I'm doing my homework and I don't understand this question. If anyone can help me solve or point me in the right direction would be much appreciated.

The question is: If I have a 1Gbps NIC, 100Mbps Router, and a 10Mbps switch, whats the fastest speed I can get in my LAN setup?

  • Is the 1Gbps NIC connected to the router or the switch? – Ramhound Feb 3 '16 at 18:34
  • Im assuming they are all interconnected. If anything can I have your opinion on it? – xtremeslice Feb 3 '16 at 18:36
  • If by LAN, you mean not WAN, then I believe the answer is 100Mbps. You would only get 10Mpbs on the WAN because of the limited speed of the switch, which I'm assuming is synonymous with bridge.l – BillDOe Feb 3 '16 at 18:38
  • Just to be nastyu: almost unlimted LAN speed to localhost. – Hennes Feb 3 '16 at 18:40
  • 1
    @xtremeslice If you have to go through the switch to get to the router, how will you get 100Mbps to the router? – David Schwartz Feb 3 '16 at 19:19

The fastest your link will be, is always the slowest device along the path of travel because it's the culprit of the bottleneck. Assuming you were connected like Router > Switch > PC.

Excuse my excellent art skills trying to demonstrate what I mean.

enter image description here

  • I suspect that this is what they wanted to ask. But as currenly asked to speed is higher. (much higher to 127.1) – Hennes Feb 3 '16 at 18:52
  • @Hennes yeah I get the loopback point. But the point of LAN is interconnecting more than one device. So you'd be sending data from client A to client B, rather than just back to yourself. Also cable modem is supposed to be a switch. The art I found didn't have a switch, but that looked close enough. – DrZoo Feb 3 '16 at 19:00
  • Sort of. A cable modem is supposed to be a modem. It is not the same as a single device with three devices in one (modem to fribre or cable, WAP and router). But I guess many people no longer make that distinction. – Hennes Feb 3 '16 at 19:20
  • -1 If you have a 100Mbps link to a 10Mbps link, data still travels at 100Mbps over the 100Mbps link. It will just only do it 1/10th of the time. – David Schwartz Feb 3 '16 at 19:22

Guessing a bit I read this as follows:

I got a 1 meter (100cm) radius pipe connected to a 10cm big pipe connected to a 1 cm pipe. What is the most water I can push though it?

(The answer matches the 1cm pipe).

And if they are trying to be smart: they toss aside the 10Mbit/sec switch (an antique!) and connect the NIC directly to the router. But that requires context not mentioned in the OP.

  • Thanks! So the answer is 100Mbps because the 1Gbps can handle anything up to 1G and 100Mbps was the highest offered. Thanks for the help! – xtremeslice Feb 3 '16 at 18:43
  • @xtremeslice - No; I would think the answer would be, 10 Mbps, since the switch is part of a Local Area Network (LAN) instead of a Wireless Area Network (WAN). – Ramhound Feb 3 '16 at 18:47
  • Aye. It depends on how you build it. (also see my cheat answer for localhost). Not enough info. – Hennes Feb 3 '16 at 18:48

The question is badly worded - the answer is indeterminate unless you know how many ports there are on the switch.

The answer is probably 100 megabits, as even basic routers have 4 LAN ports on them, so connecting 2 devices into those ports directly will allow 100 megabit connectivity between them.

The answer they are probably looking for is 10 megabits, which assumes that only 2 ports on the router are in use, and all the devices are plugged into the 10 megabit switch. This is a really dumb way of wiring things up.

I guess the point is to test that the student knows the slowest device in the path defines the maximum throughput.

  • But that is false. The slowest device in the path defines the maximum sustained throughput, but the fastest link in the path defines the fastest speed in the setup, which is what the question asks for. – David Schwartz Feb 3 '16 at 19:25
  • @DavidSchwartz - not sure how what you said differs from what I said. – davidgo Feb 3 '16 at 23:52
  • The questions asks what the fastest speed is, not what the total throughput is. The fastest speed is the speed of the fastest part, not the slowest. – David Schwartz Feb 4 '16 at 0:05


The highest speed you can get is to connect the 1Gbps NIC to the 100Mbps router. That link will transfer data at 100Mbps. There is no way to get a higher speed anywhere in the LAN setup with those parts.

  • That would be changing the setup of the LAN they are given. 10 Mbps would be your max. – DrZoo Feb 3 '16 at 19:31
  • No setup is given. We're just told what components they have and asked what the maximum speed is. – David Schwartz Feb 3 '16 at 19:32
  • What kind of weird LAN would directly connect into a router with no switching capabilities? That sounds like a useless LAN to me. – DrZoo Feb 3 '16 at 19:36
  • @DrZoo There's nothing unusual about such a LAN. In fact, a typical SoHo setup with a separate router and modem has just such a LAN between the router and the modem. Consider any network link that serves a single end station. – David Schwartz Feb 3 '16 at 19:39
  • Yes, but this is a networking class where they use the routers that don't have the built-in switching, or X amount of LAN ports like home routers. – DrZoo Feb 3 '16 at 19:47

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