Daisy chaining switches

[Lucavicini]

Hello,
Here is my problem.
I have two PCs with gigabit ethernet interfaces.
When the two are connected trough the same switch (a Gigabit ethernet switch) the transfer speed is roughly 600 megabit/s.
When the two PCs are connected through 2 switches the speed drop to 98 megabit/s. I cannot really explain this as there are no other devices connected to this test network.

PC1 <---> Switch1 <---> Switch2 <---> PC2

The only explanation that I can give is that for an obscure reason the two Switches negotiate a speed of 100Mbit/s instead of 1Gbit/s.

Any explanation for this behaviour?
Cheers
Luca

 

[bill001g]

That would be my guess also. Almost all switches do not delay the traffic at all anymore. With only 2 devices if the port was 1g between the switches it should easily be able to transfer at similar speeds to 2 ports on the same switch. If you were to get very technical there is a slight extra delay because it must take the packet from the memory buffer and transmit it 2 times rather than one in the path but this delay is in MICRO seconds not even 1ms.

Not sure how you would find out or force the speed on a non manageable switch

 

[Lucavicini]

Hi Bill,
Thank you for the answer. I will try an experiment. I always connect devices with straight cables. Nevertheless in theory you should always interconnect switches with cross cables. I will try to change the cable...

 

[Lucavicini]

Using a cross cable between the two switched didn't help: same speed. What a nightmare :-(

 

[NETOPS25]

Try hardcoding the speed and duplex on the trunks of the switches.

 

[NETOPS25]

Try hardcoding the speed and duplex on the trunks of the switches.

 

[Lucavicini]

Hi Netops25,
Unfortunately they are cheap unmanaged switches. I cannot hardcode the interface.

 

[Lucavicini]

Found the answer!!!
The problem was related to one of the PC. By hardcoding the interface speed the transfer speed increased dramatically. That is not explaining why the PC was negotiating speed with the switch sometime at a 100Mbit/s and other times at 1Gbit/s

 

[NETOPS25]

So close ......