| encapsulation-limit | uint32 | 0 | How many additional levels of encapsulation are permitted to be prepended to packets. This property applies only to IPv6 tunnels. To disable this option, add 0x1 (ip6-ign-encap-limit) to ip-tunnel flags. | 
| flags | uint32 | 0 | Tunnel flags. Currently, the following values are supported: 0x1 (ip6-ign-encap-limit), 0x2 (ip6-use-orig-tclass), 0x4 (ip6-use-orig-flowlabel), 0x8 (ip6-mip6-dev), 0x10 (ip6-rcv-dscp-copy), 0x20 (ip6-use-orig-fwmark). They are valid only for IPv6 tunnels. | 
| flow-label | uint32 | 0 | The flow label to assign to tunnel packets. This property applies only to IPv6 tunnels. | 
| fwmark | uint32 | 0 | The fwmark value to assign to tunnel packets. This property can be set to a non zero value only on VTI and VTI6 tunnels. | 
| input-key | string |  | The key used for tunnel input packets; the property is valid only for certain tunnel modes (GRE, IP6GRE). If empty, no key is used. | 
| local | string |  | The local endpoint of the tunnel; the value can be empty, otherwise it must contain an IPv4 or IPv6 address. | 
| mode | uint32 | 0 | The tunneling mode. Valid values: 1 (ipip), 2 (gre), 3 (sit), 4 (isatap), 5 (vti), 6 (ip6ip6), 7 (ipip6), 8 (ip6gre), 9 (vti6), 10 (gretap) and 11 (ip6gretap) | 
| mtu | uint32 | 0 | If non-zero, only transmit packets of the specified size or smaller, breaking larger packets up into multiple fragments. | 
| output-key | string |  | The key used for tunnel output packets; the property is valid only for certain tunnel modes (GRE, IP6GRE). If empty, no key is used. | 
| parent | string |  | If given, specifies the parent interface name or parent connection UUID the new device will be bound to so that tunneled packets will only be routed via that interface. | 
| path-mtu-discovery | boolean | TRUE | Whether to enable Path MTU Discovery on this tunnel. | 
| remote | string |  | The remote endpoint of the tunnel; the value must contain an IPv4 or IPv6 address. | 
| tos | uint32 | 0 | The type of service (IPv4) or traffic class (IPv6) field to be set on tunneled packets. | 
| ttl | uint32 | 0 | The TTL to assign to tunneled packets. 0 is a special value meaning that packets inherit the TTL value. |