+ <code>false</code> to disable.</dd>
+ </dl>
+ </dd>
+ <dt><code>ipsec_gre</code></dt>
+ <dd>An Ethernet over RFC 2890 Generic Routing Encapsulation over
+ IPv4 IPsec tunnel. Each tunnel (including those of type
+ <code>gre</code>) must be uniquely identified by the
+ combination of <code>remote_ip</code> and
+ <code>local_ip</code>. Note that if two ports are defined
+ that are the same except one has an optional identifier and
+ the other does not, the more specific one is matched first.
+ The following options may be specified in the
+ <ref column="options"/> column:
+ <dl>
+ <dt><code>remote_ip</code></dt>
+ <dd>Required. The tunnel endpoint.</dd>
+ </dl>
+ <dl>
+ <dt><code>local_ip</code></dt>
+ <dd>Optional. The destination IP that received packets must
+ match. Default is to match all addresses.</dd>
+ </dl>
+ <dl>
+ <dt><code>ipsec_psk</code></dt>
+ <dd>Required. Specifies a pre-shared key for authentication
+ that must be identical on both sides of the tunnel.</dd>
+ </dl>
+ <dl>
+ <dt><code>in_key</code></dt>
+ <dd>Optional. The GRE key that received packets must contain.
+ It may either be a 32-bit number (no key and a key of 0 are
+ treated as equivalent) or the word <code>flow</code>. If
+ <code>flow</code> is specified then any key will be accepted
+ and the key will be placed in the <code>tun_id</code> field
+ for matching in the flow table. The ovs-ofctl manual page
+ contains additional information about matching fields in
+ OpenFlow flows. Default is no key.</dd>
+ </dl>
+ <dl>
+ <dt><code>out_key</code></dt>
+ <dd>Optional. The GRE key to be set on outgoing packets. It may
+ either be a 32-bit number or the word <code>flow</code>. If
+ <code>flow</code> is specified then the key may be set using
+ the <code>set_tunnel</code> Nicira OpenFlow vendor extension (0
+ is used in the absence of an action). The ovs-ofctl manual
+ page contains additional information about the Nicira OpenFlow
+ vendor extensions. Default is no key.</dd>
+ </dl>
+ <dl>
+ <dt><code>key</code></dt>
+ <dd>Optional. Shorthand to set <code>in_key</code> and
+ <code>out_key</code> at the same time.</dd>
+ </dl>
+ <dl>
+ <dt><code>tos</code></dt>
+ <dd>Optional. The value of the ToS bits to be set on the
+ encapsulating packet. It may also be the word
+ <code>inherit</code>, in which case the ToS will be copied from
+ the inner packet if it is IPv4 or IPv6 (otherwise it will be
+ 0). Note that the ECN fields are always inherited. Default is
+ 0.</dd>
+ </dl>
+ <dl>
+ <dt><code>ttl</code></dt>
+ <dd>Optional. The TTL to be set on the encapsulating packet.
+ It may also be the word <code>inherit</code>, in which case the
+ TTL will be copied from the inner packet if it is IPv4 or IPv6
+ (otherwise it will be the system default, typically 64).
+ Default is the system default TTL.</dd>
+ </dl>
+ <dl>
+ <dt><code>csum</code></dt>
+ <dd>Optional. Compute GRE checksums on outgoing packets.
+ Checksums present on incoming packets will be validated
+ regardless of this setting. Note that GRE checksums
+ impose a significant performance penalty as they cover the
+ entire packet. As the contents of the packet is typically
+ covered by L3 and L4 checksums, this additional checksum only
+ adds value for the GRE and encapsulated Ethernet headers.
+ Default is disabled, set to <code>true</code> to enable.</dd>
+ </dl>
+ <dl>
+ <dt><code>pmtud</code></dt>
+ <dd>Optional. Enable tunnel path MTU discovery. If enabled
+ ``ICMP destination unreachable - fragmentation'' needed
+ messages will be generated for IPv4 packets with the DF bit set
+ and IPv6 packets above the minimum MTU if the packet size
+ exceeds the path MTU minus the size of the tunnel headers. It
+ also forces the encapsulating packet DF bit to be set (it is
+ always set if the inner packet implies path MTU discovery).
+ Note that this option causes behavior that is typically
+ reserved for routers and therefore is not entirely in
+ compliance with the IEEE 802.1D specification for bridges.
+ Default is enabled, set to <code>false</code> to disable.</dd>