MPTCP Sysfs variables¶
/proc/sys/net/mptcp/* Variables¶
- add_addr_timeout - INTEGER (seconds)
Set the maximum value of timeout after which an ADD_ADDR control message will be resent to an MPTCP peer that has not acknowledged a previous ADD_ADDR message. A dynamically estimated retransmission timeout based on the estimated connection round-trip-time is used if this value is lower than the maximum one.
Do not retransmit if set to 0.
The default value matches TCP_RTO_MAX. This is a per-namespace sysctl.
Default: 120
- add_addr_v6_port_drop_ts - BOOLEAN
Control whether preparing an ADD_ADDR with an IPv6 address and a port should drop the TCP timestamps option to have enough option space to send the signal.
If there is not enough option space, and the TCP timestamps option cannot be dropped, the signal cannot be sent. Note that dropping the TCP timestamps option for one packet of the connection could disrupt some middleboxes: even if it should be unlikely, they could drop the packet or block the connection. This is a per-namespace sysctl.
Default: 1 (enabled)
- allow_join_initial_addr_port - BOOLEAN
Allow peers to send join requests to the IP address and port number used by the initial subflow if the value is 1. This controls a flag that is sent to the peer at connection time, and whether such join requests are accepted or denied.
Joins to addresses advertised with ADD_ADDR are not affected by this value.
This is a per-namespace sysctl.
Default: 1
- available_path_managers - STRING
Shows the available path managers choices that are registered. More path managers may be available, but not loaded.
- available_schedulers - STRING
Shows the available schedulers choices that are registered. More packet schedulers may be available, but not loaded.
- blackhole_timeout - INTEGER (seconds)
Initial time period in second to disable MPTCP on active MPTCP sockets when a MPTCP firewall blackhole issue happens. This time period will grow exponentially when more blackhole issues get detected right after MPTCP is re-enabled and will reset to the initial value when the blackhole issue goes away.
0 to disable the blackhole detection. This is a per-namespace sysctl.
Default: 3600
- checksum_enabled - BOOLEAN
Control whether DSS checksum can be enabled.
DSS checksum can be enabled if the value is nonzero. This is a per-namespace sysctl.
Default: 0
- close_timeout - INTEGER (seconds)
Set the make-after-break timeout: in absence of any close or shutdown syscall, MPTCP sockets will maintain the status unchanged for such time, after the last subflow removal, before moving to TCP_CLOSE.
The default value matches TCP_TIMEWAIT_LEN. This is a per-namespace sysctl.
Default: 60
- enabled - BOOLEAN
Control whether MPTCP sockets can be created.
MPTCP sockets can be created if the value is 1. This is a per-namespace sysctl.
Default: 1 (enabled)
- path_manager - STRING
Set the default path manager name to use for each new MPTCP socket. In-kernel path management will control subflow connections and address advertisements according to per-namespace values configured over the MPTCP netlink API. Userspace path management puts per-MPTCP-connection subflow connection decisions and address advertisements under control of a privileged userspace program, at the cost of more netlink traffic to propagate all of the related events and commands.
This is a per-namespace sysctl.
“kernel” - In-kernel path manager
“userspace” - Userspace path manager
Default: “kernel”
- pm_type - INTEGER
Set the default path manager type to use for each new MPTCP socket. In-kernel path management will control subflow connections and address advertisements according to per-namespace values configured over the MPTCP netlink API. Userspace path management puts per-MPTCP-connection subflow connection decisions and address advertisements under control of a privileged userspace program, at the cost of more netlink traffic to propagate all of the related events and commands.
This is a per-namespace sysctl.
Deprecated since v6.15, use path_manager instead.
0 - In-kernel path manager
1 - Userspace path manager
Default: 0
- scheduler - STRING
Select the scheduler of your choice.
Support for selection of different schedulers. This is a per-namespace sysctl.
Default: “default”
- stale_loss_cnt - INTEGER
The number of MPTCP-level retransmission intervals with no traffic and pending outstanding data on a given subflow required to declare it stale. The packet scheduler ignores stale subflows. A low stale_loss_cnt value allows for fast active-backup switch-over, an high value maximize links utilization on edge scenarios e.g. lossy link with high BER or peer pausing the data processing.
This is a per-namespace sysctl.
Default: 4
- syn_retrans_before_tcp_fallback - INTEGER
The number of SYN + MP_CAPABLE retransmissions before falling back to TCP, i.e. dropping the MPTCP options. In other words, if all the packets are dropped on the way, there will be:
The initial SYN with MPTCP support
This number of SYN retransmitted with MPTCP support
The next SYN retransmissions will be without MPTCP support
0 means the first retransmission will be done without MPTCP options. >= 128 means that all SYN retransmissions will keep the MPTCP options. A lower number might increase false-positive MPTCP blackholes detections. This is a per-namespace sysctl.
Default: 2