[ovs-dev] [PATCHv5] tunnel: Add layer 2 IPv6 GRE encapsulation support.

Gregory Rose gvrose8192 at gmail.com
Tue Jul 2 17:42:34 UTC 2019


On 7/1/2019 12:45 PM, William Tu wrote:
> The patch adds ip6gre support. Tunnel type 'ip6gre' with packet_type=
> legacy_l2 is a layer 2 GRE tunnel over IPv6, carrying inner ethernet packets
> and encap with GRE header with outer IPv6 header.  Encapsulation of layer 3
> packet over IPv6 GRE, ip6gre, is not supported yet.  I tested it by running:
>    # make check-kernel TESTSUITEFLAGS='-k ip6gre'
> under kernel 5.2 and for userspace:
>    # make check TESTSUITEFLAGS='-k ip6gre'

On a Ubuntu 18.04 system with the distro provided 4.15.0-43-generic 
kernel I get the following splat:

[  510.428122] general protection fault: 0000 [#1] SMP PTI
[  510.428192] Modules linked in: openvswitch(OE) tunnel6 
nf_conntrack_ipv6 nf_nat_ipv6 nf_defrag_ipv6 netconsole xt_CHECKSUM 
iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat 
nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack 
xt_tcpudp bridge stp llc iptable_filter snd_hda_codec_generic 
snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_pcm snd_timer 
joydev snd soundcore input_leds mac_hid serio_raw qemu_fw_cfg 
sch_fq_codel ib_iser rdma_cm iw_cm ib_cm ib_core iscsi_tcp libiscsi_tcp 
libiscsi scsi_transport_iscsi ip_tables x_tables autofs4 btrfs 
zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq 
async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 multipath linear 
hid_generic usbhid hid crct10dif_pclmul crc32_pclmul ghash_clmulni_intel 
pcbc qxl ttm
[  510.428536]  drm_kms_helper syscopyarea sysfillrect sysimgblt 
fb_sys_fops aesni_intel aes_x86_64 crypto_simd glue_helper cryptd drm 
psmouse i2c_piix4 virtio_net virtio_blk pata_acpi floppy
[  510.428609] CPU: 0 PID: 35 Comm: kworker/0:1 Tainted: G OE    
4.15.0-43-generic #46-Ubuntu
[  510.428646] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
[  510.428727] Workqueue: ipv6_addrconf addrconf_dad_work
[  510.428763] RIP: 0010:__gre6_xmit+0x11f/0x2c0 [openvswitch]
[  510.428787] RSP: 0018:ffffb1e840d8f3e8 EFLAGS: 00010286
[  510.428820] RAX: 00000000ffffffea RBX: ffff9dfaa8a10000 RCX: 
0000000000000000
[  510.428848] RDX: ffff0000af55e000 RSI: 0000000000000040 RDI: 
ffff9dfaae9cda00
[  510.428875] RBP: ffffb1e840d8f440 R08: 0000000000005865 R09: 
ffffb1e840d8f464
[  510.428903] R10: 0000000000002000 R11: ffff9dfab7002c00 R12: 
ffff9dfaae9cda00
[  510.428930] R13: 0000000000000000 R14: ffffb1e840d8f468 R15: 
00000000ffffffff
[  510.428972] FS:  0000000000000000(0000) GS:ffff9dfabfc00000(0000) 
knlGS:0000000000000000
[  510.429003] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  510.429950] CR2: 000055d347881e60 CR3: 00000001b760a005 CR4: 
00000000003606f0
[  510.430860] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 
0000000000000000
[  510.431683] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 
0000000000000400
[  510.432494] Call Trace:
[  510.433318]  ip6gre_tunnel_xmit+0x103/0x530 [openvswitch]
[  510.434083]  ? __wake_up_common+0x73/0x130
[  510.434891]  ? __wake_up_common_lock+0x8e/0xc0
[  510.435763]  __ip6gre_tunnel_xmit+0x12/0x20 [openvswitch]
[  510.436562]  ovs_vport_send+0xd4/0x170 [openvswitch]
[  510.437393]  do_output+0x53/0x160 [openvswitch]
[  510.438221]  do_execute_actions+0x9a1/0x1880 [openvswitch]
[  510.438968]  ? __wake_up_common+0x73/0x130
[  510.439746]  ? __wake_up_common_lock+0x8e/0xc0
[  510.440515]  ? __skb_flow_dissect+0xd29/0x1450
[  510.441295]  ovs_execute_actions+0x4c/0x120 [openvswitch]
[  510.442030]  ? ovs_execute_actions+0x4c/0x120 [openvswitch]
[  510.442819]  ovs_dp_process_packet+0x95/0x150 [openvswitch]
[  510.443649]  ? ovs_ct_update_key+0x85/0xe0 [openvswitch]
[  510.444492]  ovs_vport_receive+0x7e/0xd0 [openvswitch]
[  510.445294]  ? select_idle_sibling+0x29/0x410
[  510.446200]  ? select_task_rq_fair+0x637/0xab0
[  510.446990]  ? __update_load_avg_se.isra.38+0x1c0/0x1d0
[  510.447763]  ? try_to_wake_up+0x59/0x480
[  510.448549]  internal_dev_xmit+0x28/0x60 [openvswitch]
[  510.449356]  dev_hard_start_xmit+0xa8/0x210
[  510.450173]  __dev_queue_xmit+0x690/0x7d0
[  510.450908]  ? mroute6_socket+0x78/0xa0
[  510.451704]  dev_queue_xmit+0x10/0x20
[  510.452413]  ? dev_queue_xmit+0x10/0x20
[  510.453101]  ip6_finish_output2+0x339/0x520
[  510.453776]  ? ipv6_get_l4proto+0x96/0xe0 [nf_conntrack_ipv6]
[  510.454429]  ip6_finish_output+0x13a/0x1b0
[  510.455049]  ? ip6_finish_output+0x13a/0x1b0
[  510.455662]  ip6_output+0x6c/0x110
[  510.456285]  ? ip6_fragment+0x9f0/0x9f0
[  510.456825]  NF_HOOK.constprop.34+0x45/0xb0
[  510.457401]  ? ipv6_icmp_sysctl_init+0x40/0x40
[  510.458022]  mld_sendpack+0x163/0x210
[  510.458572]  mld_send_initial_cr.part.23+0x86/0xa0
[  510.459214]  ipv6_mc_dad_complete+0x2b/0x40
[  510.459744]  addrconf_dad_completed+0x302/0x370
[  510.460268]  ? __switch_to_asm+0x40/0x70
[  510.460768]  ? __switch_to_asm+0x34/0x70
[  510.461272]  ? __switch_to_asm+0x40/0x70
[  510.461766]  ? __switch_to_asm+0x34/0x70
[  510.462271]  ? __switch_to_asm+0x40/0x70
[  510.462738]  addrconf_dad_work+0x2b8/0x440
[  510.463226]  ? addrconf_dad_work+0x2b8/0x440
[  510.463694]  ? finish_task_switch+0x72/0x220
[  510.464192]  process_one_work+0x1de/0x410
[  510.464655]  ? process_one_work+0x1de/0x410
[  510.465112]  worker_thread+0x32/0x410
[  510.465576]  kthread+0x121/0x140
[  510.466035]  ? process_one_work+0x410/0x410
[  510.466527]  ? kthread_create_worker_on_cpu+0x70/0x70
[  510.467002]  ret_from_fork+0x35/0x40
[  510.467527] Code: 00 01 b8 65 58 00 00 44 0f 44 c0 80 bb ef 08 00 00 
00 0f 84 70 01 00 00 49 8b 54 24 38 4c 89 4d b0 b8 ea ff ff ff 48 85 d2 
74 0f <0f> b6 8a f1 00 00 00 83 e1 03 80 f9 03 74 5a 48 8b 7d c8 65 48
[  510.468522] RIP: __gre6_xmit+0x11f/0x2c0 [openvswitch] RSP: 
ffffb1e840d8f3e8
[  510.469051] ---[ end trace ec787407c9ed3a64 ]---
[  510.469589] Kernel panic - not syncing: Fatal exception in interrupt
[  510.470789] Kernel Offset: 0x1e000000 from 0xffffffff81000000 
(relocation range: 0xffffffff80000000-0xffffffffbfffffff)
[  510.471360] ---[ end Kernel panic - not syncing: Fatal exception in 
interrupt

I'm investigating the cause.

- Greg


> Signed-off-by: William Tu <u9012063 at gmail.com>
> ---
> v1-v2
>   - rebase to master
> v2-v3
>    - update documentation suggested by Eli
> v3-v4
>    - squash Eli's documentation
> v4-v5
>    - remove using 'ip6gretap', use only 'ip6gre' with
>      options:packet_type=legacy_l2
> ---
>   Documentation/faq/configuration.rst | 13 +++++++
>   NEWS                                |  1 +
>   datapath/linux/compat/ip6_gre.c     |  2 +-
>   lib/dpif-netlink-rtnl.c             |  8 ++++-
>   tests/system-traffic.at             | 40 +++++++++++++++++++++
>   tests/tunnel-push-pop-ipv6.at       | 69 +++++++++++++++++++++++++++++++++++++
>   vswitchd/vswitch.xml                | 32 ++++++++++-------
>   7 files changed, 151 insertions(+), 14 deletions(-)
>
> diff --git a/Documentation/faq/configuration.rst b/Documentation/faq/configuration.rst
> index cb2c6b4eca98..ff3b71a5d4ef 100644
> --- a/Documentation/faq/configuration.rst
> +++ b/Documentation/faq/configuration.rst
> @@ -212,6 +212,19 @@ Q: Does Open vSwitch support ERSPAN?
>                   options:erspan_ver=2 options:erspan_dir=1 \
>                   options:erspan_hwid=4
>   
> +Q: Does Open vSwitch support IPv6 GRE?
> +
> +    A: Yes. L2 tunnel interface GRE over IPv6 is supported.
> +    L3 GRE tunnel over IPv6 is not supported.
> +
> +    ::
> +
> +        $ ovs-vsctl add-br br0
> +        $ ovs-vsctl add-port br0 at_gre0 -- \
> +                set int at_gre0 type=ip6gre \
> +                options:remote_ip=fc00:100::1 \
> +                options:packet_type=legacy_l2
> +
>   Q: How do I connect two bridges?
>   
>       A: First, why do you want to do this?  Two connected bridges are not much
> diff --git a/NEWS b/NEWS
> index a38ab258fc6c..c7e84ed7931d 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -47,6 +47,7 @@ Post-v2.11.0
>      - Linux datapath:
>        * Support for the kernel versions 4.19.x and 4.20.x.
>        * Support for the kernel version 5.0.x.
> +   - Add L2 GRE tunnel over IPv6 support.
>   
>   
>   v2.11.0 - 19 Feb 2019
> diff --git a/datapath/linux/compat/ip6_gre.c b/datapath/linux/compat/ip6_gre.c
> index ca4e66133570..ab50c72d0753 100644
> --- a/datapath/linux/compat/ip6_gre.c
> +++ b/datapath/linux/compat/ip6_gre.c
> @@ -2550,7 +2550,7 @@ static struct rtnl_link_ops ip6gre_link_ops __read_mostly = {
>   };
>   
>   static struct rtnl_link_ops ip6gre_tap_ops __read_mostly = {
> -	.kind		= "ip6gre",
> +	.kind		= "ip6gretap",
>   	.maxtype	= RPL_IFLA_GRE_MAX,
>   	.policy		= ip6gre_policy,
>   	.priv_size	= sizeof(struct ip6_tnl),
> diff --git a/lib/dpif-netlink-rtnl.c b/lib/dpif-netlink-rtnl.c
> index 2e23a8c14fcf..582274c46774 100644
> --- a/lib/dpif-netlink-rtnl.c
> +++ b/lib/dpif-netlink-rtnl.c
> @@ -104,7 +104,13 @@ vport_type_to_kind(enum ovs_vport_type type,
>       case OVS_VPORT_TYPE_IP6ERSPAN:
>           return "ip6erspan";
>       case OVS_VPORT_TYPE_IP6GRE:
> -        return "ip6gre";
> +        if (tnl_cfg->pt_mode == NETDEV_PT_LEGACY_L2) {
> +            return "ip6gretap";
> +        } else if (tnl_cfg->pt_mode == NETDEV_PT_LEGACY_L3) {
> +            return NULL;
> +        } else {
> +            return NULL;
> +        }
>       case OVS_VPORT_TYPE_NETDEV:
>       case OVS_VPORT_TYPE_INTERNAL:
>       case OVS_VPORT_TYPE_LISP:
> diff --git a/tests/system-traffic.at b/tests/system-traffic.at
> index d23ee897b0b2..8ea450887076 100644
> --- a/tests/system-traffic.at
> +++ b/tests/system-traffic.at
> @@ -340,6 +340,46 @@ NS_CHECK_EXEC([at_ns0], [ping -s 3200 -q -c 3 -i 0.3 -w 2 10.1.1.100 | FORMAT_PI
>   OVS_TRAFFIC_VSWITCHD_STOP
>   AT_CLEANUP
>   
> +AT_SETUP([datapath - ping over ip6gre L2 tunnel])
> +OVS_CHECK_KERNEL_EXCL(3, 10, 4, 15)
> +OVS_CHECK_GRE()
> +OVS_CHECK_ERSPAN()
> +
> +OVS_TRAFFIC_VSWITCHD_START()
> +ADD_BR([br-underlay])
> +
> +AT_CHECK([ovs-ofctl add-flow br0 "actions=normal"])
> +AT_CHECK([ovs-ofctl add-flow br-underlay "actions=normal"])
> +
> +ADD_NAMESPACES(at_ns0)
> +
> +dnl Set up underlay link from host into the namespace using veth pair.
> +ADD_VETH(p0, at_ns0, br-underlay, "fc00:100::1/96", [], [], nodad)
> +AT_CHECK([ip addr add dev br-underlay "fc00:100::100/96" nodad])
> +AT_CHECK([ip link set dev br-underlay up])
> +
> +dnl Set up tunnel endpoints on OVS outside the namespace and with a native
> +dnl linux device inside the namespace.
> +ADD_OVS_TUNNEL6([ip6gre], [br0], [at_gre0], [fc00:100::1], [10.1.1.100/24],
> +                [options:packet_type=legacy_l2])
> +ADD_NATIVE_TUNNEL6([ip6gretap], [ns_gretap0], [at_ns0], [fc00:100::100],
> +                   [10.1.1.1/24], [local fc00:100::1])
> +
> +OVS_WAIT_UNTIL([ip netns exec at_ns0 ping6 -c 2 fc00:100::100])
> +
> +dnl First, check the underlay
> +NS_CHECK_EXEC([at_ns0], [ping6 -q -c 3 -i 0.3 -w 2 fc00:100::100 | FORMAT_PING], [0], [dnl
> +3 packets transmitted, 3 received, 0% packet loss, time 0ms
> +])
> +
> +dnl Okay, now check the overlay with different packet sizes
> +NS_CHECK_EXEC([at_ns0], [ping -q -c 3 -i 0.3 -w 2 10.1.1.100 | FORMAT_PING], [0], [dnl
> +3 packets transmitted, 3 received, 0% packet loss, time 0ms
> +])
> +OVS_TRAFFIC_VSWITCHD_STOP
> +AT_CLEANUP
> +
> +
>   AT_SETUP([datapath - ping over erspan v1 tunnel])
>   OVS_CHECK_KERNEL_EXCL(3, 10, 4, 15)
>   OVS_CHECK_GRE()
> diff --git a/tests/tunnel-push-pop-ipv6.at b/tests/tunnel-push-pop-ipv6.at
> index cbdd5a32f719..59723e63b845 100644
> --- a/tests/tunnel-push-pop-ipv6.at
> +++ b/tests/tunnel-push-pop-ipv6.at
> @@ -1,5 +1,74 @@
>   AT_BANNER([tunnel_push_pop_ipv6])
>   
> +AT_SETUP([tunnel_push_pop_ipv6 - ip6gre])
> +
> +OVS_VSWITCHD_START([add-port br0 p0 -- set Interface p0 type=dummy ofport_request=1 other-config:hwaddr=aa:55:aa:55:00:00])
> +AT_CHECK([ovs-vsctl add-br int-br -- set bridge int-br datapath_type=dummy], [0])
> +AT_CHECK([ovs-vsctl add-port int-br t2 -- set Interface t2 type=ip6gre \
> +                       options:remote_ip=2001:cafe::92 ofport_request=2\
> +                       options:packet_type=legacy_l2
> +                       ], [0])
> +
> +AT_CHECK([ovs-appctl dpif/show], [0], [dnl
> +dummy at ovs-dummy: hit:0 missed:0
> +  br0:
> +    br0 65534/100: (dummy-internal)
> +    p0 1/1: (dummy)
> +  int-br:
> +    int-br 65534/2: (dummy-internal)
> +    t2 2/6: (ip6gre: remote_ip=2001:cafe::92)
> +])
> +
> +dnl First setup dummy interface IP address, then add the route
> +dnl so that tnl-port table can get valid IP address for the device.
> +AT_CHECK([ovs-appctl netdev-dummy/ip6addr br0 2001:cafe::88/24], [0], [OK
> +])
> +AT_CHECK([ovs-appctl netdev-dummy/ip4addr br0 1.1.2.88/24], [0], [OK
> +])
> +AT_CHECK([ovs-appctl ovs/route/add 2001:cafe::92/24 br0], [0], [OK
> +])
> +
> +AT_CHECK([ovs-ofctl add-flow br0 action=normal])
> +
> +dnl Check Neighbour discovery.
> +AT_CHECK([ovs-vsctl -- set Interface p0 options:pcap=p0.pcap])
> +
> +AT_CHECK([ovs-appctl netdev-dummy/receive int-br 'in_port(2),eth(src=aa:55:aa:55:00:00,dst=f8:bc:12:ff:ff:ff),eth_type(0x0800),ipv4(src=1.1.3.92,dst=1.1.3.88,proto=1,tos=0,ttl=64,frag=no),icmp(type=0,code=0)'])
> +AT_CHECK([ovs-pcap p0.pcap > p0.pcap.txt 2>&1])
> +
> +AT_CHECK([cat p0.pcap.txt | grep 92aa55aa55000086dd6000000000203aff2001cafe | uniq], [0], [dnl
> +3333ff000092aa55aa55000086dd6000000000203aff2001cafe000000000000000000000088ff0200000000000000000001ff00009287004d48000000002001cafe0000000000000000000000920101aa55aa550000
> +])
> +
> +dnl
> +AT_CHECK([ovs-appctl netdev-dummy/receive p0 'in_port(1),eth(src=f8:bc:12:44:34:b6,dst=aa:55:aa:55:00:00),eth_type(0x86dd),ipv6(src=2001:cafe::92,dst=2001:cafe::88,label=0,proto=58,tclass=0,hlimit=255,frag=no),icmpv6(type=136,code=0),nd(target=2001:cafe::92,sll=00:00:00:00:00:00,tll=f8:bc:12:44:34:b6)'])
> +
> +AT_CHECK([ovs-appctl tnl/arp/show | tail -n+3 | sort], [0], [dnl
> +2001:cafe::92                                 f8:bc:12:44:34:b6   br0
> +])
> +
> +AT_CHECK([ovs-appctl tnl/ports/show |sort], [0], [dnl
> +Listening ports:
> +ip6gre_sys (6) ref_cnt=1
> +])
> +
> +dnl Check IPv6 GRE tunnel pop
> +AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(1),eth(src=f8:bc:12:44:34:b6,dst=aa:55:aa:55:00:00),eth_type(0x86dd),ipv6(src=2001:cafe::92,dst=2001:cafe::88,label=0,proto=47,tclass=0x0,hlimit=64)'], [0], [stdout])
> +AT_CHECK([tail -1 stdout], [0],
> +  [Datapath actions: tnl_pop(6)
> +])
> +
> +dnl Check IPv6 GRE tunnel push
> +AT_CHECK([ovs-ofctl add-flow int-br action=2])
> +AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(2),eth(src=f8:bc:12:44:34:b6,dst=aa:55:aa:55:00:01),eth_type(0x0800),ipv4(src=1.1.3.88,dst=1.1.3.112,proto=47,tos=0,ttl=64,frag=no)'], [0], [stdout])
> +
> +AT_CHECK([tail -1 stdout], [0],
> +  [Datapath actions: clone(tnl_push(tnl_port(6),header(size=58,type=109,eth(dst=f8:bc:12:44:34:b6,src=aa:55:aa:55:00:00,dl_type=0x86dd),ipv6(src=2001:cafe::88,dst=2001:cafe::92,label=0,proto=47,tclass=0x0,hlimit=64),gre((flags=0x0,proto=0x6558))),out_port(100)),1)
> +])
> +
> +OVS_VSWITCHD_STOP
> +AT_CLEANUP
> +
>   AT_SETUP([tunnel_push_pop_ipv6 - ip6erspan])
>   
>   OVS_VSWITCHD_START([add-port br0 p0 -- set Interface p0 type=dummy ofport_request=1 other-config:hwaddr=aa:55:aa:55:00:00])
> diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
> index bf4b6f8dc621..d143bcc06a2b 100644
> --- a/vswitchd/vswitch.xml
> +++ b/vswitchd/vswitch.xml
> @@ -2561,10 +2561,16 @@
>   
>             <dt><code>gre</code></dt>
>             <dd>
> -            Generic Routing Encapsulation (GRE) over IPv4/IPv6 tunnel,
> +            Generic Routing Encapsulation (GRE) over IPv4 tunnel,
>               configurable to encapsulate layer 2 or layer 3 traffic.
>             </dd>
>   
> +          <dt><code>ip6gre</code></dt>
> +          <dd>
> +            Generic Routing Encapsulation (GRE) over IPv6 tunnel,
> +            encapsulate layer 2 traffic.
> +          </dd>
> +
>             <dt><code>vxlan</code></dt>
>             <dd>
>               <p>
> @@ -2623,8 +2629,8 @@
>       <group title="Tunnel Options">
>         <p>
>           These options apply to interfaces with <ref column="type"/> of
> -        <code>geneve</code>, <code>gre</code>, <code>vxlan</code>,
> -        <code>lisp</code> and <code>stt</code>.
> +        <code>geneve</code>, <code>gre</code>, <code>ip6gre</code>,
> +        <code>vxlan</code>, <code>lisp</code> and <code>stt</code>.
>         </p>
>   
>         <p>
> @@ -2921,10 +2927,10 @@
>           </column>
>         </group>
>   
> -      <group title="Tunnel Options: gre, geneve, and vxlan">
> +      <group title="Tunnel Options: gre, ip6gre, geneve, and vxlan">
>           <p>
> -          <code>gre</code>, <code>geneve</code>, and
> -          <code>vxlan</code> interfaces support these options.
> +          <code>gre</code>, <code>ip6gre</code>, <code>geneve</code>,
> +          and <code>vxlan</code> interfaces support these options.
>           </p>
>   
>           <column name="options" key="csum" type='{"type": "boolean"}'>
> @@ -2938,8 +2944,9 @@
>             <p>
>               When using the upstream Linux kernel module, computation of
>               checksums for <code>geneve</code> and <code>vxlan</code> requires
> -            Linux kernel version 4.0 or higher. <code>gre</code> supports
> -            checksums for all versions of Open vSwitch that support GRE.
> +            Linux kernel version 4.0 or higher. <code>gre</code> and
> +            <code>ip6gre</code> support checksums for all versions of
> +            Open vSwitch that support GRE.
>               The out of tree kernel module distributed as part of OVS
>               can compute all tunnel checksums on any kernel version that it
>               is compatible with.
> @@ -2951,10 +2958,11 @@
>         <group title="Tunnel Options: IPsec">
>           <p>
>             Setting any of these options enables IPsec support for a given
> -          tunnel.  <code>gre</code>, <code>geneve</code>, <code>vxlan</code>,
> -          and <code>stt</code> interfaces support these options.  See the
> -          <code>IPsec</code> section in the <ref table="Open_vSwitch"/> table
> -          for a description of each mode.
> +          tunnel.  <code>gre</code>, <code>ip6gre</code>,
> +          <code>geneve</code>, <code>vxlan</code> and <code>stt</code>
> +          interfaces support these options.  See the <code>IPsec</code>
> +          section in the <ref table="Open_vSwitch"/> table for a description
> +          of each mode.
>           </p>
>           <column name="options" key="psk" type='{"type": "string"}'>
>             <p>



More information about the dev mailing list