive operational support from Internet Service Providers (ISPs). Moreover, this traceback can be performed “post-mortem ” – after an attack has completed. We present an implementation of this technology that is incrementally deployable, (mostly) backwards compatible and can be efficiently implemented using conventional technology. 1.

Current TCP protocols have lower throughput performance in satellite networks mainly due to the effects of long propagation delays and high link error rates. In this paper, a new congestion control scheme called TCP-Peach is introduced for satellite networks. TCP-Peach is composed of two new algorithms, namely Sudden Start and Rapid Recovery, as well as the two traditional TCP algorithms, Congestion Avoidance and Fast Retransmit. The new algorithms are based on the novel concept of using dummy segments to probe the availability of network resources without carrying any new information to the sender. Dummy segments are treated as low-priority segments and accordingly they do not effect the delivery of actual data traffic. Simulation experiments show that TCP-Peach outperforms other TCP schemes for satellite networks in terms of goodput. It also provides a fair share of network resources.

The capacity allocation problem in a network that is to be shared by noncooperative users is considered. Each user decides independently upon its routing strategy, so as to optimize its individual performance objective. The operating points of the network are the Nash equilibria of the underlying routing game. The network designer aims to allocate link capacities, so that the resulting Nash equilibria are efficient, according to some systemwide performance criterion. In general, the solution of such design problems is complex and at times counterintuitive, since adding link capacity might lead to degradation of user performance. For systems of parallel links, we show that such paradoxes do not occur and that the capacity allocation problem has a simple and intuitive optimal solution, that coincides with the solution in the single-user case.

Abstract-Aggressive research on gigabit-per-second networks has led to dramatic improvements in network transmission speeds. One result of these improvements has been to put pressure on router technology to keep pace. This paper describes a router, nearly completed, which is more than fast enough to keep up with the latest transmission technologies. The router has a backplane speed of 50 Gh/s and can forward tens of millions of packets per second. Index Terms-Data communications, internetworking, packet switching, routing.

AbstractÐAn anycast packet is one that should be delivered to one member in a group of designated recipients. Using anycast services may considerably simplify some applications. Little work has been done on routing anycast packets. In this paper, we propose and analyze a routing protocol for anycast message. It is composed of two subprotocols: the routing table establishment subprotocol and the packet forwarding subprotocol. In the routing table establishment subprotocol, we propose four methods (SSP, MIN-D, SBT, and CBT) for enforcing an order among routers for the purpose of loop prevention. These methods differ from each other on information used to maintain orders, the impact on QoS, and the compatibility to the existing routing protocols. In the packet forwarding subprotocol, we propose a Weighted-Random Selection (WRS) approach for multiple path selection in order to balance network traffic. In particular, the fixed and adaptive methods are proposed to determine the weights. Both of them explicitly take into account the characteristics of distribution of anycast recipient group while the adaptive method uses the dynamic information of the anycast traffic as well. Correctness property of the protocol is formally proven. Extensive simulation is performed to evaluate our newly designed protocol. Performance data shows that the loop-prevention methods and the WRS approaches have great impact on the performance in terms of average end-to-end packet delay. In particular, the protocol using the SBT or CBT loop-prevention methods and the adaptive WRS approach performs very close to a dynamic optimal routing protocol in most cases. Index TermsÐAnycast message, multiple path routing, shortest path first, weight assignment. 1

The IP address lookup problem is one of the major bottlenecks in high performance routers. Previous solutions to this problem first describe it in the general terms of longest prefix matching and, then, are experimented on real routing tables $T$. In this paper, we follow the opposite direction. We start out from the experimental analysis of real data and, based upon our findings, we provide a new and simple solution to the IP address lookup problem. More precisely, our solution for $m$-bit IP addresses is a reasonable trade-off between performing a binary search on $T$ with $O(\log |T|)$ accesses, where $|T|$ is the number of entries in $T$, and executing a single access on a table of $2^m$ entries obtained by fully expanding $T$. While the previous results start out from space-efficient data structures and aim at lowering the $O(\log |T|)$ access cost, we start out from the expanded table with $2^m$ entries and aim at compressing it without an excessive increase in the number of accesses. Our algorithm takes \emph{exactly three} memory accesses and occupies $O(2^{m/2} |T|^2)$ space in the worst case. Experiments on real routing tables for $m=32$ show that the space bound is overly pessimistic. Our solution occupies approximately one megabyte for the MaeEast routing table (which has $|T|\approx 44,000$ and requires approximately 250 KB) and, thus, takes three \emph{cache} accesses on any processor with 1 MB of L2 cache. According to the measurement obtained by the VTune tool on a Pentium II processor, each lookup requires 3 additional clock cycles besides the ones needed for the memory accesses. Assuming a clock cycle of 3.33 nanoseconds and an L2 cache latency of 15 nanoseconds, search of MaeEast can be estimated in 55 nanoseconds or, equivalently, our method performs 18 millions of lookups per second.

Packet probing is an important Internet measurement technique, supporting the investigation of packet delay, path, and loss. Current packet probing techniques use Internet Protocols such as the Internet Control Message Protocol (ICMP), the User Datagram Protocol (UDP), and the Transmission Control Protocol (TCP). These protocols were not originally designed for measurement purposes. Current packet probing techniques have several limitations that can be avoided. The IP Measurement Protocol (IPMP) is presented as a protocol that addresses several of the limitations discussed.

This paper presents a master/slave cellular-based mobile ad hoc network architecture for multihop multimedia communications. The proposed network is based on a new paradigm for solving the problem of cluster-based ad hoc routing when utilizing existing wireless local area network (WLAN) technologies. The network architecture is a mixture of two different types of networks: infrastructure (master-and-slave) and ad hoc. In this architecture, the participating slave nodes (SNs) in each cluster communicate with each other via their respective master nodes (MNs) in an infrastructure network. In contrast to traditional cellular networks where the base stations are fixed (e.g., interconnected via a wired backbone), in this network the MNs (e.g., base stations) are mobile; thus, interconnection is accomplished dynamically and in an ad hoc manner. For network implementation, the IEEE 802.11 WLAN has been deployed. Since there is no stationary node in this network, all the nodes in a cluster may have to move together as a group. However, in order to allow a mobile node to move to another cluster, which requires changing its point of attachment, a handoff process utilizing Mobile IP version 6 (IPv6) has been considered. For ad hoc routing between the master nodes (i.e., MNs), the Ad hoc On-demand Distance Vector (AODV) Routing protocol has been deployed. In assessing the network performance, field test trials have been carried out to measure the proposed network performance. These measurements include packet loss, delays under various test conditions such as a change of ad hoc route, handoffs, etc. Keywords—Ad hoc networks, cluster networks, IEEE 802.11, mobile IP, wireless local area network (WLAN). I.

In this paper we study the computational complexity and effectiveness of a concept we term "N-hub ShortestPath Routing" in IP networks. N-hub Shortest-Path Routing allows the ingress node of a routing domain to determine up to N intermediate nodes ("hubs") through which a packet will traverse before reaching its final destination. This facilitates better utilization of the network resources, while allowing the network routers to continue to employ the simple and wellknown shortest-path routing paradigm. This concept has been suggested in the past but this paper is the first to offer an in-depth investigation of it. We apply this concept to the routing problem of minimizing the maximum load in the network. We show that the resulting routing problem is a difficult (NP-Complete) problem and that it is also hard to approximate. However, we propose efficient algorithms for solving this problem both in the online and the offline contexts. Our results show that Nhub Shortest-Path Routing can increase the network utilization significantly even for N =1. Hence, this routing paradigm should be considered as a powerful mechanism for the future datagram routing in the Internet.

An IP router must forward packets at gigabit speed in order to guarantee a good QoS.