ryu中的match項

上圖是一張流表項的組成部分，其中match fileds是用來做流表比對的，當一條資料流過來，該如何對這條流進行處理，交換機會先對資料進行比對，如果比對結果和一條流表項的match fileds是符合的，那麼便會對這條流做相應的處理，在ryu中match fileds中包含哪些可以來比對流的項呢？我們來看源碼。在ryu中比對域是由OFPMatch這個類來生成的一個實體，根據這個類的說明我們可以了解它定義了哪些比對項以及在下流表時match fileds是如何生成的。

class OFPMatch(StringifyMixin):
    """
    Flow Match Structure

    This class is implementation of the flow match structure having
    compose/query API.
    There are new API and old API for compatibility. the old API is
    supposed to be removed later.

    You can define the flow match by the keyword arguments.
    The following arguments are available.

    ================ =============== ==================================
    Argument         Value           Description
    ================ =============== ==================================
    in_port          Integer 32bit   Switch input port
    in_phy_port      Integer 32bit   Switch physical input port
    metadata         Integer 64bit   Metadata passed between tables
    eth_dst          MAC address     Ethernet destination address
    eth_src          MAC address     Ethernet source address
    eth_type         Integer 16bit   Ethernet frame type
    vlan_vid         Integer 16bit   VLAN id
    vlan_pcp         Integer 8bit    VLAN priority
    ip_dscp          Integer 8bit    IP DSCP (6 bits in ToS field)
    ip_ecn           Integer 8bit    IP ECN (2 bits in ToS field)
    ip_proto         Integer 8bit    IP protocol
    ipv4_src         IPv4 address    IPv4 source address
    ipv4_dst         IPv4 address    IPv4 destination address
    tcp_src          Integer 16bit   TCP source port
    tcp_dst          Integer 16bit   TCP destination port
    udp_src          Integer 16bit   UDP source port
    udp_dst          Integer 16bit   UDP destination port
    sctp_src         Integer 16bit   SCTP source port
    sctp_dst         Integer 16bit   SCTP destination port
    icmpv4_type      Integer 8bit    ICMP type
    icmpv4_code      Integer 8bit    ICMP code
    arp_op           Integer 16bit   ARP opcode
    arp_spa          IPv4 address    ARP source IPv4 address
    arp_tpa          IPv4 address    ARP target IPv4 address
    arp_sha          MAC address     ARP source hardware address
    arp_tha          MAC address     ARP target hardware address
    ipv6_src         IPv6 address    IPv6 source address
    ipv6_dst         IPv6 address    IPv6 destination address
    ipv6_flabel      Integer 32bit   IPv6 Flow Label
    icmpv6_type      Integer 8bit    ICMPv6 type
    icmpv6_code      Integer 8bit    ICMPv6 code
    ipv6_nd_target   IPv6 address    Target address for ND
    ipv6_nd_sll      MAC address     Source link-layer for ND
    ipv6_nd_tll      MAC address     Target link-layer for ND
    mpls_label       Integer 32bit   MPLS label
    mpls_tc          Integer 8bit    MPLS TC
    mpls_bos         Integer 8bit    MPLS BoS bit
    pbb_isid         Integer 24bit   PBB I-SID
    tunnel_id        Integer 64bit   Logical Port Metadata
    ipv6_exthdr      Integer 16bit   IPv6 Extension Header pseudo-field
    ================ =============== ==================================

    Example::

        >>> # compose
        >>> match = parser.OFPMatch(
        ...     in_port=1,
        ...     eth_type=0x86dd,
        ...     ipv6_src=('2001:db8:bd05:1d2:288a:1fc0:1:10ee',
        ...               'ffff:ffff:ffff:ffff::'),
        ...     ipv6_dst='2001:db8:bd05:1d2:288a:1fc0:1:10ee')
        >>> # query
        >>> if 'ipv6_src' in match:
        ...     print match['ipv6_src']
        ...
        ('2001:db8:bd05:1d2:288a:1fc0:1:10ee', 'ffff:ffff:ffff:ffff::')

    .. Note::

        For VLAN id match field, special values are defined in OpenFlow Spec.

        1) Packets with and without a VLAN tag

            - Example::

                match = parser.OFPMatch()

            - Packet Matching

                ====================== =====
                non-VLAN-tagged        MATCH
                VLAN-tagged(vlan_id=3) MATCH
                VLAN-tagged(vlan_id=5) MATCH
                ====================== =====

        2) Only packets without a VLAN tag

            - Example::

                match = parser.OFPMatch(vlan_vid=0x0000)

            - Packet Matching

                ====================== =====
                non-VLAN-tagged        MATCH
                VLAN-tagged(vlan_id=3)   x
                VLAN-tagged(vlan_id=5)   x
                ====================== =====

        3) Only packets with a VLAN tag regardless of its value

            - Example::

                match = parser.OFPMatch(vlan_vid=(0x1000, 0x1000))

            - Packet Matching

                ====================== =====
                non-VLAN-tagged          x
                VLAN-tagged(vlan_id=3) MATCH
                VLAN-tagged(vlan_id=5) MATCH
                ====================== =====

        4) Only packets with VLAN tag and VID equal

            - Example::

                match = parser.OFPMatch(vlan_vid=(0x1000 | 3))

            - Packet Matching

                ====================== =====
                non-VLAN-tagged          x
                VLAN-tagged(vlan_id=3) MATCH
                VLAN-tagged(vlan_id=5)   x
                ====================== =====
    """