Re: rge(4) RTL8125 2.5GbE testing: 2500baseT media type not available on 16.0-CURRENT

On Mon, Feb 23, 2026 at 4:37 AM Adrian Chadd <[email protected]> wrote:

> hi!
>
> ifconfig -m rge0 shows
>
>         supported media:
>                 media autoselect
>                 media 2500Base-T mediaopt full-duplex
>                 media 2500Base-T
>                 media 1000baseT mediaopt full-duplex
>                 media 1000baseT
>                 media 100baseTX mediaopt full-duplex
>                 media 100baseTX
>                 media 10baseT/UTP mediaopt full-duplex
>                 media 10baseT/UTP
>
> For some reason it's 2500base-T, not 2500baseT.
>
> # ifconfig rge0 media 2500baset mediaopt full-duplex
>
> Also works.
>
> I haven't plugged it into a 2.5G port though, I'll have to go do that
> and see what both ends try w/ forced and auto negotiation.
>
>
>
It shows a negotiated speed of 2.5G:

olivier@fbsd:~ $ ifconfig rge0
rge0: flags=1008843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,LOWER_UP> metric
0 mtu 1500
        options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
        ether 84:47:09:1d:07:bf
        inet 192.168.100.161 netmask 0xffffff00 broadcast 192.168.100.255
        media: Ethernet autoselect (2500Base-T <full-duplex>)

olivier@fbsd:~ $ sudo pciconf -lv rge0
rge0@pci0:2:0:0:        class=0x020000 rev=0x05 hdr=0x00 vendor=0x10ec
device=0x8125 subvendor=0x10ec subdevice=0x0123
    vendor     = 'Realtek Semiconductor Co., Ltd.'
    device     = 'RTL8125 2.5GbE Controller'
    class      = network
    subclass   = ethernet

However, I am experiencing the same 100Mb/s (yes 100) limitation that
occurred on both Ubuntu (with both the default r8169 and official Realtek
r8125 driver) and Windows:
Despite the reported link speed, the actual throughput is capped 100Mb/s:

olivier@fbsd:~$ iperf3 -c 192.168.100.1
(...)
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.06  sec   113 MBytes  94.3 Mbits/sec    0            sender
[  5]   0.00-10.08  sec   113 MBytes  94.1 Mbits/sec
 receiver

Regards,
Olivier