Packet Fragmentation in NDN: Why NDN Uses Hop-By-Hop Fragmentation (NDN Memo)

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A. Afanasyev, J. Shi, L. Wang, B. Zhang, and L. Zhang,
NDN Memo, Technical Report NDN-0032.
Revision 1, May 12 2015.

The Named Data Networking (NDN) architecture uses application-level data as units of communication, essentially giving applications much more fine grained control over network-level operations. However given the the wide spectrum of maximum transmission unit (MTU) sizes in today and future networks: which data unit size should NDN applications use? We believe that while applications should be aware of the prevalent MTU sizes in the network, application data units should not be constrained by the smallest possible MTU size among all networks. The question is then how to handle those NDN packets that exceed the link MTU size. In this paper we argue that in the context of NDN, hop-by-hop fragmentation and reassembly (HBH-FR) is the most consistent with the data-centric and session-less nature of NDN communication. We also show that, contrary to the common belief (due to misunderstanding of an earlier study), HBH-FR provides better performance tradeoffs compared to other fragmentation options.