What does "it was faster" mean? Higher throughput? Higher latency? Less loss of performance of one data flow when you start another? It could be that you had some major negotiation problem with the switch, and that caused performance problems.
DS
Could someone give me a technical reason why, when I connected a cable modem and three computers to a hub, it was faster than connecting a cable modem and three computers with a switch?
I know that routers are the solution, but I am in a debate and am drawing on my past experience. For example, when using a packet sniffer, you want to be a part of the same collision an broadcast domain. You can do that with a hub, but you can't with a switch.
It must be the same principle when you only have 2 or 3 computers on the same network and collisions are not a problem. Am I right and if I am, could someone explain why?
TIA
From: "RobW"
| Could someone give me a technical reason why, when I connected a cable modem | and three computers to a hub, it was faster than connecting a cable modem | and three computers with a switch? | | I know that routers are the solution, but I am in a debate and am drawing on | my past experience. For example, when using a packet sniffer, you want to | be a part of the same collision an broadcast domain. You can do that with a | hub, but you can't with a switch. | | It must be the same principle when you only have 2 or 3 computers on the | same network and collisions are not a problem. Am I right and if I am, | could someone explain why? | | TIA |
Hubs only retime the signal.
E-switches use active electronic processing electronics and that takes time. That time introduces a latency. The cheap E-switches have higg latency valuse as compared to more expensive E-switches. Thus SOHO Routers and SOHO E-switches have high latencies that will exibit a slightly slowere performace than a hub. This will be more evident on a network with little use. On a more congested network, the E-switch will perform better because of the serparation of collision domains.
I have also see then an auto-switching hub (not a dedicated 100Mb/s or 10Mb/s hub) will also introduce latency as compared with a hub that is a dedicated to 10Mb/s or
100Mb/s.
Simple. Hubs are electrical repeaters, merely reforming and retransmitting waves. They often have a very short delay times, one bit-time or so.
Switches have intelligence. They look at the destination MAC and stuff it out the right port. Expensive commercial switches have a "cut-over" that will start forwarding packets before they are complete. Cheap SOHO equipment is store and forward, nothing gets sent out until the full packet is received, up to 12,000 bit times (1.2 ms at 10Mb/s).
In practice, very rarely is the difference noticeable or important.
-- Robert
Greetings,
This sounds like a simple Duplex neogtiation issue between the Switch and the PC, however there are several possible causes for this....
In practise, there should no difference between using a HUB and a SWITCH with only 3 machines, as long as BOTH the HUB and the SWITCH are operating at the same speed (EG 10Mb/Half Duplex). If there IS a difference, then the most likely cause will be some sort of Ethernet Negotiation mis-match when using the Etherswitch. The simple solution is to turn off auto-negotiation by locking each machine to a fixed configuration that matches the Switch.
A true HUB is only Half Duplex, which is the lowest level of autonegotiation, whereas a switch should be able to operate in both Half and Full Duplex modes. The most common form of performance issues when using Etherswitches is a DUPLEX negotiation mis-match between the ends (Half at one end, Full at the other), and the net effect of this is a DRAMATIC decrease in performance.
Note. Be very careful about some Gigabit Ethernet cards, Gig only has Full Duplex, so when connecting to a lower speed it needs to be able to switch to Half Duplex, expecially when using a Hub. I have heard that when some Gig cards are asked for I know that routers are the solution, but I am in a debate and am drawing on
It depends on the Etherswitch, EG Cisco Switches have a Monitor mode that allow a port to be replicated and monitored, so it is possible, but you have to have the facility in the Etherswitch and know what you are doing....
I hope this helps..............pk.
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