When I run lshw -C network I get

       description: Ethernet interface
       product: Ethernet Connection (6) I219-V
       vendor: Intel Corporation
       physical id: 1f.6
       bus info: pci@0000:00:1f.6
       logical name: eno1
       version: 30
       serial: 1c:69:7a:0d:82:69
   --> size: 100Mbit/s         
   --> capacity: 1Gbit/s       
       width: 32 bits
       clock: 33MHz
       capabilities: pm msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=3.2.6-k duplex=full firmware=0.4-4 ip= latency=0 link=yes multicast=yes port=twisted pair speed=100Mbit/s
       resources: irq:133 memory:c0b00000-c0b1ffff

What's the difference between size and capacity in this case?


capacity is the maximum speed of the NIC (in this case, 1Gbit/s).
size is the current connection speed (in this case, 100Mbit/s).

Source: https://ezix.org/src/pkg/lshw/src/branch/master/src/core/network.cc

  • Meaning... you have a 1Gbit/s NIC but it's connected to something that limits it to only 100Mbit/s. – SnakeDoc Jun 18 '20 at 18:22
  • To expand on what @SnakeDoc wrote - it's also possible the are faults in the Ethernet cable / cable is too long, causing the card to pick a slower transfer rate. – Shaamaan Jun 19 '20 at 7:51

Those field names were intended for other types of hardware, and mapping them to network interfaces doesn't make that much sense. That said, in this context, "capacity" is the maximum bandwidth of the NIC, while "size" is the current bandwidth.

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