Matteo Croce 58deb77cc5 bonding: balance ICMP echoes in layer3+4 mode
The bonding uses the L4 ports to balance flows between slaves. As the ICMP
protocol has no ports, those packets are sent all to the same device:

    # tcpdump -qltnni veth0 ip |sed 's/^/0: /' &
    # tcpdump -qltnni veth1 ip |sed 's/^/1: /' &
    # ping -qc1 192.168.0.2
    1: IP 192.168.0.1 > 192.168.0.2: ICMP echo request, id 315, seq 1, length 64
    1: IP 192.168.0.2 > 192.168.0.1: ICMP echo reply, id 315, seq 1, length 64
    # ping -qc1 192.168.0.2
    1: IP 192.168.0.1 > 192.168.0.2: ICMP echo request, id 316, seq 1, length 64
    1: IP 192.168.0.2 > 192.168.0.1: ICMP echo reply, id 316, seq 1, length 64
    # ping -qc1 192.168.0.2
    1: IP 192.168.0.1 > 192.168.0.2: ICMP echo request, id 317, seq 1, length 64
    1: IP 192.168.0.2 > 192.168.0.1: ICMP echo reply, id 317, seq 1, length 64

But some ICMP packets have an Identifier field which is
used to match packets within sessions, let's use this value in the hash
function to balance these packets between bond slaves:

    # ping -qc1 192.168.0.2
    0: IP 192.168.0.1 > 192.168.0.2: ICMP echo request, id 303, seq 1, length 64
    0: IP 192.168.0.2 > 192.168.0.1: ICMP echo reply, id 303, seq 1, length 64
    # ping -qc1 192.168.0.2
    1: IP 192.168.0.1 > 192.168.0.2: ICMP echo request, id 304, seq 1, length 64
    1: IP 192.168.0.2 > 192.168.0.1: ICMP echo reply, id 304, seq 1, length 64

Aso, let's use a flow_dissector_key which defines FLOW_DISSECTOR_KEY_ICMP,
so we can balance pings encapsulated in a tunnel when using mode encap3+4:

    # ping -q 192.168.1.2 -c1
    0: IP 192.168.0.1 > 192.168.0.2: GREv0, length 102: IP 192.168.1.1 > 192.168.1.2: ICMP echo request, id 585, seq 1, length 64
    0: IP 192.168.0.2 > 192.168.0.1: GREv0, length 102: IP 192.168.1.2 > 192.168.1.1: ICMP echo reply, id 585, seq 1, length 64
    # ping -q 192.168.1.2 -c1
    1: IP 192.168.0.1 > 192.168.0.2: GREv0, length 102: IP 192.168.1.1 > 192.168.1.2: ICMP echo request, id 586, seq 1, length 64
    1: IP 192.168.0.2 > 192.168.0.1: GREv0, length 102: IP 192.168.1.2 > 192.168.1.1: ICMP echo reply, id 586, seq 1, length 64

Signed-off-by: Matteo Croce <mcroce@redhat.com>
Reviewed-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-10-30 17:21:35 -07:00
2019-10-13 16:37:36 -07:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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