Question My first switch, which switch

[Atari2k]

Good evening,

In my current home/office set-up I've directly connected, through ethernet cables, a router, on loan from my ISP, to my computer, my server and my NAS. I want to update my LAN network to 10Gbit and I'm getting 3 new 10Gbit ethernet PCI cards for my peripherals. Since the router is condemned to 1Gbit ethernet, I wonder what kind of switch do I need to get so that my computer, my server and my NAS can talk to each other directly using the improved 10Gbit speed.

 

[Atari2k]

Perhaps a sketch can help: https://1drv.ms/b/s!AodAwqv_X22EkTewXNQffBFEoFkb?e=03bs0j

 

[bill001g]

Be sure you actually calculate the rates your equipment can do. Many times the disk subsystem will be the bottleneck. It gets extremely expensive to get disk systems that can actually transfer data consistently at 10gbit. Many times these are using raids and SSD devices rather than magnetic media.

It is pretty much that simple. You buy a unmanged switch that has 10gbit ports on it. These are kinda expensive compared to the more common 1gbit device.

Most switches support multiple speeds on the ports so you just plug the router in and it will drop back to 1gbit while the other ports runs at 10g.

Read the fine print though. First be sure the ports will run at 1gbit and 10gbit, most do unless they are SFP based. Next try to find the total switch backplane speed. On your more common 1gbit switch every port can send 1gbit and receive 1gbit all at the same time. So a 5 port switch would have a backplane speed on 10gbit.

Almost every 1gbit switch can run this fast. 10gbit is a lot more bandwidth and not all switch can do it. There really is no case where every port is sending and receiving at max rate on every port but you need to know this might be a limitation. But a 5 port switch that could do say only 50gbit rather than 100gbit would be ok

 

[Atari2k]

thank you for the detailed message, it does answer several points.

The backplate speed is the overall bandwidth that the switch is able to handle? For instance, looking at the specs of the Netgear XS505M, here the link, it reports the Fabric as 100 Gbps, is this the backplate speed? Or how do you figure it out?

Another more theoretical silly question: having a switch in between, how do two peripherals, say A and B, can communicate to each other without hopping through the router? I'd imagine that if A wants to talk to B, A should send packets/frames with both the IP and MAC address of B, so that the switch can forward the traffic. But how can A know the MAC address of B ?

 

[bill001g]

Some vendors use the word fabric. Backplane is a term more used on larger switches with multiple interface cards. But that switch can run all ports are full rate simultaneous. It seem the cheaper technology is getting better and better.

The key thing to know is when you are talking between devices on a LAN,ie subnet, you do not actually use IP addresses. They only use the IP address very early on in the session, kinda like dns does to translate a name to a IP. They use a command called ARP that sends out a broadcast asking who is using IP x.x.x.x.
They switch sends broadcast messages to every port. The end device gets this broadcast and responds with its mac address. In the process the switch itself see which port the mac address is on and keep that in its take. That is how the switch know how to directly send traffic between 2 mac addresses.
Although the data might have ip addresses in it the actually communication between end device on a switch is purely though mac addresses.

You do not even need a router for a lan. If you were to manually assign IP or let everything use self assigned 169.254.x.x ip you can run without any router or dhcp server.