1 Gbps link autonegotiation

[romansoft]

I connected an uplink wire between my router (ASUS AC68U) and a TPLink SG1008D (unmanaged) switch. Both switches support 1Gbps (1000FD) speed but I'm only getting 100 Mbps (100FD). Why? Before you tell me the wire is the problem, let me explain some details of my network setup and some tests I did.

Router and switch are placed at different rooms at home. I have one network point in one room (where router is) and another network point in the other one (where TPLink is). Both router and TPlink are connected to their respective network points with CAT6 wire (straight). Finally, there is a wire (CAT5e) connecting the two network points (inside the walls at home, aprox. 50m long).

The scheme is:
Router Asus <--CAT6--> Network point #1 <-----CAT5e-----> Network Point #2 <--CAT6--> TPLink

If I use a network tester between two network points, all 4 pairs in RJ45 are ok, I mean, all 4 pairs (needed for 1 Gbps link) are Ok.

Another test: if I connect my laptop instead of TPLink switch, I got a 1 Gbps link (using the same network "circuit" I schemed). So it seems wiring is ok.

BUT if I connect TPLink switch (to network point #2), the link cannot autonegotiate to 1Gbps (so falls down to 100 Mbps speed).

Why?????

Last test I did was moving TPlink to the same room where I have Asus router and connect them directly with one wire, which worked ok (1 Gbps).

So it seems there may be some problem with CAT5e wire, but still cannot explain why the same wire works perfectly (1 Gbps) if I connect my laptop to it instead of TPLink switch (remember all equipment -router, tplink and laptop- is of course 1 Gbps). Apart that my tester said all 4-pairs are working.

Perhaps router and / or Tplink are checking impedances and are more sensitive than my laptop's NIC?

I also tried to force the router to go for 1 Gbps (with robocfg command). It didn't work (no link then). I cannot force Tplink since it's unmanaged :-/

Finally I'm thinking of buying a (cheap) managed TPLink (SG108E model - http://www.amazon.es/TL-SG108E-1000Mbps-Garant%C3%ADa-supervisi%C3%B3n-priorizaci%C3%B3n/dp/B00JKB63D8) and then forcing also switch interface to 1 Gbps.

Am I missing something? Any other ideas?

Hope you can help me. Seems like a good challenge.

Cheers.

 

[bill001g]

Likely your problem is the ends of the wire are connected just good enough to test with the tester but not quite good enough to pass data. You switch may not be able to tolerate the cable but you pc can. Unfortunately the device to really test cable is outside the price range of most people. Even to rent them is really expensive.

All you can really do is reterminate the cables and hope to get lucky. The wall jacks tend to be easier to try over and over unlike rj45 you have to cut it off and throw it away.

 

[romansoft]

Which kind of checks do a switch perform in order to test quality of the 4 pairs of a wire? Any URL / info about that?

Do you think buying a managed switch and forcing interface link to 1 Gbps may work? I mean, would the trick bypass former "quality"-checks?.

Likely your problem is the ends of the wire are connected just good enough to test with the tester but not quite good enough to pass data. You switch may not be able to tolerate the cable but you pc can. Unfortunately the device to really test cable is outside the price range of most people. Even to rent them is really expensive.

All you can really do is reterminate the cables and hope to get lucky. The wall jacks tend to be easier to try over and over unlike rj45 you have to cut it off and throw it away.

 

[bill001g]

The switch sends a pattern of electrical signals over the wire and decides what speed it should run. This is done by the chips themselve.

Generally you would need to force both ends to 1g and if they detected some kind of error they would just not work rather than drop to 100m. It almost has to be the wire but I suppose you could to see if the switch was defective by using a very long cable in the same room.

 

[romansoft]

Finally solved the issue by replacing the switch (old TP-Link) by a brand new Netgear GS108Ev3 (35 eur only).

I chose that model from Netgear 'cause it's a (semi)managed switch so the idea was to force the interface to 1 gbps speed (and doing same at the router side). To my surprise, the switch permits to force speed to 10 and 100 but not to 1000 (!!!!!!). BUT anyway, it solved the problem because it autonegotiated the interface to 1gbps (same as when connecting my laptop and different from my old switch's behaviour).

My plan B was to try out with another (cheap) switch: TP-Link TL-SG108E. It's also (semi)managed, and it permits also forcing interface speed (this time including 1000, I think).

I still don't think my old switch was defective, but maybe it has different "sensitivity" during auto-negotiation in a way it wasn't favorable to me.

Thank you @bill001g for your responses. Very much appreciated.

 

[romansoft]

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