10Mbit interfaces on 100Mbit network

weird_dave · 5 Sep 2016 at 08:33

If I have 2 10Mbit devices each connected to a different 100Mbit switch and a cable between the switches, does the data between the switches transfer the data at 10 or 100Mbit? I can't seem to find information on this

I suspect it transfers at 100Mbit, I can't test it tho as I haven't got the devices yet.

NightSt@lk3r · 5 Sep 2016 at 08:35

The switches will be connected to each other at 100Mbit but the transfer of data will only go at 10Mbit due to the devices transferring the data only supporting 10Mbit.

weird_dave · 5 Sep 2016 at 09:00

It still isn't clear to me if the packets between the switches are at 10M or 100M. From what I have read, switches analyse packets and drop bad ones, so they must be buffering, which would allow for retransmission at a higher rate between the switches, but do they?
If they retransmitted at 10MBit they would use 10x the bandwidth than is necessary

bledd · 5 Sep 2016 at 09:02

Switches will connect to each other as fast as they can. So in this case, 100Mbit. So if those devices are talking to each other, the switch ports will be running at 10% of their capacity.

ov_sjo · 5 Sep 2016 at 10:16

It'll be 10 mbps, unless the inter-switch link is over-utilised, which means it could drop below 10 (from those clients).

weird_dave · 5 Sep 2016 at 10:21

I was hoping that would be the case, there will be other (yet to be determined) stuff connected to the switches and sharing the bandwidth of the connection between them.

weird_dave · 5 Sep 2016 at 10:24

ov_sjo said:
It'll be 10 mbps, unless the inter-switch link is over-utilised, which means it could drop below 10 (from those clients).

Really? That would be rubbish

I may have to use 100MBit devices if that is correct.

bledd · 5 Sep 2016 at 10:57

I think some clarification is needed in this thread.

The switches will connect at whatever speed the switch ports are.

So if they are 100Mbit ports, you could have 10x 10mbit devices on each switch and that would fully saturate the connection, assuming they are all maxing out their transfer speeds.

weird_dave · 5 Sep 2016 at 11:17

That's what I was hoping for, I just can't find any document that specifically states it.

ov_sjo · 5 Sep 2016 at 11:40

weird_dave said:
That's what I was hoping for, I just can't find any document that specifically states it.

You won't, it's just the basics of how switches work.

gamesaregood · 26 Dec 2016 at 22:21

The bigger question is why are you even talking about 10Mbit in this day and age :S

Should be getting a nice gigabit switch.

Caged · 26 Dec 2016 at 22:47

Your mistake is to think about link capacity in terms of the speed that frames are sent down the wire, which isn't how it works.

In your scenario the two switches will link together at 100Mbps. The data being transferred between your two 10Mbps devices won't 'speed up' when it arrives at the switches, since that's not what Megabits is a measure of.

DIABLO · 26 Dec 2016 at 23:34

gamesaregood said:
The bigger question is why are you even talking about 10Mbit in this day and age :S

Should be getting a nice gigabit switch.

i agree with the sentiment but why bump 4 month old thread.