Hi,

2.3µs is a typical delay for a 10GBASE-T connection. But fiber or SFP+ DAC
connections should be faster: switches are typically in the range of ~500ns
to 1µs.


But you'll find that this small difference in latency induced by the switch
will be quite irrelevant in the grand scheme of things when using the Linux
network stack...

Paul

2018-03-21 12:16 GMT+01:00 Willem Jan Withagen <w...@digiware.nl>:

> Hi,
>
> I just ran into this table for a 10G Netgear switch we use:
>
> Fiberdelays:
> 10 Gbps vezelvertraging (64 bytepakketten): 1.827 µs
> 10 Gbps vezelvertraging (512 bytepakketten): 1.919 µs
> 10 Gbps vezelvertraging (1024 bytepakketten): 1.971 µs
> 10 Gbps vezelvertraging (1518 bytepakketten): 1.905 µs
>
> Copperdelays:
> 10 Gbps kopervertraging (64 bytepakketten): 2.728 µs
> 10 Gbps kopervertraging (512 bytepakketten): 2.85 µs
> 10 Gbps kopervertraging (1024 bytepakketten): 2.904 µs
> 10 Gbps kopervertraging (1518 bytepakketten): 2.841 µs
>
> Fiberdelays:
> 1 Gbps vezelvertraging (64 bytepakketten) 2.289 µs
> 1 Gbps vezelvertraging (512 bytepakketten) 2.393 µs
> 1 Gbps vezelvertraging (1024 bytepakketten) 2.423 µs
> 1 Gbps vezelvertraging (1518 bytepakketten) 2.379 µs
>
> Copperdelays:
> 1 Gbps kopervertraging (64 bytepakketten) 2.707 µs
> 1 Gbps kopervertraging (512 bytepakketten) 2.821 µs
> 1 Gbps kopervertraging (1024 bytepakketten) 2.866 µs
> 1 Gbps kopervertraging (1518 bytepakketten) 2.826 µs
>
> So the difference is serious: 900ns on a total of 1900ns for a 10G pakket.
> Other strange thing is that 1K packets are slower than 1518 bytes.
>
> So that might warrant connecting boxes preferably with optics
> instead of CAT cableing if you are trying to squeeze the max out of a
> setup.
>
> Sad thing is that they do not report for jumbo frames, and doing these
> measurements your self is not easy...
>
> --WjW
>
> _______________________________________________
> ceph-users mailing list
> ceph-users@lists.ceph.com
> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>



-- 
-- 
Paul Emmerich

croit GmbH
Freseniusstr. 31h
81247 München
www.croit.io
Tel: +49 89 1896585 90
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