Feature #5138

Configure default MTU for UDP faces

Added by Junxiao Shi 2 months ago. Updated about 18 hours ago.

Target version:
Start date:
Due date:
% Done:


Estimated time:
3.00 h


Currently, nfdc face create command allows setting MTU when creating or updating a UDP face.
This allows the operator to select NDNLPv2 fragmentation instead of IP fragmentation, which is effective in working around networks that blocks/drops IPv4 fragments or IPv6 fragments.
However, MTU option is unavailable for on-demand faces: all on-demand UDP transports are created with the default MTU of MAX_NDN_PACKET_SIZE i.e. 8800 octets.

In global NDN testbed operations, it has been discovered that some NAT middleboxes and firewalls could block egress IPv4 fragments, causing UDP connections between unrestricted end hosts and testbed routers to become unreliable or fail, when a large packet is transmitted from the testbed router to the end host.
It is necessary for the testbed router in such environments to lower the MTU of on-demand UDP faces, so that outgoing packets would use NDNLP fragmentation.

This issue is to introduce a configuration option:

    unicast_mtu 1452

This face_system.udp.unicast_mtu option accepts a positive number that sets the MTU for on-demand UDP faces.
It also serves as the default MTU for UDP faces created through the nfdc face create command when the mtu option is unspecified.
It shall be an error to set a value that is smaller than MIN_MTU or greater than MAX_NDN_PACKET_SIZE.

Related issues

Related to NFD - Feature #4005: NDNLPv2 fragmentation instead of IP fragmentation on UDP tunnelsClosedEric Newberry


Updated by Junxiao Shi 2 months ago

  • Related to Feature #4005: NDNLPv2 fragmentation instead of IP fragmentation on UDP tunnels added

Updated by Junxiao Shi 6 days ago

  • Status changed from New to In Progress
  • Assignee set to Junxiao Shi
  • % Done changed from 0 to 60
That's a lucky Change number - same as the default UDP port number.


Updated by Junxiao Shi 3 days ago

  • Status changed from In Progress to Code review
  • % Done changed from 60 to 100

Updated by Davide Pesavento 3 days ago

  • Description updated (diff)

Updated by Junxiao Shi about 18 hours ago

  • Description updated (diff)
  • Status changed from Code review to Closed

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