3 Search Results for "Parham, Mahmoud"

Document
Brief Announcement
DOI: 10.4230/LIPIcs.DISC.2022.52
Brief Announcement: Temporal Locality in Online Algorithms

Authors: Maciej Pacut, Mahmoud Parham, Joel Rybicki, Stefan Schmid, Jukka Suomela, and Aleksandr Tereshchenko

Published in: LIPIcs, Volume 246, 36th International Symposium on Distributed Computing (DISC 2022)

Abstract
Online algorithms make decisions based on past inputs, with the goal of being competitive against an algorithm that sees also future inputs. In this work, we introduce time-local online algorithms; these are online algorithms in which the output at any given time is a function of only T latest inputs. Our main observation is that time-local online algorithms are closely connected to local distributed graph algorithms: distributed algorithms make decisions based on the local information in the spatial dimension, while time-local online algorithms make decisions based on the local information in the temporal dimension. We formalize this connection, and show how we can directly use the tools developed to study distributed approximability of graph optimization problems to prove upper and lower bounds on the competitive ratio achieved with time-local online algorithms. Moreover, we show how to use computational techniques to synthesize optimal time-local algorithms.
Cite as

Maciej Pacut, Mahmoud Parham, Joel Rybicki, Stefan Schmid, Jukka Suomela, and Aleksandr Tereshchenko. Brief Announcement: Temporal Locality in Online Algorithms. In 36th International Symposium on Distributed Computing (DISC 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 246, pp. 52:1-52:3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)

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@InProceedings{pacut_et_al:LIPIcs.DISC.2022.52,
  author =	{Pacut, Maciej and Parham, Mahmoud and Rybicki, Joel and Schmid, Stefan and Suomela, Jukka and Tereshchenko, Aleksandr},
  title =	{{Brief Announcement: Temporal Locality in Online Algorithms}},
  booktitle =	{36th International Symposium on Distributed Computing (DISC 2022)},
  pages =	{52:1--52:3},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-255-6},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{246},
  editor =	{Scheideler, Christian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2022.52},
  URN =		{urn:nbn:de:0030-drops-172431},
  doi =		{10.4230/LIPIcs.DISC.2022.52},
  annote =	{Keywords: Online algorithms, distributed algorithms}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2020.26
Maximally Resilient Replacement Paths for a Family of Product Graphs

Authors: Mahmoud Parham, Klaus-Tycho Foerster, Petar Kosic, and Stefan Schmid

Published in: LIPIcs, Volume 184, 24th International Conference on Principles of Distributed Systems (OPODIS 2020)

Abstract
Modern communication networks support fast path restoration mechanisms which allow to reroute traffic in case of (possibly multiple) link failures, in a completely decentralized manner and without requiring global route reconvergence. However, devising resilient path restoration algorithms is challenging as these algorithms need to be inherently local. Furthermore, the resulting failover paths often have to fulfill additional requirements related to the policy and function implemented by the network, such as the traversal of certain waypoints (e.g., a firewall). This paper presents local algorithms which ensure a maximally resilient path restoration for a large family of product graphs, including the widely used tori and generalized hypercube topologies. Our algorithms provably ensure that even under multiple link failures, traffic is rerouted to the other endpoint of every failed link whenever possible (i.e. detouring failed links), enforcing waypoints and hence accounting for the network policy. The algorithms are particularly well-suited for emerging segment routing networks based on label stacks.
Cite as

Mahmoud Parham, Klaus-Tycho Foerster, Petar Kosic, and Stefan Schmid. Maximally Resilient Replacement Paths for a Family of Product Graphs. In 24th International Conference on Principles of Distributed Systems (OPODIS 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 184, pp. 26:1-26:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@InProceedings{parham_et_al:LIPIcs.OPODIS.2020.26,
  author =	{Parham, Mahmoud and Foerster, Klaus-Tycho and Kosic, Petar and Schmid, Stefan},
  title =	{{Maximally Resilient Replacement Paths for a Family of Product Graphs}},
  booktitle =	{24th International Conference on Principles of Distributed Systems (OPODIS 2020)},
  pages =	{26:1--26:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-176-4},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{184},
  editor =	{Bramas, Quentin and Oshman, Rotem and Romano, Paolo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2020.26},
  URN =		{urn:nbn:de:0030-drops-135111},
  doi =		{10.4230/LIPIcs.OPODIS.2020.26},
  annote =	{Keywords: Product Graphs, Resilience, Failures, Routing}
}
Document
DOI: 10.4230/LIPIcs.OPODIS.2018.13
Local Fast Segment Rerouting on Hypercubes

Authors: Klaus-Tycho Foerster, Mahmoud Parham, Stefan Schmid, and Tao Wen

Published in: LIPIcs, Volume 125, 22nd International Conference on Principles of Distributed Systems (OPODIS 2018)

Abstract
Fast rerouting is an essential mechanism in any dependable communication network, allowing to quickly, i.e., locally, recover from network failures, without invoking the control plane. However, while locality ensures a fast reaction, the absence of global information also renders the design of highly resilient fast rerouting algorithms more challenging. In this paper, we study algorithms for fast rerouting in emerging Segment Routing (SR) networks, where intermediate destinations can be added to packets by nodes along the path. Our main contribution is a maximally resilient polynomial-time fast rerouting algorithm for SR networks based on a hypercube topology. Our algorithm is attractive as it preserves the original paths (and hence waypoints traversed along the way), and does not require packets to carry failure information. We complement our results with an integer linear program formulation for general graphs and exploratory simulation results.
Cite as

Klaus-Tycho Foerster, Mahmoud Parham, Stefan Schmid, and Tao Wen. Local Fast Segment Rerouting on Hypercubes. In 22nd International Conference on Principles of Distributed Systems (OPODIS 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 125, pp. 13:1-13:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)

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@InProceedings{foerster_et_al:LIPIcs.OPODIS.2018.13,
  author =	{Foerster, Klaus-Tycho and Parham, Mahmoud and Schmid, Stefan and Wen, Tao},
  title =	{{Local Fast Segment Rerouting on Hypercubes}},
  booktitle =	{22nd International Conference on Principles of Distributed Systems (OPODIS 2018)},
  pages =	{13:1--13:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-098-9},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{125},
  editor =	{Cao, Jiannong and Ellen, Faith and Rodrigues, Luis and Ferreira, Bernardo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.OPODIS.2018.13},
  URN =		{urn:nbn:de:0030-drops-100739},
  doi =		{10.4230/LIPIcs.OPODIS.2018.13},
  annote =	{Keywords: segment routing, local fast failover, link failures}
}
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