nanog mailing list archives
Re: interesting troubleshooting
From: Saku Ytti <saku () ytti fi>
Date: Sat, 21 Mar 2020 09:58:55 +0200
On Sat, 21 Mar 2020 at 04:20, Steve Meuse <smeuse () mara org> wrote:
What that large flow in a single LSP? Is this something that FAT lsp would fix?
No. FAT adds additional MPLS label for entropy, ingressPE calculates flow hash, based on traditional flow keys and injects that flow number as MPLS label, so transit LSR can use MPLS labels for balancing, without being able to parse the frame. Similarly VPN provider could do that, and inject that flow hash as SPORT at the time of tunneling, by looking at the inside packet. And any defensive VPN provider should do this, as it would be a competitive advantage. Now for some vendors, like Juniper and Nokia transit LSR can look inside pseudowire L3 packet for flow keys, so you don't even need FAT for this. Some other like ASR9k cannot, and you'll need FAT for it. But all of this requires that there is entropy to use, if it's truly just single fat flow, then you won't balance it. Then you have to create bias to the hashResult=>egressInt table, which by default is fair, each egressInt has same amount of hashResults, for elephant flows you want the congested egressInt to be mapped to fewer amount of hashResults. -- ++ytti
Current thread:
- Re: interesting troubleshooting, (continued)
- Re: interesting troubleshooting Job Snijders (Mar 20)
- Re: interesting troubleshooting Christopher Morrow (Mar 21)
- Re: interesting troubleshooting Brandon Martin (Mar 24)
- Re: interesting troubleshooting William Herrin (Mar 20)
- Re: interesting troubleshooting Saku Ytti (Mar 20)
- Re: interesting troubleshooting Matthew Petach (Mar 20)
- Re: interesting troubleshooting Saku Ytti (Mar 21)
- Re: interesting troubleshooting Matthew Petach (Mar 22)
- Re: interesting troubleshooting Matthew Petach (Mar 20)
- Re: interesting troubleshooting Chris Adams (Mar 20)
- Re: interesting troubleshooting Steve Meuse (Mar 20)
- Re: interesting troubleshooting Saku Ytti (Mar 21)
- Re: interesting troubleshooting Mark Tinka (Mar 21)
- Re: interesting troubleshooting Saku Ytti (Mar 21)
- Re: interesting troubleshooting Mark Tinka (Mar 22)
- Re: interesting troubleshooting Saku Ytti (Mar 22)
- Re: interesting troubleshooting Mark Tinka (Mar 22)
- Re: interesting troubleshooting Saku Ytti (Mar 22)
- Re: interesting troubleshooting Mark Tinka (Mar 22)
- Re: interesting troubleshooting Saku Ytti (Mar 21)
- RE: interesting troubleshooting adamv0025 (Mar 23)
- Re: interesting troubleshooting Tassos Chatzithomaoglou (Mar 21)
- Re: interesting troubleshooting Saku Ytti (Mar 21)