Ted, On Tue, Aug 25, 2015 at 12:43 PM, Ted Lemon <[email protected]> wrote:
> On Aug 25, 2015, at 11:46 AM, Alia Atlas <[email protected]> wrote: > > ECMP or downstream paths is not a research project; it is common used > technology. When the traffic streams desired are larger than can fit > across a single path, it becomes critical. > > > ECMP in a homenet environment, self-configuring and reliable, is a > research project. > > Figuring out how to handle interfering vs. non-interfering paths is, I > think, orthogonal to ECMP. The multiple links > that might interfere can easily be used for different destinations. While > interesting, that seems like a problem that can needs > solving already. Is that piece of the problem a research project? > Figuring out what links interfere? Is this something that would need > a centralized view of the home network? > > > This is not a problem that a typical end user needs solved. You do not > need ECMP for 4k Netflix. You do not need ECMP to talk to your IoT > devices. You don’t even need ECMP to talk to your homenet file server, in > the currently unlikely event that it’s not in the cloud (that is, in a rack > in a data center outside the home). ECMP might be _nice_ for the unlikely > in-home file server case, but it is not _necessary_. If you think it is, > it’s probably because you are used to low-performance home routers with > bufferbloat, a problem ECMP would not address, and likely would make worse. > We’ve all experienced the home router that, when you try to do a massive > file transfer between two devices, suddenly stops routing anything else > until the transfer is finished. This is not a problem that ECMP would fix. > It depends on link speeds in part. My point was merely that this is a default in link-state routing. It is self-configuring, of course. I was asking to understand the requirements. > What I consider to be a research project are: > > - Figuring out that links interfere > Is this merely the trade-off between using multiple links? I normally assume that some traffic is carried across all links. I am not sure why the concept of using multiple paths is radically different than the basic problem or why you feel it explodes the complexity? > - Figuring out what set of links are candidates for ECMP for a particular > pair of endpoints > In most routing protocols, this is trivial and done. I do believe that there is work to be done for Babel in this space, if it is needed. > - Handling unannounced topology changes > ?? Isn't that what a routing protocol does - detects and distributes the topology change? > To me this is a classic case of premature optimization. Of course > ultimately we’d like this to work. But it’s not even remotely something > that we care about _right now_. If we ship homenet devices that do not do > ECMP, nobody will even notice. > Ted, I asked a question about a feature that is considered critical in every routing environment that I am familiar with. I find it frustrating that looking ahead to significantly more complex home networking topologies and link types, which may be many years out still, is unexceptional, but asking about a feature that allows better use is described as premature optimization. I am asking about a routing requirement. I still am not clear on how link interference is handled for different destinations. Regards, Alia
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