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Alexander Torres
Beginner

Why use 1Gbps fiber port over a 1Gbps Ethernet port?

Say I have two switches and I want to connect them together. Both are capable of 1Gbps speeds and both are Layer 2 only switches. And no VLAN setup either. I install an SFP 1 Gigabit interface transceiver on both switches. Since the switch is already 1 Gbps capable, what benefits do I gain by connecting both switches together via SFP using fiber optic vs connecting them together via any port using a cat6 cable?

Also, if I install two SFP 1 Gigabit interface transceiver on each switch and connect them together, does that then give me 2 Gbps on each side?

Thank you. Best regards,

Alex

1 ACCEPTED SOLUTION

Accepted Solutions

Alex

As long as the copper ports are not oversubscribed then yes you should be fine.

If they are oversubscribed though it could make a difference in terms of performance.

As long as everything is working then I can't see an issue with what you have.

Jon

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4 REPLIES 4
Jon Marshall
VIP Community Legend

Alex

Things to consider -

1) distance between the switches is a key one and this may dictate what you can use eg. in buildings cable drops between the floors can often exceed the maximum distance of copper.

2) cost - copper is a lot cheaper

3) copper can be more susceptible to electromagnetic interference

In addition the uplink ports on switches usually run at wirespeed where the standard ports may or may not.

All that said if everything was equal then yes you could use copper ports to interconnect your switches.

If you installed two connections one of the links would block on a per vlan basis, assuming you were running an STP variant of PVST.

If you wanted them both to pass traffic then you can make an etherchannel which is a logical link containing a bundle of physical links.

STP sees the etherchannel as one link so it can use both physical links.

This does not necessarily give you 2Gbps though. It's to do with how the switch load balances traffic across the links and it's a bit complicated but a quick example -

a client is sending 1.5Gbps to a server. Because the client's mac address/IP address and the servers mac address/IP address remain the same the switch will only use one of the links ie. it will not spread the traffic across both links.

two clients are each sending 750Mbps to a server. Because the clients are different in terms of mac/IP then the switch could put each clients traffic on a different link as long as you were load balancing on source mac or IP address.

Note that on some switches it is not just the mac address/IP address that can be used to select a link.

I was just keeping the example relatively simple.

Jon

Thank you for the good information.

Basically, I have two rooms next to each other. Each room has 5 servers and one switch in each room. The two switches/rooms are connected to each other via cat6 cable and all works well. The reason for my questions is that I see both switches support SFP 1 Gigabit interface transceiver and was wondering if that would make any difference? I imaging that sticking with cat6 would be best in this situation since the switches are less than 30 ft from each other, correct?

Thank you.

Alex

Alex

As long as the copper ports are not oversubscribed then yes you should be fine.

If they are oversubscribed though it could make a difference in terms of performance.

As long as everything is working then I can't see an issue with what you have.

Jon

View solution in original post

Chris Carlson
Enthusiast

your talking about stacking the switches right? what model are these?