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I have a question which might be stupid but I am curious.. I have a simple network: DSLMODEM (192.168.0.1) <> TL-SG108E (192.168.0.30) <> Laptop (192.168.0.54) There are some other devices on the switch and another switch (TL-SG105E) on another room connected directly to the TL-SG108E switch. All connections are with CAT6 cable.
When I ping from my laptop the DSLMODEM I get this reply:
Pinging 192.168.0.1 with 32 bytes of data:
Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
When I ping from my laptop the SWITCH (108E) i get this reply:
Pinging 192.168.0.30 with 32 bytes of data:
Reply from 192.168.0.30: bytes=32 time=7ms TTL=64
Reply from 192.168.0.30: bytes=32 time=4ms TTL=64
Reply from 192.168.0.30: bytes=32 time=4ms TTL=64
The same happens if I ping a TL-SG105E (192.168.0.31) which is also somewhere on the network:
Pinging 192.168.0.31 with 32 bytes of data:
Reply from 192.168.0.31: bytes=32 time=4ms TTL=64
Reply from 192.168.0.31: bytes=32 time=1ms TTL=64
Reply from 192.168.0.31: bytes=32 time=1ms TTL=64
while the devices on the TL-SG105E reply with <1ms:
Pinging 192.168.0.91 with 32 bytes of data:
Reply from 192.168.0.91: bytes=32 time<1ms TTL=64
Reply from 192.168.0.91: bytes=32 time<1ms TTL=64
Reply from 192.168.0.91: bytes=32 time<1ms TTL=64
I wonder why when I ping any of the devices the time is <1ms as I would expect and when I ping the switch it is variable higher than 1ms?? The default gateway on the laptop where I do the pings from is 192.168.0.1 (if that has anything to do with it).
Thanks a lot!
So this is normal and I shouldn't pay any attention for a defective switch? – MerNion – 2017-01-11T13:15:02.487
Right. It's switching just fine. It has a very puny CPU, and its CPU has to do a lot of work to respond to a ping. (Even many high end routers are lousy ping responders and it's not unusual to see fast machines way past the router having faster ping times than the router, even though the traffic goes past the router to the fast machine. They sometimes even drop packets bound for the router while switching billions of them passing though without a hiccup.) – David Schwartz – 2017-01-11T13:15:20.223
Thanks a lot! I can't say for sure but i believe when i first bought them they times were <1ms but maybe i didn't have any other devices connected on them yet.. I can't remember.. – MerNion – 2017-01-11T13:17:36.830
1It can depend on what else the CPU has to do. If you're using its user interface, if it's handling multicast filtering, if it's doing spanning tree, and so on, those things will add jitter and latency to pings. The actual switching of packets is usually handled without the CPU's involvement. – David Schwartz – 2017-01-11T13:19:08.030