Date: Tue, 29 Jun 2021 11:11:04 +0200 From: Peter Eriksson <pen@lysator.liu.se> To: Rick Macklem <rmacklem@uoguelph.ca> Cc: freebsd-net <freebsd-net@freebsd.org> Subject: Re: RFC: NFS trunking (multiple TCP connections for a mount Message-ID: <362300CE-30DA-4552-A3E4-0F3DFE385B2A@lysator.liu.se> In-Reply-To: <YQXPR0101MB0968DC173855A82AAF45F08FDD039@YQXPR0101MB0968.CANPRD01.PROD.OUTLOOK.COM> References: <YQXPR0101MB0968DC173855A82AAF45F08FDD039@YQXPR0101MB0968.CANPRD01.PROD.OUTLOOK.COM>
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> I don't understand how multiple TCP connections to the same > server IP address will distribute the load across multiple network > interfaces? > I thought that lagg would have handled this? A lagg typically keeps all data in a TCP stream on a specific lagg member (depending on how the lagg is set up, unless you select the “roundrobin” option in freebsd - don’t do that unless you like out-of-order packets…) Network equipment with laggs typically hash the IP streams over the lagg members based on MAC addresses (source&target), IP addresses (source&target) and port numbers. (We have been diagnosing a fun problem locally where we see packet losses/performance drops over our internal backbone network for certain combinations of odd/even IP addresses/port numbers when things pass certain SPB “routers” (which typically hash the streams over many “channels” between routers)… Fun fun. :-) I think the multiple NFS TCP streams could make for some nice performance improvements in certain cases. And it would be a more generalisation of having multiple streams between two hosts - one-or-many over IPv4 and one-or-many over IPv6 at the same time. Windows SMB has a similar feature. Just avoid the Linux NFS mounting deadlock issue with “down” servers please :-) - Peter
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