Grade to the edge: How many unreliable nodes does it take to break a content delivery network?

Research output: Contribution to book/conference proceedings/anthology/reportConference contributionContributed


Delivering content from a network via a client-server architecture is expensive not only for content owners but also for network operators. Moving content closer to the end user is already used in Content Delivery Networks (CDN). Multi-Access Edge Computing (MEC) enables us to shift the content even closer by using the storage of end users. But, due to the large media files, storage and transport costs for peers increase significantly. Network Coding can reduce these costs. However, peers in CDNs tend to be highly fluctuating and often need to be restored, making continuous availability of data at the network edge a problem. While for uncoded data, individual packets lost due to peer failures can be tracked to determine availability, the availability of coded data is currently distinguished only in two cases: either there are still enough linearly independent packets to decode the file, or there are not. However, we have found that the network's combined coded cache loses quality over time due to recovery. This quality loss, which we refer to as grade, can be measured by very cost-effective monitoring. If the grade falls below a certain limit, we can intervene in the network by performing a cache refresh to prevent data becoming unavailable preemptively. In this paper, we present the cases in which such monitoring is useful, how the grade is calculated, and when a cache refresh is necessary. The results show that we can reduce network traffic by up to 34% with minimal storage costs through efficient monitoring.


Original languageEnglish
Title of host publication2022 IEEE 23rd International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM)
EditorsLiming Luke Chen, Tommaso Melodia, Eirini Eleni Tsiropoulou, Carla Fabiana Chiasserini, Raffaele Bruno, Shameek Bhattacharjee, Pantelis Frangoudis, Venkata Sriram Siddhardh Nadendla
Number of pages6
ISBN (electronic)978-1-6654-0876-9
Publication statusPublished - 16 Jun 2022

External IDs

Scopus 85137121193
Mendeley 2ae69eca-fa74-3f88-bb83-4c544360799a
dblp conf/wowmom/ZimmermannSCNF22
unpaywall 10.1109/wowmom54355.2022.00068
ORCID /0000-0001-7008-1537/work/142248618



  • CDN, Distributed Storage, IPFS, Monitoring, Network Coding, RLNC, Reliability