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Yes, both endpoints will need to support it. Support for MPTCP is advertised through a TCP option during the setup phase of the connection. One of three things

Yes, both endpoints will need to support it. Support for MPTCP is advertised through a TCP option during the setup phase of the connection. One of three things can happen: - Both endpoints support MPTCP and announce it through the MPTCP option : MPTCP will be used. Subflows will be set-up if possible (i.e. if additional addresses are present on at least one of the endpoint) - One of the endpoints (say an ios7 device) supports it, but the other (say a webserver) doesn't : the server will ignore the MPTCP option (which it doesn't understand) and a normal, single path TCP connection will be used. - None of the endpoints support it, thus no MPTCP option will be sent, normal TCP will be used.

shawkinaw 13y ago
Perhaps this is why (according to the article) the usage in iOS is limited to Siri and navigation.
yalogin 13y ago
From what I read one of the main design decisions was to make sure the nodes along the route do not drop the packets which means it will be a TCP packet for all intents and purposes. So why should the other end change in this case?
- delinka 13y ago
  It's less about routing and more about connections. Typically, your client makes a single TCP connection for HTTP communication, all data requested on that connection is communicated on that connection. With a supporting server, multiple TCP connections can be used for the same HTTP connection. This doesn't help with transfer speed, but it improves TCP's ability to route around failure. One of your multiple TCP connections goes out, and another one (presumably on a different route) continues handling data transfer. With regular old TCP, the connection tends to fail and has to be re-established. Pointless Pontification: since TCP was designed to route around failure, multi-connection TCP sounds to me like an adaptation of technology to the "demands of business." What I mean is network operators seem to want to centralize their networks to reduce costs instead of distributing them to make them robust, thus the technologists are attempting to work around this "failure."
- songgao 13y ago
  It doesn't make sure the nodes along the route do not drop the packets. Nodes along the route would see those packets as normal TCP packets (which is by design because in this way routers in between don't have to change). But both end are aware of MPTCP and they may use multiple path. In this case, iOS is connecting to Siri server using both 4G and WiFi. They apparently go through different routers. This helps improve reliability when the device is at border of a WiFi coverage and is switching between 4G and WiFi back-and-forth. Using two path simultaneously would allow Siri to switch to the other route when one of them is showing significant packet loss.
MichaelApproved 13y ago
When MPTCP is established, which IP address would be reported to the server software?
- tedunangst 13y ago
  The first one.

shawkinaw 13y ago

Perhaps this is why (according to the article) the usage in iOS is limited to Siri and navigation.

yalogin 13y ago

From what I read one of the main design decisions was to make sure the nodes along the route do not drop the packets which means it will be a TCP packet for all intents and purposes. So why should the other end change in this case?

delinka 13y ago
It's less about routing and more about connections. Typically, your client makes a single TCP connection for HTTP communication, all data requested on that connection is communicated on that connection. With a supporting server, multiple TCP connections can be used for the same HTTP connection. This doesn't help with transfer speed, but it improves TCP's ability to route around failure. One of your multiple TCP connections goes out, and another one (presumably on a different route) continues handling data transfer. With regular old TCP, the connection tends to fail and has to be re-established. Pointless Pontification: since TCP was designed to route around failure, multi-connection TCP sounds to me like an adaptation of technology to the "demands of business." What I mean is network operators seem to want to centralize their networks to reduce costs instead of distributing them to make them robust, thus the technologists are attempting to work around this "failure."
songgao 13y ago
It doesn't make sure the nodes along the route do not drop the packets. Nodes along the route would see those packets as normal TCP packets (which is by design because in this way routers in between don't have to change). But both end are aware of MPTCP and they may use multiple path. In this case, iOS is connecting to Siri server using both 4G and WiFi. They apparently go through different routers. This helps improve reliability when the device is at border of a WiFi coverage and is switching between 4G and WiFi back-and-forth. Using two path simultaneously would allow Siri to switch to the other route when one of them is showing significant packet loss.

MichaelApproved 13y ago

When MPTCP is established, which IP address would be reported to the server software?

tedunangst 13y ago
The first one.