On the complexity of optimal request routing and content caching in heterogeneous cache networks

Mostafa Dehghan, Bo Jiang, Anand Seetharam, Ting He, Theodoros Salonidis, Jim Kurose, Don Towsley, Ramesh Sitaraman

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

In-network content caching has been deployed in both the Internet and cellular networks to reduce content-access delay. We investigate the problem of developing optimal joint routing and caching policies in a network supporting in-network caching with the goal of minimizing expected content-access delay. Here, needed content can either be accessed directly from a back-end server (where content resides permanently) or be obtained from one of multiple in-network caches. To access content, users must thus decide whether to route their requests to a cache or to the back-end server. In addition, caches must decide which content to cache. We investigate two variants of the problem, where the paths to the back-end server can be considered as either congestion-sensitive or congestion-insensitive, reflecting whether or not the delay experienced by a request sent to the back-end server depends on the request load, respectively. We show that the problem of optimal joint caching and routing is NP-complete in both cases. We prove that under the congestioninsensitive delay model, the problem can be solved optimally in polynomial time if each piece of content is requested by only one user, or when there are at most two caches in the network. We also identify the structural property of the user-cache graph that makes the problem NP-complete. For the congestion-sensitive delay model, we prove that the problem remains NP-complete even if there is only one cache in the network and each content is requested by only one user. We show that approximate solutions can be found for both cases within a (1 - 1/e) factor from the optimal, and demonstrate a greedy solution that is numerically shown to be within 1% of optimal for small problem sizes. Through trace-driven simulations, we evaluate the performance of our greedy solutions to joint caching and routing, which show up to 50% reduction in average delay over the solution of optimized routing to least recently used caches.

Original languageEnglish (US)
Article number7797148
Pages (from-to)1635-1648
Number of pages14
JournalIEEE/ACM Transactions on Networking
Volume25
Issue number3
DOIs
StatePublished - Jun 1 2017

Fingerprint

Servers
Computational complexity
Structural properties
Polynomials
Internet

All Science Journal Classification (ASJC) codes

  • Software
  • Computer Science Applications
  • Computer Networks and Communications
  • Electrical and Electronic Engineering

Cite this

Dehghan, M., Jiang, B., Seetharam, A., He, T., Salonidis, T., Kurose, J., ... Sitaraman, R. (2017). On the complexity of optimal request routing and content caching in heterogeneous cache networks. IEEE/ACM Transactions on Networking, 25(3), 1635-1648. [7797148]. https://doi.org/10.1109/TNET.2016.2636843
Dehghan, Mostafa ; Jiang, Bo ; Seetharam, Anand ; He, Ting ; Salonidis, Theodoros ; Kurose, Jim ; Towsley, Don ; Sitaraman, Ramesh. / On the complexity of optimal request routing and content caching in heterogeneous cache networks. In: IEEE/ACM Transactions on Networking. 2017 ; Vol. 25, No. 3. pp. 1635-1648.
@article{77feca8e663a4bbba8d674fb53cd0215,
title = "On the complexity of optimal request routing and content caching in heterogeneous cache networks",
abstract = "In-network content caching has been deployed in both the Internet and cellular networks to reduce content-access delay. We investigate the problem of developing optimal joint routing and caching policies in a network supporting in-network caching with the goal of minimizing expected content-access delay. Here, needed content can either be accessed directly from a back-end server (where content resides permanently) or be obtained from one of multiple in-network caches. To access content, users must thus decide whether to route their requests to a cache or to the back-end server. In addition, caches must decide which content to cache. We investigate two variants of the problem, where the paths to the back-end server can be considered as either congestion-sensitive or congestion-insensitive, reflecting whether or not the delay experienced by a request sent to the back-end server depends on the request load, respectively. We show that the problem of optimal joint caching and routing is NP-complete in both cases. We prove that under the congestioninsensitive delay model, the problem can be solved optimally in polynomial time if each piece of content is requested by only one user, or when there are at most two caches in the network. We also identify the structural property of the user-cache graph that makes the problem NP-complete. For the congestion-sensitive delay model, we prove that the problem remains NP-complete even if there is only one cache in the network and each content is requested by only one user. We show that approximate solutions can be found for both cases within a (1 - 1/e) factor from the optimal, and demonstrate a greedy solution that is numerically shown to be within 1{\%} of optimal for small problem sizes. Through trace-driven simulations, we evaluate the performance of our greedy solutions to joint caching and routing, which show up to 50{\%} reduction in average delay over the solution of optimized routing to least recently used caches.",
author = "Mostafa Dehghan and Bo Jiang and Anand Seetharam and Ting He and Theodoros Salonidis and Jim Kurose and Don Towsley and Ramesh Sitaraman",
year = "2017",
month = "6",
day = "1",
doi = "10.1109/TNET.2016.2636843",
language = "English (US)",
volume = "25",
pages = "1635--1648",
journal = "IEEE/ACM Transactions on Networking",
issn = "1063-6692",
publisher = "Institute of Electrical and Electronics Engineers Inc.",
number = "3",

}

Dehghan, M, Jiang, B, Seetharam, A, He, T, Salonidis, T, Kurose, J, Towsley, D & Sitaraman, R 2017, 'On the complexity of optimal request routing and content caching in heterogeneous cache networks', IEEE/ACM Transactions on Networking, vol. 25, no. 3, 7797148, pp. 1635-1648. https://doi.org/10.1109/TNET.2016.2636843

On the complexity of optimal request routing and content caching in heterogeneous cache networks. / Dehghan, Mostafa; Jiang, Bo; Seetharam, Anand; He, Ting; Salonidis, Theodoros; Kurose, Jim; Towsley, Don; Sitaraman, Ramesh.

In: IEEE/ACM Transactions on Networking, Vol. 25, No. 3, 7797148, 01.06.2017, p. 1635-1648.

Research output: Contribution to journalArticle

TY - JOUR

T1 - On the complexity of optimal request routing and content caching in heterogeneous cache networks

AU - Dehghan, Mostafa

AU - Jiang, Bo

AU - Seetharam, Anand

AU - He, Ting

AU - Salonidis, Theodoros

AU - Kurose, Jim

AU - Towsley, Don

AU - Sitaraman, Ramesh

PY - 2017/6/1

Y1 - 2017/6/1

N2 - In-network content caching has been deployed in both the Internet and cellular networks to reduce content-access delay. We investigate the problem of developing optimal joint routing and caching policies in a network supporting in-network caching with the goal of minimizing expected content-access delay. Here, needed content can either be accessed directly from a back-end server (where content resides permanently) or be obtained from one of multiple in-network caches. To access content, users must thus decide whether to route their requests to a cache or to the back-end server. In addition, caches must decide which content to cache. We investigate two variants of the problem, where the paths to the back-end server can be considered as either congestion-sensitive or congestion-insensitive, reflecting whether or not the delay experienced by a request sent to the back-end server depends on the request load, respectively. We show that the problem of optimal joint caching and routing is NP-complete in both cases. We prove that under the congestioninsensitive delay model, the problem can be solved optimally in polynomial time if each piece of content is requested by only one user, or when there are at most two caches in the network. We also identify the structural property of the user-cache graph that makes the problem NP-complete. For the congestion-sensitive delay model, we prove that the problem remains NP-complete even if there is only one cache in the network and each content is requested by only one user. We show that approximate solutions can be found for both cases within a (1 - 1/e) factor from the optimal, and demonstrate a greedy solution that is numerically shown to be within 1% of optimal for small problem sizes. Through trace-driven simulations, we evaluate the performance of our greedy solutions to joint caching and routing, which show up to 50% reduction in average delay over the solution of optimized routing to least recently used caches.

AB - In-network content caching has been deployed in both the Internet and cellular networks to reduce content-access delay. We investigate the problem of developing optimal joint routing and caching policies in a network supporting in-network caching with the goal of minimizing expected content-access delay. Here, needed content can either be accessed directly from a back-end server (where content resides permanently) or be obtained from one of multiple in-network caches. To access content, users must thus decide whether to route their requests to a cache or to the back-end server. In addition, caches must decide which content to cache. We investigate two variants of the problem, where the paths to the back-end server can be considered as either congestion-sensitive or congestion-insensitive, reflecting whether or not the delay experienced by a request sent to the back-end server depends on the request load, respectively. We show that the problem of optimal joint caching and routing is NP-complete in both cases. We prove that under the congestioninsensitive delay model, the problem can be solved optimally in polynomial time if each piece of content is requested by only one user, or when there are at most two caches in the network. We also identify the structural property of the user-cache graph that makes the problem NP-complete. For the congestion-sensitive delay model, we prove that the problem remains NP-complete even if there is only one cache in the network and each content is requested by only one user. We show that approximate solutions can be found for both cases within a (1 - 1/e) factor from the optimal, and demonstrate a greedy solution that is numerically shown to be within 1% of optimal for small problem sizes. Through trace-driven simulations, we evaluate the performance of our greedy solutions to joint caching and routing, which show up to 50% reduction in average delay over the solution of optimized routing to least recently used caches.

UR - http://www.scopus.com/inward/record.url?scp=85007039888&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85007039888&partnerID=8YFLogxK

U2 - 10.1109/TNET.2016.2636843

DO - 10.1109/TNET.2016.2636843

M3 - Article

AN - SCOPUS:85007039888

VL - 25

SP - 1635

EP - 1648

JO - IEEE/ACM Transactions on Networking

JF - IEEE/ACM Transactions on Networking

SN - 1063-6692

IS - 3

M1 - 7797148

ER -