Re: [tcpm] [v6ops] Flow Label Load Balancing
Fernando Gont <fgont@si6networks.com> Thu, 03 December 2020 19:42 UTC
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To: Tom Herbert <tom@herbertland.com>, Erik Kline <ek.ietf@gmail.com>
Cc: Fernando Gont <fernando@gont.com.ar>, IPv6 Operations <v6ops@ietf.org>, tcpm <tcpm@ietf.org>
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From: Fernando Gont <fgont@si6networks.com>
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Date: Thu, 03 Dec 2020 16:40:21 -0300
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Subject: Re: [tcpm] [v6ops] Flow Label Load Balancing
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On 3/12/20 14:30, Tom Herbert wrote: [....] > > There are two apropos statements in RFC6437: > > "There is no way to verify whether a flow label has been modified en > route or whether it belongs to a uniform distribution. Therefore, no > Internet-wide mechanism can depend mathematically on unmodified and > uniformly distributed flow labels; they have a "best effort" quality." > > "From an upper-layer viewpoint, a flow could consist of all packets in > one direction of a specific transport connection or media stream. > However, a flow is not necessarily 1:1 mapped to a transport > connection." > > So building a load balancer, or any other intermediate network device, > that *depends* on the flow label to be consistent for the life of a > transport connection and 1:1 mapped to a transport connection is > contrary to this guidance. We don't need 1:1. We just need 1:N where N is how flows would be aggregated/grouped for the purpose of load-sharing. > The ship has already sailed on this in > deployment, and even if the protocol requirements were to be > sufficiently tightened that would take years to reach full effect and > that would preclude other use cases where modifying the flow label is > useful. If a stable 1:1 mapped identifier for transport ports is > needed in the network layer, it might make sense to create a new HBH > option for that. The above said, I would probably agree that if havinga non-stable FL breaks something, whatever it breaks is probably already broken, since there's not even a checksum to try to detect whether the IPv6 header has been corrupted. > Personally, if I were building a load balancer I'd > use neither the flow label nor transport ports for entropy, I'd look > at using the destination address since 128 bits allows plenty of bits > of entropy, it's consistent per transport flow and always set in an Problem is that if you have two systems that need a lot of banswitdth (e.g., they are transferring file via several TCP connections)< you wouldn't be able to load-share them -- since the result of the hash would be the sme for all TCP connections.... Thanks, -- Fernando Gont SI6 Networks e-mail: fgont@si6networks.com PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492
- [tcpm] Flow Label Load Balancing Alexander Azimov
- Re: [tcpm] [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [tcpm] [v6ops] Flow Label Load Balancing Alexander Azimov
- Re: [tcpm] [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [tcpm] [v6ops] Flow Label Load Balancing Alexander Azimov
- Re: [tcpm] [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [tcpm] [v6ops] Flow Label Load Balancing Brian E Carpenter
- Re: [tcpm] [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [tcpm] [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [tcpm] [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [tcpm] [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [tcpm] [v6ops] Flow Label Load Balancing Joel M. Halpern
- Re: [tcpm] [v6ops] Flow Label Load Balancing Brian E Carpenter
- Re: [tcpm] [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [tcpm] [v6ops] Flow Label Load Balancing Joel M. Halpern
- Re: [tcpm] [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [tcpm] [v6ops] Flow Label Load Balancing Brian E Carpenter
- Re: [tcpm] [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [tcpm] [v6ops] Flow Label Load Balancing Alexander Azimov
- Re: [tcpm] [v6ops] Flow Label Load Balancing Yuchung Cheng
- Re: [tcpm] [v6ops] Flow Label Load Balancing Brian E Carpenter
- Re: [tcpm] [v6ops] Flow Label Load Balancing Alexander Azimov
- Re: [tcpm] [v6ops] Flow Label Load Balancing Brian E Carpenter
- Re: [tcpm] [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [tcpm] [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [tcpm] [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [tcpm] [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [tcpm] [v6ops] Flow Label Load Balancing Mark Smith
- Re: [tcpm] [v6ops] Flow Label Load Balancing Joseph Touch
- Re: [tcpm] [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [tcpm] [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [tcpm] [v6ops] Flow Label Load Balancing Mark Smith
- Re: [tcpm] [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [tcpm] [v6ops] Flow Label Load Balancing Alexander Azimov
- Re: [tcpm] [v6ops] Flow Label Load Balancing Michael Tuexen
- Re: [tcpm] [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [tcpm] [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [tcpm] [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [tcpm] [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [tcpm] [v6ops] Flow Label Load Balancing Erik Kline
- Re: [tcpm] [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [tcpm] [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [tcpm] [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [tcpm] [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [tcpm] [v6ops] Flow Label Load Balancing Brian E Carpenter
- Re: [tcpm] [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [tcpm] [v6ops] Flow Label Load Balancing Fernando Gont