2500BaseT with Intel X550 and CRS310

RouterOS
1

Hi,

after replacing my old unmanaged Buffalo Multi-Gig Switch with a Mikrotik CRS310-8G+2S I have an issue getting a 2500BaseT connection to an Intel X550 working.

I updated RouterOS to 7.21.3 and also updated the RouterBoard firmware afterwards (via system/routerboard including rebooting).

The firmware on the Intel X550 is also updated to the latest 3.70. The Intel X550 is running in a Linux (Debian 13) system.

By default, the X550 advertises only 100/1000/10000 BaseT connections via autoneg, but lists also 2500 and 5000 BaseT as supported (via ethtool).

So by default autonegotiation results in a 1000BaseT link, which works.

As soon as I enable advertising of 2500 on the X550 (via ethtool -s eth0 advertise 0x1800000001028) the system is unable to establish a usable connection.

dmesg shows NIC link is up 2.5Gbps and about 4-5 seconds later NIC link is down. This repeats indefinetly.

If I force 2500BaseT on the X550, I get the same messages and issue.

If I disable autoneg on the CRS310 and set the speed manually to 2500BaseT, I get a stable connection, but WinBox (4.0.1) shows a red “unsupported speed” warning for the interface. Still, the link is up and running - without any transmission errors.

With the same X550 card and over the same cabling I was able to do up to 10GBaseT with the Buffalo switch I retired. 2500BaseT and 5000BaseT also worked with this setup.

I found some old information about similar issues with RouterOS 7.17 which were supposedly fixed in 7.18.

What I would like to achieve is working autonegotiation between the X550 and the CRS310 to be able to use both 1000BaseT and 2500BaseT connections. Since the X550 does not advertise 2500BaseT without (non-persistent) configuration, I would expect to be able to switch from 1000BaseT to 2500BaseT “on the fly” by adding the 2500BaseT advertisement on the X550 side and the CRS310 switching the link speed.

Again, this worked without any issues for years with that unmanaged Buffalo switch and only after swapping in the Mikrotik CRS310 I have the mentioned issues.

Since I don’t have too much experience with Mikrotik switches yet, did I miss a possibly relevant setting for this?

Does anybody else here have the same or a similar setup?

Or did I perhaps encounter a bug on the CRS310 side?

Any help would be greatly appreciated.

Thanks in advance, Peter

2

I ran into the exact same issue today with a CRS310-8G+2S+ (RouterOS 7.21.2) and an X550 updated to the latest Dell firmware.

Same workaround: advertising only 2.5G from the X550 and disabling autonegotiation on the Mikrotik side gives a stable link, but the "unsupported speed" warning persists.

Hoping this gets a proper fix from Mikrotik soon.

3

Same issue here, also with a CRS310-8G+2S+, but in my case the client devices are Macbook Pro laptops with 2.5G realtek 8156 series USB nics.

If auto-negotiation is enabled, the link stays down, but with the above settings (autoneg off, 2.5G forced) it works perfectly other than the misleading error message.

If the message just said ‘ auto-negotiation disabled ‘ it might actually be useful.