Can you think of any legitimate reason to set gigabit switches to 100mbps?

ColdAsIce

ColdAsIce

ColdAsIce

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Joined
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This summer i've realised the local network where I work has been more sluggish than usual. After doing some testing I realised my max download speed over the LAN to one of the file servers was capping out at 11MB/s

Switches are decent Avaya gigabit switches and the whole back bone is fibre to the different switch cabinets and CAT6 from the cabinets to the network ports on the wall. Looks like some sort of policy being placed across the network to purposely throttle them to 100mbps instead of 1000mbps which the switches support.
 
Is it all the ports set to 100Mbps? Perhaps someone did a config change and got it wrong?

If it's just a single link, then dodgy port, cable or negotiation gone bad?
 
Unless there is some kind of network sniffing/logging system which might get overwhelmed (seems unlikely in this day and age) or a deliberate policy in some kind of misguided approach to trying to even out bandwidth use I can't think why.
 
OldKitMan said:
Is it all the ports set to 100Mbps? Perhaps someone did a config change and got it wrong?

If it's just a single link, then dodgy port, cable or negotiation gone bad?
Click to expand...

Would be impossible to check every single port as it would run into 500+ but I've tested across multiple VLANS and asked colleagues to check their sites an it's the same there. It's also having an effect on internet speed test. Connection should be 200mbps+ with scope to getting upgraded into the 350mbps region soon. I have speed tests saved from last year when I was hitting 200mbps but all testing last week I couldn't get past 90mbps. Seems like a ridiculous underutilization of the resources placing this cap but I just wanted to check for an obvious reason to do this.
 
Usually if it’s the odd port it’s because of auto neg. If it’s been done everywhere then the network team have done it for a reason, you’d have to ask them.
 
It wouldn’t surprise me that somewhere there is an aggregation switch that someone has accidentally pressed the 10/100/1000 button on once too often.

It’s always worth asking IT the question!
 
It's more than likely that you've negotiated down to that speed, or someone has bought the cheapest IP phones they can find without realising they only have 100Mbps ports on them.
 
Spoke to one of the old network guys that left a few months back. The uplink to the core is 1GB so all ports are set to 100mbps so that the uplink doesn't get saturated.
 
It's an interesting alternative to putting QoS in place or upgrading the links into the core, because 48x100 is still more than 1000.
 
I have have to set ports to 100Mbps in the distance past as some very old devices worked better when the port matched the device speed. No idea why anyone would push this out across the entire network and we are talking 15+ year old devices. More recently I came across some rooms which ended up at 100Mbps due to old network cabling degrading rather then the ports being set to 100Mbps. Though I see you have found your answer.

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