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The Internet Networking Linux Technology

A 50 Gbps Connection With Multipath TCP 150

Posted by timothy
from the meanwhile-my-att-dsl-crawls-along-poorly dept.
First time accepted submitter Olivier Bonaventure writes "The TCP protocol is closely coupled with the underlying IP protocol. Once a TCP connection has been established through one IP address, the other packets of the connection must be sent from this address. This makes mobility and load balancing difficult. Multipath TCP is a new extension that solves these old problems by decoupling TCP from the underlying IP. A Multipath TCP connection can send packets over several interfaces/addresses simultaneously while remaining backward compatible with existing TCP applications. Multipath TCP has several use cases, including smartphones that can use both WiFi and 3G, or servers that can pool multiple high-speed interfaces. Christoph Paasch, Gregory Detal and their colleagues who develop the implementation of Multipath TCP in the Linux kernel have achieved 50 Gbps for a single TCP connection [note: link has source code and technical details] by pooling together six 10 Gbps interfaces."
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A 50 Gbps Connection With Multipath TCP

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  • Doesn't SCTP provide for these scenarios (and many more)?

    • by swillden (191260) <shawn-ds@willden.org> on Friday March 22, 2013 @09:15PM (#43253805) Homepage Journal

      Doesn't SCTP provide for these scenarios (and many more)?

      No.

      SCTP supports multiple paths between endpoints, but doesn't use them simultaneously. Rather, it picks a primary path to use for data transfers and has the ability to fail over to an alternate path in the event the primary fails.

      A quick glance at the MTCP RFC shows that it is essentially multiplexing packets over n separate TCP streams (called subflows). It's the responsibility of the TCP/IP stack (in the OS, generally) to make this multiplexing transparent to the application, so the application only sees one stream.

      • by butlerm (3112) on Saturday March 23, 2013 @02:44AM (#43255145)

        Work is underway for concurrent multipath transfer for SCTP as well. Also known as CMT-SCTP. There are significant challenges in doing this sort of thing though. SCTP wasn't designed for CMT, and probably needs much more radical changes than the current architects are proposing to do it well.

        Changes like subflows with independent sequence numbers and congestion windows, to start with. SCTP is much further ahead in the connection handling and security department, but MPTCP has the odd advantage of resorting to independent subflows to begin with, and if it can handle path failure properly, it might well be ahead in the CMT game, if byte stream semantics are all you need.

    • by c0lo (1497653) on Friday March 22, 2013 @09:39PM (#43253951)
      In my understanding (I might be wrong):

      1. SCTP - identified by a protocol number (132) - acts at the network layer. If a router along the route refuses SCTP, you are screwed; Advantage: is capable of UDP as well).

      2. MPTCP - relies on pure TCP for all the connection (acts at the transport layer and fixes the protocol to TCP) and set in place conventions between client-server to discuss over multiple paths. Advantage: no sane public network will try to block it (pretty much like using http on port 80). Disadvantage: TCP only.

      • by c0lo (1497653)
        Errata: not acts on but relies on/uses.
      • by butlerm (3112) on Saturday March 23, 2013 @01:52AM (#43255017)

        On the contrary, SCTP is a transport protocol just like TCP, except with a large number of added features. The main problem with SCTP has nothing to do with SCTP at all. It is that NAT devices do not support any transport protocol that they haven't been programmed for in advance. This makes SCTP next to impossible to deploy on a broad scale - NAT, that wart upon router-kind, is ubiquitous.

        TCP would have exactly the same problem if it were a new protocol. A NAT device requires relatively deep knowledge of TCP to support it at all. It play games with both ports and addresses, keeps track of connection state, and so on. Ordinary routers do no such thing. A NAT device is a transport layer proxy by another name.

        • by fa2k (881632) <pmbjornstad@gmai ... om minus painter> on Saturday March 23, 2013 @07:17AM (#43255885)

          Your comment is correct, but NAT is not the core problem. In a world without NAT people would still use stateful firewalls. Those firewalls should be configured to drop anything unknown, because as a principle whitelisting is better than blacklisting.

          • by butlerm (3112)

            A stateful firewall doesn't need to block transport layer protocols it doesn't understand in order to provide a meaningful level of security. All it needs to do is block packets from IP addresses that corresponding interior address has not recently communicated with, with a reasonable time out. UDP is handled much the same way today.

            If the developers of stateful IPv6 firewalls do not ship devices with such a reasonable configuration by default, they will block the deployment of new transport protocols ind

        • On the contrary, SCTP is a transport protocol just like TCP, except with a large number of added features. The main problem with SCTP has nothing to do with SCTP at all. It is that NAT devices do not support any transport protocol that they haven't been programmed for in advance. This makes SCTP next to impossible to deploy on a broad scale - NAT, that wart upon router-kind, is ubiquitous.

          On top of that, SCTP also won't take off in the IPv6 world (where NAT isn't an issue), purely because Microsoft are on record saying they're never going to support it.

          Which is a shame, because SCTP is actually a much better fit than TCP for almost all applications that currently use TCP, by virtue of the fact that it is packet based instead of stream based. Also, the multi-streaming would be very beneficial for HTTP, which is something that HTTP/2.0 is instead trying to bodge ontop of TCP.

      • 1. SCTP - identified by a protocol number (132) - acts at the network layer. If a router along the route refuses SCTP, you are screwed

        If your ISP is refusing to route protocols other than TCP/UDP/ICMP its time to change ISP - this will equally break GRE, AH, ESP, 6in4 and a whole host of other commonly used protocols.

        The other thing SCTP has going for it is that its packet based instead of stream based, which makes it more suitable for almost everything we currently use tcp for...

        • by gmack (197796)

          It isn't routers you need to worry about its home gateways and firewalls. From my experiments with it so far my ISP DSL modem doesnt allow it but my office firewall supports it fine (mainly because its Linux) but the CISCO ASA we have server side supports it poorly. With the ASA, it is all or nothing. I can allow all SCTP regardless of port or I can allow no SCTP.

    • by Olivier Bonaventure (2873367) on Saturday March 23, 2013 @04:43AM (#43255475)
      SCTP is cleaner than Multipath TCP, but it suffers from two drawbacks that hinder its deployment in today's Internet : - many middleboxes only support IP, ICMP and TCP and discard SCTP packets (or do not perform NAT correctly) - applications need to be modified to support SCTP Multipath TCP is an evolution to TCP that works with unmodified applications and unmodified middleboxes.
  • Request For Comments (Score:5, Informative)

    by Nethead (1563) <joe@nethead.com> on Friday March 22, 2013 @09:05PM (#43253753) Homepage Journal

    RFC 6182 [ietf.org] if anyone is interested.

    • by dreamchaser (49529) on Friday March 22, 2013 @09:16PM (#43253813) Homepage Journal

      The first part I read when I heard of this was the security concerns. While there's been a good attempt to address them [ietf.org] I am not 100% sold. I guess the proof will be in the pudding as the old saying goes. Anytime you make a new protocol, especially one that is more complex, you run the risk of increased vulnerability.

      • by swillden (191260) <shawn-ds@willden.org> on Friday March 22, 2013 @09:23PM (#43253867) Homepage Journal

        What sort of security concerns are you thinking of?

        An attacker who controls one of the paths can obviously modify, replace, delay or delete portions of the stream which are multiplexed onto that path. Such an attacker could probably perform a DoS that would shut down the entire stream (disclaimer: I haven't read the details). But of course ordinary TCP is subject to all the same attacks, if the attacker has control of the path that carries it. In many cases an attacker without control of the path can also execute DoS attacks against TCP (e.g. sending RSTs).

        I'm not saying there aren't any new vulnerabilities exposed, but I'm not seeing where they would lie. TCP is not secure in any useful sense, so it's hard to see how MTCP could be worse.

        • Oh I didn't say it would be worse, but the more complex any kind of system gets the more uncertainty is introduced. I certainly wasn't suggesting we not evolve protocols to tackle problems as technology advances. I'm just always cautious about security since IT security is my profession. The RFC I linked to is an interesting read about some of the security concerns we need to keep in mind as this gets implemented.

          • by Nethead (1563)

            I would think that since the data is on multiple and diverse wires it would make it harder to tap. Still security through obscurity but every bit helps.

          • by Anonymous Coward

            What I didn't see addressed in the RFC was the possibility that a connection established over a relatively secure channel (such as a VPN or leased line) might then find and use additional paths over less secure channels, such as the public Internet.

            • by Anonymous Coward

              What I didn't see addressed in the RFC was the possibility that a connection established over a relatively secure channel (such as a VPN or leased line) might then find and use additional paths over less secure channels, such as the public Internet.

              This is why I stay far away from the IETF and committies. People like yourself thinking they are most clever wasting everyones time on utter nonsense.

        • It's like frequency hopping. The attacker will only have part of the message.
          • by swillden (191260)

            It's like frequency hopping. The attacker will only have part of the message.

            Right, but that would be a strength, not a vulnerability.

        • You could imagine doing RAID like striping of the data so that if some was lost you could recover. And/or encryption actually. Plus you can always stop using a path if it is doing something evil with the data. Its easy to imagine multi path TCP being more secure than single path TCP. Also imagine a case where you have multiple, untrusted Wifi networks to leach off - with multi path TCP you don't have to worry about them dropping or snooping packets.

      • Security concerns may or may not be relevant. A lot of places have trivial security on their iSCSI between SAN and server, because the security is applied at other levels (segregated switches / airgap, physical security).

        I can think of a number of uses (SAN-server connections where you need more than gigabit) where security is irrelevant.

      • Re: (Score:3, Informative)

        by fleisher (865744) *
        The old saying is, "The proof of the pudding is in the eating," not "The proof is in the pudding."
        • The old saying is, "The proof of the pudding is in the eating," not "The proof is in the pudding."

          Exactly! The OLD saying was "The proof of the pudding is in the eating,"
          The NEW saying is "The proof is in the pudding."

          Language changes - deal.

      • by 0ld_d0g (923931)

        What specific security concerns do you have that don't also apply to existing protocols?

    • by swillden (191260) <shawn-ds@willden.org> on Friday March 22, 2013 @09:17PM (#43253821) Homepage Journal

      RFC 6182 [ietf.org] if anyone is interested.

      I think RFC 6824 [ietf.org], linked in the summary, is the more relevant RFC.

    • by c0lo (1497653) on Friday March 22, 2013 @10:55PM (#43254295)
      For those wanting to try, their install howto [multipath-tcp.org]. Seems supported on:
      1. Linux - either debian binaries or compiling from source. Both kernel module and UserSpace ways.
      2. Virtualized Linuxes - their example is provided for Amazon EC2
      3. Mac OSX - but, obviously, not on iPhone (I estimate slim chances for this to happen in the near future - it's a technology disruptive for the mobile providers income, as it makes the multi-pathing over cell/WiFi hot-spots transparent to end user)
      4. Android (Opinion: see? This is one of the reasons relying on "walled gardens" is bad: you have to wait for the mercy of the garden lord to benefit from something).
  • without every user making 3 connects to view their friends cat picture.

    yes, this could have some good uses, no, dont release it to the drooling masses so 12 year old Tiffany can stream Justin Bieber videos while texting her buddy sitting right next to her "faster".

    • by ebno-10db (1459097) on Friday March 22, 2013 @09:41PM (#43253969)

      Sheesh, you wanna put even more people out of work? More cell bandwidth needed? Ok, more base stations, new and improved protocols, new frequency allocations, etc. etc., etc. As someone who once made a living working on cellular (phy layer) stuff, I say 12 year old Tiffany has both a Constitutional and a God given right to stream Justin Bieber videos while texting her buddy sitting right next to her. I'll even write the manifesto!

      More seriously, a lot of what we take for granted started out as frivolous luxuries. I tell my daughter about days before cell phones, or PC's, and having seven channels of broadcast TV (and having to get up to change the channel!) and she's convinced I come from the age of dinosaurs. She's probably right. That was good, because I made a living changing it.

    • by c0lo (1497653) on Friday March 22, 2013 @09:59PM (#43254049)

      without every user making 3 connects to view their friends cat picture.

      Rest assured: there'll be a single connection using a cell tower. A second flow will be made using the connection with nearby WiFI hot-spot, and Tiffany's chatting to her buddy sitting next to her will be really faster (without quotes); even better, the above will happen without Tiffany knowing or the extra requirement for Tiffany to have a geek father that's not lazy and does have spare time (even if one may wonder what to what good being a geek will be in the future).

      • by Osgeld (1900440)

        probably one who is offended by the idea of a big dongle enough to get a couple real dorks fired

    • If speed is what you are after, the drooling masses is what you have to bet on. Nobody will invest the money needed to give you faster access to your Linux repository, but the ability to sell Joe Washup some porn or Tiffany Teenygirl some videos of the heartthrob du jour, now we're talking.

  • I remember getting dual-channel ISDN, which was 128k, but it was split into two 56k data channels and a 16k control channel. You could never download from any one site faster than 56k because a connection couldn't straddle more than one data channel.

    Still, I could play EQ and surf at the same time on a different computer, a novel thing you young punks take for granted get off my lawn!

    • Re:Don't even! (Score:4, Informative)

      by BitZtream (692029) on Friday March 22, 2013 @11:10PM (#43254375)

      Wow, sucks to be you. ISDN channel bonding was well known and I personally used it to achieve higher speeds than you could on a single channel even over a single TCP connection. The bonding had nothing to do with the modem/circuit actually and in reality was just a standard feature of the PPP protocol called multilink-PPP. You can still do the exact same thing today with multiple connections and pretty much any PPP client on ANY OS on the planet.

      Of course, ISDN is actually 2 64kbps data channels and a 16kbps control channels, as it was meant to carry 2 voice channels, which by standard, are 64kbps data channels, so I'm guessing you really don't know that much about it in general.

    • Your phone company could handle something as fancy and high-tech as ISDN with no need to assemble every tech in the house to prop up the line? Get offa MY lawn!

  • by Anonymous Coward

    Wouldn't six 10 gig connections add up to one 60 gig connection instead of one 50 gig connection?

    • by Zapotek (1032314)
      I assume 10Gbps were eaten by protocol overhead and arbitrary resource restrictions. Perfect distribution/load-balancing is seldom the case in the real world and this does seem like quite an achievement, all things considered. Easy link aggregation at the protocol level, a big thank you to the devs. :)
    • Re:Bad math? (Score:4, Informative)

      by Olivier Bonaventure (2873367) on Saturday March 23, 2013 @04:49AM (#43255495)
      The limit here is the CPU and on the sender and the receiver. Both servers used in the test reached 98% CPU load to achieve 52 Gbps. Note that 52 Gbps is the googput at the application and not the bandwidth used on the links (which is higher due to the various overheads)
  • One of the barriers to this technology will be API support. Many APIs provide the IP address (on both sides) with the connection object. Implementors will have to make a choice about which ip to expose and remain backward compatible.

    • by Anonymous Coward

      No. MTCP is transparent to the application. You can use a normal socket API.

      • IPv6 should be transparent to the application as well, yet still it remains largely unimplemented.
        • Re:API support (Score:5, Informative)

          by Olivier Bonaventure (2873367) on Saturday March 23, 2013 @04:53AM (#43255513)
          Multipath TCP supports transparently IPv4 and IPv6. A Multipath TCP connection can start over IPv4 and then use IPv6 without the application being aware of the utilisation of IPv6. This could help the utilisation of IPv6 paths by IPv6 unaware TCP applications.
          • by funkboy (71672)

            Great idea.

            The fact that the protocol supports this without requiring changes to the applications is pretty impressive.

        • by jgrahn (181062)

          IPv6 should be transparent to the application as well, yet still it remains largely unimplemented.

          From my point of view (Linux), it is largely implemented at the endpoints by now. We just don't have many servers to talk to, and no ISPs willing to sell it to us.

    • Re:API support (Score:4, Informative)

      by c0lo (1497653) on Friday March 22, 2013 @10:20PM (#43254147)
      In my understanding, this will still rely on multiple IP addresses (not using a single IP address for all the network connections). The difference: it will ride on top of multiple TCP/IP connections - assuming they are available - to multiplex their different paths into a single socket connection (that is: no API changes).

      Sort of: if both WiFi and cell channels are available (think: wandering in a shopping mall with public hotspots), one's Android mobile will use both of them in the same time to manage one's plot in Farmville (or to download the MP3's using that magnet from the PirateBay, or placing whatever buy/sell orders on stock exchange); if one walks out of WiFi spot coverage, the mobile will use only what's available - the cell connection.

      Why I used android in my example? Well, it's a Linux kernel, the first implementation is already available. Besides, that should be great news for Google: their "goggles" will be able to transmit what you see much faster and reliable. What I understand from the MCTCP guys' presentation [multipath-tcp.org] makes me believe MPTCP is able to cope with the use and drop from use of multiple dynamically IP addresses (are assigned to the many network devices one's mobile has): thus stepping from one hot-spot to another will not impede Google's capability to receive the data from your (their?) glasses.

      • Re:API support (Score:5, Interesting)

        by CAIMLAS (41445) on Saturday March 23, 2013 @02:22AM (#43255085) Homepage

        Yep. And this is a godsend, in some ways: "multipath NFS" should soon be inexplicably easier to accomplish on a high scale. I will be able to put in a single redundant/HA host with 8 1GBps NICs and not have to worry about setting up multipath on each of the individual VM heads I run. This has the significant advantage of not being stuck with immobile "SAN storage" LUNs or, for that matter, "enterprise" hardware vendors which can't bring the reliability their hardware close to anything near what generic Intel or even bcm network cards can provide.

        All the better if I've got unified storage at the backend with abstracted paths (eg. lustre, unionfs).

        And from the looks of it, it's designed 'forward' - it's going to be MUCH easier to do HA TCP connectivity with this than it is with misc. service level TCP (eg. heartbeat), particularly when you're dealing with (mostly) centrally assigned IPv6 addresses. Awesome.

        Granted, from the looks of it, we may have to wait for switch support first, too... I didn't read that carefully.

        • by c0lo (1497653)
          Coincidence: I'm waiting for my ProLiant N40L G7 MicroServer to be delivered early next week; ordered with 3 WD NAS grade HDD-es (the micro-server: $200. The HDD-es: $450+ all 3)
          Guess for what I'll use it and how I'll be testing MPTCP soon?
        • NFS on multipath is my interest, too.

          In NFS (v4) on TCP, the endpoints frame messages on the bytestream, independently in each direction. As FireFury03 states above, we're basically (potentially large) packet based. We'd like help from new transports in framing those messages optimally, avoiding head-of-line blocking for entire messages.

          In addition to solving HOL, it's been proposed that we could design message framing on SCTP so as to deliver messages and data chunks on different streams, and get some a

          • by c0lo (1497653)

            So do MTCP developers see solutions for any of these problems on the horizon?

            I'm in no way affiliated or knowledgeable in MPTCP - so I may be wrong - but from what I got from their presentation [multipath-tcp.org], MCTCP is not actually designed with the NFS-like usecase in mind (even if it may be used for such), but with the more "common" usecase of a mobile device able to use either/both cellular and WiFI networking.

            The second thing that I saw as peculiar: it is not even supported by a network protocol (like IP is supporting TCP/UDP/SCTP/etc), but is supported by TCP. While it will have to deal someh

            • by patch11 (1303699)

              That is, assuming the head-of-line is send on one path and that path involves a HOL-blocking, then it doesn't matter if the other paths have lower latencies, the entire original stream will be HOL-blocked

              The implementation includes a solution to overcome HOL-blocking by reinjecting the blocking data-segment on the lower-latency path. Have a look at our scientific paper, which explains this mechanism: http://inl.info.ucl.ac.be/publications/how-hard-can-it-be-designing-and-implementing-deployable-multipath-tcp [ucl.ac.be]

              • by c0lo (1497653)

                The implementation includes a solution to overcome HOL-blocking by reinjecting the blocking data-segment on the lower-latency path.

                Have a look at our scientific paper, which explains this mechanism: http://inl.info.ucl.ac.be/publications/how-hard-can-it-be-designing-and-implementing-deployable-multipath-tcp [ucl.ac.be]

                Oh, wow! Thanks.

              • by Monkius (3888)

                Hi,

                Speed-reading the paper, there appears to be some implicit ammunition for the SCTP approach (if it worked!), at least for applications like HTTP, NFS, etc, which are characterized by multiplexing of large and small messages on the stream. I conclude this from section 5.3, which I think states MPTCP over 2 links was slower than ordinary TCP over one link, when message size was 30K.

                (Apologies if I'm misreading.)

                Thanks,

                Matt

                • I conclude this from section 5.3, which I think states MPTCP over 2 links was slower than ordinary TCP over one link, when message size was 30K.

                  For very small flow-sizes (like less than 30KB), MPTCP should not try to create additional subflows. Because, the whole data fits in the initial window of the first subflow. However, at the moment the linux implementation always tries to establish new subflows. In the paper's stress-testing scenario these additional subflows just consumed CPU-cycles and thus the "bad" results for MPTCP with very small flows

                  An easy fix would be to delay the establishment of additional subflows until a certain threshold of da

                  • by Monkius (3888)

                    Thanks, Christoph.

                    I think I was mis-reading, section 5.3 is discussing performance with short-lived connections, such as happens with HTTP .9 or 1.0. The question I would ask next is, how does MPTCP perform when HTTP 1.1 or similar channel multiplexing is used?

                    Matt

                    • We have not yet done extensive experiments with HTTP1.1.

                      But, MPTCP is a benefit for bandwidth-intensive (thus increasing throughput) and long-lived connections (increased resilience against link-failures).

                      So, I would say that HTTP 1.1 would benefit from MPTCP.

                      Cheers,
                      Christoph

    • Re:API support (Score:4, Informative)

      by Olivier Bonaventure (2873367) on Saturday March 23, 2013 @04:52AM (#43255511)
      The current implementation in the Linux kernel only exposes the first address used in the connection to the application. If the addresses change, the application is not informed but the TCP connection remains alive. Exposing addresses to the application is an old mistake of the socket interface. The socket interface does not expose packet losses because TCP deals with them and provides a bytestream abstraction to the application. Multipath TCP does the same, it handles all changes in address transparently to the application.
  • by Anonymous Coward

    I'm possibly missing the point here, but I'm struggling to understand how this would be put to use:
    Servers that can pool multiple high-speed interfaces:
    This capability has been around for years - port channeling/interface bonding/whatever vendors call it, do this already at L2. Aside from making it easier for those interfaces to sit on different subnets, why would you want to push this capability to L3/TCP? Seems like it just introduces additional complexity.

    "Smart" devices (or any client really)
    I suppose

    • Re:Use Cases? (Score:4, Informative)

      by aXis100 (690904) on Saturday March 23, 2013 @12:13AM (#43254677)

      You're missing the point. One of the big reasons to have multiple interfaces is for redundancy - with a company's internet interface, redundancy would be vastly improved by choosing two different providers, and even better with different mediums. The subnets will definitely be different.

      Having both of these links acting simultaneously would be great and I could see a lot of people being excited about it.

      • by c (8461)

        Having both of these links acting simultaneously would be great and I could see a lot of people being excited about it.

        Well, "both" links won't work too well.

        One of the main problems with using your one redundant link as just a regular link is your bandwidth "needs" tend to grow to include some or even all of the bandwidth available from the now non-redundant link. Then not only do you not have a redundant link, but you've doubled your bandwidth requirements and made it that much harder to provision in an e

        • One of the main problems with using your one redundant link as just a regular link is your bandwidth "needs" tend to grow to include some or even all of the bandwidth available from the now non-redundant link.

          Really, in most cases, there's a big difference between "bandwidth needs" and "bandwidth wants". Businesses who normally use a 10Mb connection will frequently limp along on a backup T1 when necessary, without serious problems. Being without an Internet connection is a much bigger problem.

          But then the question frequently comes up: We have an 10Mb connection, and then a 1.5Mb backup connection that sits around doing nothing all day. Can we somehow combine them into a 11.5Mb connection?

          And the answer is g

    • by fa2k (881632)

      It would be great if the SSH connections from my laptop used the reliable ethernet connection when it's plugged in, and seamlessly switched to wireless LAN when it was unplugged. Even better would be if I could put the laptop to sleep and move to a different location, and that the connections would stay open (given, of course, that there was no I/O on them while the computer was moving, and that it was only moving for a reasonably short time). It seems like it *may* be possible to open a new "subflow" even

  • Their use case uses all interfaces on a machine, then they disable some of them. Do you normally WANT to use every and all interface for your traffic? If you're a mobile device, maybe not?

    • by Anonymous Coward

      You disable the ones you do not want to use at any given time.

  • by manu0601 (2221348)
    I understand the application sets up its sockets as usual, and the kernel add TCP extensions for MTCP, and use them to negociate with remote endpoint and startup the subflows. This is transparent for the application, but is there any way it can inspect what is going on? I think about some kind of generalized getpeername(), which would allow the caller to get information about all subflows in use.
  • by jamesh (87723)
    Is anyone making network adapters with a built in programmable processor with an open specification these days? This particular protocol may well be compatible with some of the existing checksum offload implementations but GSO and GRO would seem to need something special especially for multiplexing across streams.
  • So they're able to get 50Gbps out of 6 10Gbps circuits/handoffs/etc... well simple math would say why only 50 and not 60? Ok so it's cool if you want to tell me that I can simultaneously send data to a single destination via wifi and 3/4g, simultaneously being the key word. that part is interesting because in most cases the public address is different. But the article also mentions "servers that can pool multiple high speed interfaces". What? Any decent firewall, switch or server has been providing this f
    • by aXis100 (690904)

      Yes, you are missing a clue.

      If I got 50Gbps out of 6 x 10Gbps links I'd be ecstatic. That's pretty good efficiency considering the sheer throughput processing requited and overheads involved.

      Plus it may be difficult if not impossible to get multiple high speed interfaces via one internet carrier - however what if 3 or 4 fibre providers went past your datacenter? Buy bandwidth from all of them and use them simultaneously and add redundancy.

    • Re: (Score:3, Informative)

      by Anonymous Coward

      You want to send a shitload of data to a destination but it takes too long? Not a problem, throw a couple quad nics in those bitches and bond them up, problem solved providing your network can support the throughput.

      What am I missing?

      This is layer 4 not 2. So long as both endpoints support it, it don't matter where the traffic goes. they can go over entierly different paths. This is doing what you describe, but over the internet. Transparent to the network, and the higher levels of the protocol stack.

  • This would be a dream for small businesses and home users. Have 2-4 DSL/Cable/Wireless WAN ports and one port for your LAN/Router. Plug and play for instant redundant internet at a much higher speed than any one low cost connection could provide.
    • by funkboy (71672)

      NOOOooo...

      Why would you need an appliance for something that can be done in software?!? The only "appliance" you need is an ethernet switch between your residential connection bridges and your firewall.

  • Has anyone actually thought about how The Onipn Network might take advantage of this? This could potentially, or partially, fix one of Tor's biggest problems, which is the inherent low bandwidth due to one single TCP connection via several nodes in a serial manner. If Tor could leverage multiple nodes in parallel into a single connection, this ould certainly make it faster.... And even more anonymous tha it is today.

  • I was doing TCP multipath in 2004 using iptables to get more upstream out of my box at home. I had two 1.5/384 connections and could and up with 768k upstream. All it took was a clever iptables script that marked alternating packets - even and odd if you will - and mangled odd packets to go out one interface, and even packets for the other.

    Obvioulsy, an actual TCP extension for this is going to be more elegant since it's more scalable and easy to deal with, but the idea is not new.

  • by Anonymous Coward

    I find it annoying that my app is disrupted when I leave a Wifi and the (Android) phone needs a few seconds to connect to the #G/4G network. But then it might just to that because it needs to save the power on the network interface.

    But then I'd buy the phone with double or tripple the battery over the slim one anyway. If only they would be available.

  • Waiting to see an apartment full of geeks and gamers rocking 10 cable modems all linked together and splitting the bill.

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