github.com/cilium/cilium@v1.16.2/Documentation/network/concepts/fragmentation.rst (about)

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     2  
     3      WARNING: You are looking at unreleased Cilium documentation.
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     6  
     7  .. _concepts_fragmentation:
     8  
     9  IPv4 Fragment Handling
    10  ======================
    11  
    12  By default, Cilium configures the eBPF datapath to perform IP fragment tracking
    13  to allow protocols that do not support segmentation (such as UDP) to
    14  transparently transmit large messages over the network. This feature may be
    15  configured using the following options:
    16  
    17  - ``--enable-ipv4-fragment-tracking``: Enable or disable IPv4 fragment
    18    tracking. Enabled by default.
    19  - ``--bpf-fragments-map-max``: Control the maximum number of active concurrent
    20    connections using IP fragmentation. For the defaults, see `bpf_map_limitations`.
    21  
    22  .. note::
    23  
    24      When running Cilium with kube-proxy, fragmented NodePort traffic may break due
    25      to a kernel bug where route MTU is not respected for forwarded packets. Cilium
    26      fragments tracking requires the first logical fragment to arrive first. Due to the
    27      kernel bug, additional fragmentation on the outer encapsulation layer may happen
    28      that causes packet reordering and results in a failure in tracking the fragments.
    29  
    30      The kernel bug has been `fixed <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=02a1b175b0e92d9e0fa5df3957ade8d733ceb6a0>`_
    31      and backported to all maintained kernel versions. If you observe connectivity problems,
    32      ensure that the kernel package on your nodes has been upgraded recently before
    33      reporting an issue.
    34  
    35  .. include:: ../../beta.rst