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Gigabit Stepping down to 100mbit, fixed by power cycle, cable switch

Head in the Cloud

Gigabit Stepping down to 100mbit, fixed by power cycle, cable switch

I have this odd thing Ive seen throughout my network, different devices. I even saw it overseas at a house I stayed in. 

 

I perfectly good gigabit connection somehow starts only transmitting at 100mbit. Link speed just starts reporting 100mbit. Usually if a cable is detected as bad I am pretty sure the spec is meant to downgrade it to 10mbit half duplex. But thats not whats happening. Anybody seen this? Oxidation? Just a normal thing that happens? 

Networking geek since high school where I got half of a CCNA. Played Marathon II and Infinity over localtalk.
Made many a network over the years, now de facto admin of a retreat center with some of this fine Meraki hardware.
Fortune 100 Tech veteran/refugee.
12 REPLIES 12
Kind of a big deal

Re: Gigabit Stepping down to 100mbit, fixed by power cycle, cable switch

@cmr , you commented on something similar whereby you were seeing same behave which was resolved by swapping out cables?

Darren O'Connor | uccert.co.uk
https://www.linkedin.com/in/darrenoconnor/

I'm not an employee of Cisco/Meraki. My posts are based on Meraki best practice and what has worked for me in the field.
Kind of a big deal
Kind of a big deal

Re: Gigabit Stepping down to 100mbit, fixed by power cycle, cable switch

Indeed @UCcert, we have seen dirty contacts or kinked/damaged cables dropping 1Gb connections to 100Mb, and then sometimes fluctuating.  More common on longer cable runs (30m+)

Head in the Cloud

Re: Gigabit Stepping down to 100mbit, fixed by power cycle, cable switch

ok great. figured as much.

Networking geek since high school where I got half of a CCNA. Played Marathon II and Infinity over localtalk.
Made many a network over the years, now de facto admin of a retreat center with some of this fine Meraki hardware.
Fortune 100 Tech veteran/refugee.
Kind of a big deal

Re: Gigabit Stepping down to 100mbit, fixed by power cycle, cable switch

There is also something called EEE (Energy Efficient Ethernet) that allows devices to step down the link speed to save power.  Some printers do this when in power save mode, and some notebooks do this when running on battery.

It is also common for desktops and notebooks when they go into standby mode.

Head in the Cloud

Re: Gigabit Stepping down to 100mbit, fixed by power cycle, cable switch

I usually see Gigabit connections going down to 10Mbps half when a pc goes into sleep mode but they go back up to 1 Gigabit when the device wakes up.

Sometimes you can send the magic packet to let the device wake up and see immediate results.

Kind of a big deal

Re: Gigabit Stepping down to 100mbit, fixed by power cycle, cable switch

Is the device being used internally or externally?  Could be moisture or dust causing the issue or simply a bad cable. 

Meraki CMNO, Ruckus WISE, Sonicwall CSSA, Allied Telesis CASE & CAI
Head in the Cloud

Re: Gigabit Stepping down to 100mbit, fixed by power cycle, cable switch

Ive had this happen to connections in bedrooms, outdoors, and basements with non insulated doors to the elements.

Networking geek since high school where I got half of a CCNA. Played Marathon II and Infinity over localtalk.
Made many a network over the years, now de facto admin of a retreat center with some of this fine Meraki hardware.
Fortune 100 Tech veteran/refugee.
Kind of a big deal

Re: Gigabit Stepping down to 100mbit, fixed by power cycle, cable switch

Hmm, how old is the wiring and what type Cat5, Cat5e etc

Meraki CMNO, Ruckus WISE, Sonicwall CSSA, Allied Telesis CASE & CAI
Head in the Cloud

Re: Gigabit Stepping down to 100mbit, fixed by power cycle, cable switch

All newer installations. Cat5e and later. One of them had this really thin old Belkin cable and I was like ehhhhh no. I did not install this. There are ethernet cables you can just feel are crap. 

Networking geek since high school where I got half of a CCNA. Played Marathon II and Infinity over localtalk.
Made many a network over the years, now de facto admin of a retreat center with some of this fine Meraki hardware.
Fortune 100 Tech veteran/refugee.
Kind of a big deal
Kind of a big deal

Re: Gigabit Stepping down to 100mbit, fixed by power cycle, cable switch

Also be aware of CCA cables they are aluminium cores with a very thin layer of copper on top, never use them unless you don't care about connection integrity

Head in the Cloud

Re: Gigabit Stepping down to 100mbit, fixed by power cycle, cable switch

Jeez got it. I know the STP FTP and all that but this I hadn't heard of. Any easy way to know if you have one by looking at the jacket? 

Networking geek since high school where I got half of a CCNA. Played Marathon II and Infinity over localtalk.
Made many a network over the years, now de facto admin of a retreat center with some of this fine Meraki hardware.
Fortune 100 Tech veteran/refugee.
Kind of a big deal
Kind of a big deal

Re: Gigabit Stepping down to 100mbit, fixed by power cycle, cable switch

@RumorConsumer it might say CCA on the jacket like this:

Screenshot_20210112-213721_Chrome.jpg

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