Differences in reported interface speed? (RB750G, 5.6)

Output of " interface ethernet monitor $INTERFACE once" looks good, those two links are 1Gbps links:

[admin@mikrotik] > interface ethernet monitor nas once
status: link-ok
auto-negotiation: done
rate: 1Gbps
full-duplex: yes

[admin@mikrotik] > interface ethernet monitor lan once
status: link-ok
auto-negotiation: done
rate: 1Gbps
full-duplex: yes

Output (truncated to interfaces “nas” and “lan”) shows only 100Mbps?

[admin@mikrotik] > interface ethernet print detail
Flags: X - disabled, R - running, S - slave

1 R name=“lan” mtu=1500 l2mtu=1524 mac-address=[deleted]
arp=enabled auto-negotiation=yes full-duplex=yes > speed=100Mbps
master-port=none bandwidth=unlimited/unlimited switch=switch1

3 RS name=“nas” mtu=1500 l2mtu=1524 mac-address=[deleted]
arp=enabled auto-negotiation=yes full-duplex=yes > speed=100Mbps
master-port=lan bandwidth=unlimited/unlimited switch=switch1

So, 1Gbps is the correct speed, why does " interface ethernet print detail" show only 100Mbps?

That’s the setting on the port - it is hard set to 100/full. However, it is also set to auto negotiation, so it ignores the hard set parameters and the interface negotiates 1000/full with the other side. If you were to set auto-negotation=no, it would then drop to 100/full as per the hard parameters.

Or to put it differently: there is a section where the link is configured - the parameters of the interface, as displayed by “/interface ethernet print detail”. There are three parameters: speed, duplex, and auto-negotiation. If auto-negotiation is set to ‘no’ it is off, and the speed and duplex parameters are applied to the interface. If auto-negotiation is set to ‘yes’ it is on, and the speed and duplex parameters are ignored and the speed and duplex are negotiated with the peer on the other side of the link. “/interface ethernet monitor” shows you the actual settings of the interface at that moment, regardless of whether they were derived from auto-negotiation or the speed and duplex parameters.

On an unrelated side note: there is absolutely no reason to edit out MAC addresses. MAC addresses don’t leave broadcast domains. There’s nothing anyone can do with just knowing your MAC addresses. You could tattoo a list of MAC addresses on your forehead and be safe - if someone was in a position to abuse that list he’d also have to be directly connected to your network in order to use that information. Yet if the attacker is directly connected to your network it is trivial to generate just that list of MAC addresses.

Ah, that makes sense, didn’t think of it that way. Thank you!

Never leak any kind of information not necessary to solve a problem :slight_smile: Just a habit I’ve grown over the years. One could argue that I’d have to redact the interface-names as well, I know.. :wink: