The Coherent File Distribution Protocol

CFDP is a protocol that takes advantage of the broadcast nature of CSMA networks to speed up simultaneous one-to-many file transfers (e.g., when booting diskless workstations). The CFDP server listens and services requests for entire files or portions thereof. CFDP clients first determine whether the file they are interested in is already being transferred, in which case they "eavesdrop" and load as much of it as they can, or they initiate a new transfer. The clients timeout when the server stops transmitting, and if they are still missing parts of the file they request them with a block-transfer request. CFDP is a back-end protocol a front end is needed to handle naming and security issues. A simple such front end is also presented here

Instal·lar Debian GNU/Linux a SGI Indy

L'objectiu del projecte és instal·lar Debian GNU/Linux a una estació de treball SGI Indy, un ordinador que no té lector de CD ni (el model objecte d'estudi) disposa de disquetera. La novetat d'aquest projecte és que no s'havia instal·lat Debian GNU/Linux en màquines diferents d'un PC. El mètode era utilitzar la connexió de xarxa i comptar amb un altre ordinador. S'havien d'estudiar les possibilitats: bé si es disposava d'un compte d'usuari o bé de majors necessitats. S'ha instal·lat Debian GNU/Linux disposant d'un compte root i utilitzant un servidor DHCP (Dynamic Host Configuration Protocol) i un servidor TFTP (Trivial File Transfer Protocol). Com a resultat es disposa d'un ordinador amb un Sistema Operatiu no propietari i molt més conegut que l'anterior, fet que en facilita les tasques de manteniment i el seu ús com a material educatiu

Juniper Networks

Some relay agents extract lease information from the DHCP messages exchanged between the client and DHCP server. This lease information is used by relay agents for various purposes like antispoofing and prevention of flooding. RFC 4388 defines a mechanism for relay agents to retrieve the lease information from the DHCP server when this information is lost. The existing lease query mechanism is data-driven, which means that a relay agent can initiate the lease query only when it starts receiving data to and from the clients. In certain scenarios, this model is not scalable. This document first looks at issues in the existing mechanism and then proposes a new query type, query by Remote ID, to address these issues. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by th

SD-MCAN: A Software-Defined Solution for IP Mobility in Campus Area Networks

Campus Area Networks (CANs) are a subset of enterprise networks, comprised of a network core connecting multiple Local Area Networks (LANs) across a college campus. Traditionally, hosts connect to the CAN via a single point of attachment; however, the past decade has seen the employment of mobile computing rise dramatically. Mobile devices must obtain new Internet Protocol (IP) addresses at each LAN as they migrate, wasting address space and disrupting host services. To prevent these issues, modern CANs should support IP mobility: allowing devices to keep a single IP address as they migrate between LANs with low-latency handoffs. Traditional approaches to mobility may be difficult to deploy and often lead to inefficient routing, but Software-Defined Networking (SDN) provides an intriguing alternative. This thesis identifies necessary requirements for a software-defined IP mobility system and then proposes one such system, the Software-Defined Mobile Campus Area Network (SD-MCAN) architecture. SD-MCAN employs an OpenFlow-based hybrid, label-switched routing scheme to efficiently route traffic flows between mobile hosts on the CAN. The proposed architecture is then implemented as an application on the existing POX controller and evaluated on virtual and hardware testbeds. Experimental results show that SD-MCAN can process handoffs with less than 90 ms latency, suggesting that the system can support data-intensive services on mobile host devices. Finally, the POX prototype is open-sourced to aid in future research

Enabling Graceful Software Upgrades in Distributed Systems

In today’s world, we are highly dependent on software systems together with devices for almost every task in our day to day life. Software system upgrades are released whenever it is necessary to accommodate the ever-changing user’s needs. The devices we use to run the software systems might be of different configurations, and we might be running different versions of these software systems on the devices. In such events, it is not possible for everybody to continue to run the same version of the software, nor can these billions of people using a software system update their software at the same time or even on the same day. Therefore, it has become necessary to design systems to maintain uninterrupted communication among the devices irrespective of software versions and device configurations. One of the key characteristics to achieve uninterrupted communication among the software systems is interoperability. In this thesis, we study techniques to achieve graceful software upgrades in distributed systems by implementing interoperability techniques. It is also observed that multiple software systems, like Bitcoin, failed to facilitate communication between versions. This thesis identifies the necessary elements to support graceful upgrade, i.e., the principles that are recommended for an upgrade to avoid interruption of user’s work or data. These elements were discovered by closely studying multiple widely popular distributed technologies that successfully achieved graceful upgrades. This thesis also analyzes the Bitcoin protocol and identifies the factors in its design that undermine the possibilities to have graceful upgrades in this cryptocurrency. A coding experiment was conducted to illustrate the efficacy of these principles and demonstrate graceful communications across three different versions of the same software

DHCP Monitoring Using IPFIX

Tato práce popisuje postupy pro sledování provozu síťových protokolů BOOTP, DHCP pro IPv4 a DHCP pro IPv6 pomocí netflow sondy FlowMon od společnosti Invea-tech. Je zde nastíněna problematika těchto protokolů, funkčnost sondy FlowMon, obecný popis NetFlow a vlastní popis řešení pro sběr a vyhodnocení dat. Byla provedena důkladná analýza a poté byly sepsány moduly pro sondu FlowMon pro možnost monitoringu zmíněných protokolů. Jejich implementace, způsob testování a vyhodnocení získaných dat je v této práci popsán.This thesis describes procedures for traffic monitoring of network protocols BOOTP, DHCP for IPv4 and DHCP for IPv6 through netflow probes FlowMoon made by Invea-tech. There are outlined the issues of these protocols, the functionality of the FlowMoon probe, a general description of NetFlow and the description of the solution for collecting and evaluation of the data. A deep analysis was made, and later on the modules for FlowMoon probe was written giving the possibility to monitoring of these protocols. Their implementation, method of testing and evaluation of gathered data is described in this paper.

Automatic bootstrapping of OpenFlow networks

OpenFlow decouples the control plane functionality from switches, and embeds it into one or more servers called controllers. One of the challenges of OpenFlow is to deploy a network where control and data traffic are transmitted on the same channel (in-band mode). Implementing such an in-band mode is complex, since switches have to search and establish a path to the controller (bootstrapping) through the other switches in the network. In this paper, we propose a method that facilitates this automatic bootstrapping of switches. In this method, the controller establishes its own control network through the neighbor switches that are connected to it by the OpenFlow protocol. We measure suitability of the proposed method by performing bootstrapping experiments in different types of topologies: linear, ring, star and mesh topologies. The experimental results show that the proposed method allows bootstrapping in a minimal time, which makes it suitable even for a large network