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Forum Discussion

tomjam's avatar
tomjam
Aspirant
Mar 12, 2021
Solved

Command "speed 1000 full-duplex" not accepted

Hi We've got the cumbersome network setup that lots of the old network cables in our in-house cabling are split up into two separate RJ45 plugs on both sides (2 links over one cable, each using 4 wi...
  • schumaku's avatar
    Mar 12, 2021

    Hi Tom,

     


    tomjam wrote:

    We've got the cumbersome network setup that lots of the old network cables in our in-house cabling are split up into two separate RJ45 plugs on both sides (2 links over one cable, each using 4 wires).

    ...

    When I add the setting

    speed 100 full-duplex

    the link is instantly up, but I don't want it to be only 100 mbps.


    On shared cables, with just two pairs [four cables aren't sufficient!], there is no other choice - Fast Ethernet (100 Mb/s) is the max you can do on such a cumbersome infrastructure. Anything above is simply impossible. The only other opiton is 10 Mb/s only - very rare except on some IoT or building control devices - and these switchs don't support it.

     

    Would not wonder one second if this makes the automatic speed negotiation on MultiGig up to 10G hard if not impossible ... as you experience.

     


    tomjam wrote:

    The documentation of our M4300 switches list the following syntax for the speed command:

    speed {auto {10G | 5G | 2.5G | 1000 | 100} [half-duplex | full-duplex] | {10G
    | 5G | 2.5G | 1000 | 100} {half-duplex | full-duplex}}

    What seems to be implemented seems to be the max. allowed link speed on the automatic negotiation - to keep the link speed lower to remain within a certain connection quality. The first part of the BNF above appears to have something like this in mind 8-) ... but I suspect this definition isn't correct at all.

     


    tomjam wrote:

    Which means it should be possible to execute:

    speed 1000 full-duplex

    But this syntax is not accepted (value 1000). It only works when I add the "auto" parameter which in turn adds the 30s delay until the link is detected.


    Negative: IEEE specs require automatc speed negotiation for Gigabit and up - my old developer heart would consider to understand this BNF as valid:

    speed {auto {10G | 5G | 2.5G | 1000 | 100} [half-duplex | full-duplex]} | {100 {half-duplex | full-duplex}}

     
    LaurentMa your turn please 8-)

    Regards,
    -Kurt

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