Re: [v6ops] Flow Label Load Balancing
Fernando Gont <fernando@gont.com.ar> Fri, 27 November 2020 20:52 UTC
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To: Alexander Azimov <a.e.azimov@gmail.com>, Tom Herbert <tom@herbertland.com>
Cc: IPv6 Operations <v6ops@ietf.org>, tcpm <tcpm@ietf.org>
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From: Fernando Gont <fernando@gont.com.ar>
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Date: Fri, 27 Nov 2020 17:52:14 -0300
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Subject: Re: [v6ops] Flow Label Load Balancing
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On 26/11/20 06:34, Alexander Azimov wrote: > Dear colleagues, > > We started discussing an incorrect default behavior, and Tom has already > confirmed that it will be fixed. > > Later the thread turned into an argument if the flow label can be > changed during connection/flow lifetime according to current RFC > documents, though these documents can be updated. This looks a bit weird > for me because I always thought that it is the IETF community's > responsibility to document proper solutions. If something undocumented > but worthy happens in the industry - IETF should catch up. So, I would > like to get back to the discussion of reasons and their safety. > > The general idea of changing the routing path upon network > outage/degradation looks obvious. Getting kind of source-based routing > can significantly reduce the reaction time and improve end-user > experience. The flow label has a perfect match here: transparent for the > application, set by the source, not part of 5-tuple, while it can be > used in the load balancing. If you have two links, then, upon change of the FL, you have 50% change that the path will be different -- not good. What would you do if the failure continues? -- keep changing the FL? > Let say that the flow label is a hash of values from the IP packet's > 5-tuple and random number. Then > > 1. In the case of SYN or SYN-ACK retransmission flow label SHOULD be > recalculated. This one MUST be switched of by default, too. (along with #2). > 2. In the case of RTO timeout expiration in the established TCP session > the flow label MAY be recalculated. This setting MUST be switched off by > default. > 3. Otherwise flow label SHOULD be preserved unchanged. > > The first point stands for redirecting connection from the degraded path > before the connection is established, and it looks safe. The second one > can also improve performance if it is set on the server-side. Please > comment if you see security flaws in such a design. At the very least, one should analyze the case where in #1, a packet gets delayed, you change the FL and retransmit, and finally you get a response to the original packet (and/or to both packets). Thanks, -- Fernando Gont e-mail: fernando@gont.com.ar || fgont@si6networks.com PGP Fingerprint: 7809 84F5 322E 45C7 F1C9 3945 96EE A9EF D076 FFF1
- [v6ops] Flow Label Load Balancing Alexander Azimov
- Re: [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [v6ops] Flow Label Load Balancing Alexander Azimov
- Re: [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [v6ops] Flow Label Load Balancing Alexander Azimov
- Re: [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [v6ops] Flow Label Load Balancing Brian E Carpenter
- Re: [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [v6ops] Flow Label Load Balancing Joel M. Halpern
- Re: [v6ops] Flow Label Load Balancing Brian E Carpenter
- Re: [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [v6ops] Flow Label Load Balancing Joel M. Halpern
- Re: [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [v6ops] Flow Label Load Balancing Brian E Carpenter
- Re: [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [v6ops] Flow Label Load Balancing Alexander Azimov
- Re: [v6ops] [tcpm] Flow Label Load Balancing Yuchung Cheng
- Re: [v6ops] Flow Label Load Balancing Brian E Carpenter
- Re: [v6ops] Flow Label Load Balancing Alexander Azimov
- Re: [v6ops] Flow Label Load Balancing Brian E Carpenter
- Re: [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [v6ops] Flow Label Load Balancing Tom Herbert
- Re: [v6ops] Flow Label Load Balancing Mark Smith
- Re: [v6ops] Flow Label Load Balancing Joseph Touch
- Re: [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [v6ops] Flow Label Load Balancing Mark Smith
- Re: [v6ops] Flow Label Load Balancing Fernando Gont
- Re: [v6ops] [tcpm] Flow Label Load Balancing Alexander Azimov
- Re: [v6ops] [tcpm] Flow Label Load Balancing Michael Tuexen
- Re: [v6ops] [tcpm] Flow Label Load Balancing Tom Herbert
- Re: [v6ops] [tcpm] Flow Label Load Balancing Fernando Gont
- Re: [v6ops] [tcpm] Flow Label Load Balancing Tom Herbert
- Re: [v6ops] [tcpm] Flow Label Load Balancing Fernando Gont
- Re: [v6ops] [tcpm] Flow Label Load Balancing Erik Kline
- Re: [v6ops] [tcpm] Flow Label Load Balancing Fernando Gont
- Re: [v6ops] [tcpm] Flow Label Load Balancing Tom Herbert
- Re: [v6ops] [tcpm] Flow Label Load Balancing Fernando Gont
- Re: [v6ops] [tcpm] Flow Label Load Balancing Tom Herbert
- Re: [v6ops] [tcpm] Flow Label Load Balancing Brian E Carpenter
- Re: [v6ops] [tcpm] Flow Label Load Balancing Tom Herbert
- Re: [v6ops] [tcpm] Flow Label Load Balancing Fernando Gont