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qatar2022
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Auto Negotiation

Thu Mar 16, 2023 7:20 am

Dear all
I have 2 Mikrotik Router (MikroTik RB5009UG+S+ and MikroTik RB5009UPr+S+) the first one I set it up as hotspot DHCP server located in grand floor and the secund one I set it up as a switch located in first floor and I connect them with cat6 cable but the speed on MikroTik RB5009UPr+S+ (100M) only I supposed to get 1GB because auto negotiation is enable on both devices and if I make any change on advertise I can't connect to internet and even on devices as well
any help please

with regards
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mkx
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Re: Auto Negotiation

Thu Mar 16, 2023 8:37 am

The RB5009, configured as switch, indicates that link partner is advertising speeds 10Mbps and 100Mbps. There are 3 possibilities (I'm listing them in order of probability, but you may want to check them starting from the simplest check towards the complex ones):
  • The cable connectors are iffy ... if connectors are at one edge of tolerances and device connector is on the other, then connection can be iffy. 1Gbps requires use of all 4 wire pairs while for 100Mbps (and 10Mbps) only two pairs are used. If one wire of "additional" pairs is not OK, autonegotiation for 1Gbps will fail and link partners will see as if the other end doesn't advertise 1Gbps.
  • cable is terminated non-properly. Either on patch panel or in connectors. Cable has to be terminated in the same way on both ends. There is a standard of doing it with two variants (TIA/EIA 568 A and B) and it's critical to follow the same variant on both ends of cable.
    Additionally, if the cable is shielded (STP) - which is a good thing if cable is longer - then the shield should only be grounded (connected to STP connector shield or to patch panel ground) on one side. If the shield is grounded on both ends, stray currents may flow and those can cause more interference in data wires than unshielded (UTP) cable may pass.
  • The cable itself is either too long or not properly wired. Maximum distance for ethernet is 100 metres (sometimes it works over slightly longer distances but that's not guaranteed). If wire pairs are untwisted over distance longer than a centimetre or two (in patch panels or wall outlets), then the quality degrades considerably ... possibly to the level when high frequency signals, needed for 1Gbps, don't pass through such wires.
  • link partner is set to only advertise 100Mbps and 10Mbps.
  • and then there's always possibility of device being broken. As it's PoE-capable, the possibility is higher than with non-PoE variant due to additional elements, needed for PoE to work on each RJ45 port.
 
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qatar2022
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Re: Auto Negotiation

Thu Mar 16, 2023 8:25 pm

Dear @mkx
I would like to think you for your help and support regarding port speed and auto negotiation
after I read your reply I found one end of ethernet cable on A mode and the other end on patch panel on B mode and I change it to all B mode and the port speed reach to 1g and I can tell you that after solving this issue I reach up to 965Mbps

thanks agene
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