如何使用ipv6流量标签

Question

我在浏览IPv6时，看到了流标签，我的问题是，如何使用IPv6的流标签呢？有没有办法为IPv6头中的Flow Label字段配置一个默认值，有没有一个可配置的策略来处理收到的数据包中的Flow Label字段？

Answer 1

检查sysctl的。https:/www.kernel.orgdocDocumentationnetworkingip-sysctl.txt

flowlabel_consistency - BOOLEAN
    Protect the consistency (and unicity) of flow label.
    You have to disable it to use IPV6_FL_F_REFLECT flag on the
    flow label manager.
    TRUE: enabled
    FALSE: disabled
    Default: TRUE

auto_flowlabels - INTEGER
    Automatically generate flow labels based on a flow hash of the
    packet. This allows intermediate devices, such as routers, to
    identify packet flows for mechanisms like Equal Cost Multipath
    Routing (see RFC 6438).
    0: automatic flow labels are completely disabled
    1: automatic flow labels are enabled by default, they can be
       disabled on a per socket basis using the IPV6_AUTOFLOWLABEL
       socket option
    2: automatic flow labels are allowed, they may be enabled on a
       per socket basis using the IPV6_AUTOFLOWLABEL socket option
    3: automatic flow labels are enabled and enforced, they cannot
       be disabled by the socket option
    Default: 1

flowlabel_state_ranges - BOOLEAN
    Split the flow label number space into two ranges. 0-0x7FFFF is
    reserved for the IPv6 flow manager facility, 0x80000-0xFFFFF
    is reserved for stateless flow labels as described in RFC6437.
    TRUE: enabled
    FALSE: disabled
    Default: true

flowlabel_reflect - INTEGER
    Control flow label reflection. Needed for Path MTU
    Discovery to work with Equal Cost Multipath Routing in anycast
    environments. See RFC 7690 and:
    https://tools.ietf.org/html/draft-wang-6man-flow-label-reflection-01

    This is a bitmask.
    1: enabled for established flows

    Note that this prevents automatic flowlabel changes, as done
    in "tcp: change IPv6 flow-label upon receiving spurious retransmission"
    and "tcp: Change txhash on every SYN and RTO retransmit"

    2: enabled for TCP RESET packets (no active listener)
    If set, a RST packet sent in response to a SYN packet on a closed
    port will reflect the incoming flow label.

    4: enabled for ICMPv6 echo reply messages.

    Default: 0