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Suppose I have a switch that supports Gigabit Connections and Auto Uplink. Also, suppose that I have 4 clients (A, B, C and D), each with 100Mbps NIC's connected to the Gigabit Switch such that the max bandwidth from all clients is 400Mbps.

Now I have a server with a 1Gbps NIC connected to the switch. All clients access a resource on the server simultaneously.

My question is, can each client receive the resource on the server @ 100Mbps speed, meaning that there is a total of 600Mbps bandwidth remaining or is the 1Gbps shared over 4 connections?

See drawing for the layout of network.

  • "or is the 100Mbps shared over 4 connections?" I guess you meant '... the 1Gbps shared...' – Everton Feb 9 '16 at 12:35
  • Woops, exactly I meant that, see edit – SergeantSerk Feb 10 '16 at 22:48
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Theoretically you could consume 400 Mbit/s of the server's bandwidth with that setup, provided that everything works perfectly.

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  • In the real world you have packet overhead, problems with the server serving the content fast enough, problems with the clients receiving it fast enough, crappy NICs that can't work at full speed etc. etc. – Stuggi Feb 8 '16 at 20:35
  • Does that mean that the server, assuming perfect conditions, provides 100Mbps equally to all 4 clients? – SergeantSerk Feb 8 '16 at 20:36
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    Yes it would do, as long as all the links in the chain can go that fast, i.e. a cheap switch might have all 1Gbps port but actually they can't all run that fast at the same time, maybe the server hardware isn't fast enough to provide simultaneous data streams on 100Mbps but could do one single stream at 1Gbps etc. If everything works as expect then yes it would work. – jwbensley Feb 8 '16 at 21:03
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My question is, can each client receive the resource on the server @ 100Mbps speed, meaning that there is a total of 600Mbps bandwidth remaining or is the 1Gbps shared over 4 connections?

Link utilization will depend on how applications+protocols work.

For instance, one could have the server trying to send a constant-rate 2Gbps multicast stream that the four clients would like to receive. However, the 1Gbps server link will drop half of the traffic, and receivers' 100Mbps link will only be able to deliver 5% of the original traffic (100Mbps/2000Mbps). And all this while links are running at full capacity.

If however, you are running an web server, and all your traffic is HTTP, the traffic pattern is likely:

  • every client would be limited to its 100Mbps link.
  • the server 1Gbps link would run at most at 400Mbps.
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