Tunnel metadata manipulation actioTunnelumetadata manipulation action in tc(8)

       tunnel_key - Tunnel metadata manipulation

       tc ... action tunnel_key { unset | SET }

       SET  := set src_ip ADDRESS dst_ip ADDRESS id KEY_ID dst_port UDP_PORT [
               csum | nocsum ]

       The tunnel_key action combined with a shared IP tunnel  device,  allows
       to perform IP tunnel en- or decapsulation on a packet, reflected by the
       operation modes UNSET and SET.  The UNSET mode is optional - even with-
       out  using  it, the metadata information will be released automatically
       when packet processing will be finished.  UNSET function could be  used
       in cases when traffic is forwarded between two tunnels, where the meta-
       data from the first tunnel will be used for encapsulation done  by  the
       second tunnel.  SET mode requires the source and destination ip ADDRESS
       and the tunnel key id KEY_ID which will be used by the ip tunnel shared
       device  to  create  the  tunnel header. The tunnel_key action is useful
       only in combination with a mirred redirect action to a shared IP tunnel
       device  which  will  use the metadata (for SET ) and unset the metadata
       created by it (for UNSET ).

       unset  Unset the tunnel metadata created by the IP tunnel device.  This
              function  is  not  mandatory and might be used only in some spe-
              cific use cases (as explained above).

       set    Set tunnel metadata to be used by the IP tunnel device. Requires
              id , src_ip and dst_ip options.  dst_port is optional.

              id     Tunnel ID (for example VNI in VXLAN tunnel)

              src_ip Outer header source IP address (IPv4 or IPv6)

              dst_ip Outer header destination IP address (IPv4 or IPv6)

                     Outer header destination UDP port

                     Controlls  outer UDP checksum. When set to csum (which is
                     default),  the  outer  UDP  checksum  is  calculated  and
                     included  in  the  packets. When set to nocsum, outer UDP
                     checksum is zero. Note that when using zero UDP checksums
                     with  IPv6,  the other tunnel endpoint must be configured
                     to accept such packets.  In  Linux,  this  would  be  the
                     udp6zerocsumrx option for the VXLAN tunnel interface.

                     If  using nocsum with IPv6, be sure you know what you are
                     doing.  Zero  UDP  checksums  provide  weaker  protection
                     against corrupted packets. See RFC6935 for details.

       The following example encapsulates incoming ICMP packets on eth0 into a
       vxlan tunnel, by setting metadata to VNI 11, source  IP  and
       destination  IP, and by redirecting the packet with the meta-
       data to device vxlan0, which will do the actual encapsulation using the

              #tc qdisc add dev eth0 handle ffff: ingress
              #tc filter add dev eth0 protocol ip parent ffff: \
                flower \
                  ip_proto icmp \
                action tunnel_key set \
                  src_ip \
                  dst_ip \
                  id 11 \
                action mirred egress redirect dev vxlan0

       Here  is  an example of the unset function: Incoming VXLAN traffic with
       outer IP's and VNI 11 is decapsulated by vxlan0 and metadata  is  unset
       before redirecting to tunl1 device:

              #tc qdisc add dev eth0 handle ffff: ingress
              #tc filter add dev vxlan0 protocol ip parent ffff:   flower \
                     enc_src_ip enc_dst_ip enc_key_id 11   action tunnel_key unset  action mirred egress redirect dev tunl1


iproute2                          Tunnel metadata manipulation action in tc(8)
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