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uk.comp.home-networking (UK home networking) (uk.comp.home-networking) Discussion of all aspects of computer networking in the home, regardless of the platforms, software, topologies and protocols used. Examples of topics include recommendations for hardware or suppliers (e.g. NICs and cabling), protocols, servers, and specific network software. Advertising is not allowed. |
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![]() I'll soon be getting a broadband router for my internet connection, this will almost inevitably have a four port hub built into it. I need more than four ports so I'll use my existing four port hub as well. Presumably I just connect it as follows:- To Internet | Router/Hub | | | | PC PC PC | | | Second Hub | | | | PC X Y Z X, Y, Z are other things like a print server and spare ports. Presumably the PCs won't know any different from when they were all on one hub, they will just see all the devices on the same subnet as they did before. Another question occurs to me now, what happens with auto switching 10/100Mbs hubs, if (for example) all the PCs have 100Mb/s ports but the print server (X) is only 10Mb/s? Does any one 10Mb/s device on the network slow *all* transfers down to 10Mb/s? If not then how does it work because, as I understand it, all packets are broadcast to every device? Single packets could be buffered in the hub and sent out more slowly than they arrive but this would still slow down a long transfer of data. -- Chris Green |
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#3
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![]() Rob Morley wrote: In article , " says... I'll soon be getting a broadband router for my internet connection, this will almost inevitably have a four port hub built into it. I need more than four ports so I'll use my existing four port hub as well. Presumably I just connect it as follows:- To Internet | Router/Hub | | | | PC PC PC | | | Second Hub | | | | PC X Y Z You may need a crossover cable to connect the two hubs, but they will probably have switchable or uplink ports. Yes, OK, my second hub has an uplink port. Another question occurs to me now, what happens with auto switching 10/100Mbs hubs, if (for example) all the PCs have 100Mb/s ports but the print server (X) is only 10Mb/s? Does any one 10Mb/s device on the network slow *all* transfers down to 10Mb/s? Depends if it has store-and-forward buffering or not. If not then how does it work because, as I understand it, all packets are broadcast to every device? If it's not a switching hub then that's how it works. Even if the hub has store-and-forward buffering then surely a long transfer between two 100Mb/s NICs will be slowed down to 10Mb/s by any 10Mb/s device on the same subnet won't it because all the packets will have to be transmitted to that device even though it doesn'e need them. The buffer in the hub/switch will very rapidly fill up long before a large file has been copied between the computers. -- Chris Green |
#4
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![]() wrote in message ... Rob Morley wrote: In article , " says... [snip] Another question occurs to me now, what happens with auto switching 10/100Mbs hubs, if (for example) all the PCs have 100Mb/s ports but the print server (X) is only 10Mb/s? Does any one 10Mb/s device on the network slow *all* transfers down to 10Mb/s? Depends if it has store-and-forward buffering or not. If not then how does it work because, as I understand it, all packets are broadcast to every device? If it's not a switching hub then that's how it works. Even if the hub has store-and-forward buffering then surely a long transfer between two 100Mb/s NICs will be slowed down to 10Mb/s by any 10Mb/s device on the same subnet won't it because all the packets will have to be transmitted to that device even though it doesn'e need them. The buffer in the hub/switch will very rapidly fill up long before a large file has been copied between the computers. AIUI, when a mixture of 10M and 100M devices are attached to some 10/100 hubs, they act like a two port switch connected to a 10M hub (with all 10M devices attached) and a 100M hub (with all 100M devices attached). Alex |
#5
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![]() Alex Fraser wrote: wrote in message ... Rob Morley wrote: In article , " says... [snip] Another question occurs to me now, what happens with auto switching 10/100Mbs hubs, if (for example) all the PCs have 100Mb/s ports but the print server (X) is only 10Mb/s? Does any one 10Mb/s device on the network slow *all* transfers down to 10Mb/s? Depends if it has store-and-forward buffering or not. If not then how does it work because, as I understand it, all packets are broadcast to every device? If it's not a switching hub then that's how it works. Even if the hub has store-and-forward buffering then surely a long transfer between two 100Mb/s NICs will be slowed down to 10Mb/s by any 10Mb/s device on the same subnet won't it because all the packets will have to be transmitted to that device even though it doesn'e need them. The buffer in the hub/switch will very rapidly fill up long before a large file has been copied between the computers. AIUI, when a mixture of 10M and 100M devices are attached to some 10/100 hubs, they act like a two port switch connected to a 10M hub (with all 10M devices attached) and a 100M hub (with all 100M devices attached). Yes, I suppose real 'hubs' are pretty rare nowadays. It may well be that my 100Mb/s 'hub' is really a switch, I haven't actually checked and (outside of this discussion) I've learnt what the difference between a switch and a hub is now. -- Chris Green |
#6
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#8
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![]() In article , "Alex Fraser" says... "Rob Morley" wrote in message t... In article , " says... snip Even if the hub has store-and-forward buffering then surely a long transfer between two 100Mb/s NICs will be slowed down to 10Mb/s by any 10Mb/s device on the same subnet won't it because all the packets will have to be transmitted to that device even though it doesn'e need them. The buffer in the hub/switch will very rapidly fill up long before a large file has been copied between the computers. Each device will only send a limited amount of data before waiting for an acknowledgement from the receiving device. If a slow device hasn't downloaded all of its data from the buffer then the device sending the data will pause, freeing up the switch for communication between other devices. You missed the point I did rather, didn't I :-\ - the OP is talking about communication between two 100M devices, not a 100M device talking to a 10M device. You can't sustain 100M between two 100M devices if all frames must be broadcast to all 10M devices. However, there is no problem if you have switched 10M and 100M segments, because traffic from the 10M/100M devices is stored and forwarded to the 100M/10M devices only when it needs to be. I thought we'd already got past the difference between unswitched and switched hubs, but obviously not. |
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