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Comment by hansel_der | Hacker News Reader

> Especially if you need multiple hops, fiber is just faster. In my tests, 0.2ms vs 3ms roundtrip time for 10G SPF vs. 10G RJ-45

ime if your unloaded latency on copper ethernet exceeds 0.2ms per hop there is some form of powersaving involved

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If I remember correctly, the IEEE 802.3an line coding overhead is around 2.6ms for each time you switch between SPF+ and RJ-45. That's in line with my measurements.

SPF+ switch to OM3 fiber to SPF+ PCIe card => 0.2ms

SPF+ switch to RJ-45 cable to RJ-45 PCIe card => around 3ms

NAS-[10GbE]->switch-[1GbE]->asus router, 2 hops ping test: ``` yatli@yatao-nas ~ % ping 192.168.50.1 PING 192.168.50.1 (192.168.50.1) 56(84) bytes of data. 64 bytes from 192.168.50.1: icmp_seq=1 ttl=64 time=0.236 ms 64 bytes from 192.168.50.1: icmp_seq=2 ttl=64 time=0.195 ms 64 bytes from 192.168.50.1: icmp_seq=3 ttl=64 time=0.300 ms 64 bytes from 192.168.50.1: icmp_seq=4 ttl=64 time=0.271 ms 64 bytes from 192.168.50.1: icmp_seq=5 ttl=64 time=0.153 ms 64 bytes from 192.168.50.1: icmp_seq=6 ttl=64 time=0.216 ms 64 bytes from 192.168.50.1: icmp_seq=7 ttl=64 time=0.300 ms 64 bytes from 192.168.50.1: icmp_seq=8 ttl=64 time=0.165 ms 64 bytes from 192.168.50.1: icmp_seq=9 ttl=64 time=0.163 ms 64 bytes from 192.168.50.1: icmp_seq=10 ttl=64 time=0.265 ms 64 bytes from 192.168.50.1: icmp_seq=11 ttl=64 time=0.174 ms 64 bytes from 192.168.50.1: icmp_seq=12 ttl=64 time=0.272 ms 64 bytes from 192.168.50.1: icmp_seq=13 ttl=64 time=0.397 ms 64 bytes from 192.168.50.1: icmp_seq=14 ttl=64 time=0.256 ms ^C --- 192.168.50.1 ping statistics --- 14 packets transmitted, 14 received, 0% packet loss, time 13168ms rtt min/avg/max/mdev = 0.153/0.240/0.397/0.065 ms ```

OK it seems mistake was to put a RJ-45 transceiver into an SPF port, if your direct RJ-45 line is so much faster.

Yeah I think so. There might also be better converter modules. Anyway, my setup is caused by an oversight of not burying light pipes into the floor. Otherwise I guess I'll go with SFP+ too. I'm using TP-Link TL-ST1005 which is the cheapest 10GbE switch out there and it cost like $150. Also RJ-45 adapters/switches run anecdotally hotter than SFP+ ones.

either that, or the equipment is in awe because you mixed up its acronym

pretty wild, considering my phone averages at 2.2ms ROUND trip time when pinging the router.

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