The negotiated Ethernet links on the network interfaces should be
stable and the interface error counters should not increase. The
status and the counters can be seen with the command
show interfaces <interface name>
.
The counters in this output are cumulative since the start-up of
the appliance and they can be reset to zero with the command
clear interfaces
.
Figure 4.5. The output of "show interfaces primary"
SH # show interfaces primary Interface primary state Up: yes Interface type: ethernet IP address: 10.17.6.119 Netmask: 255.255.255.128 IPv6 address: 2001:44b8:7bf1:a50:d69a:20ff:fec2:520e/64 IPv6 auto-assigned: fe80::20e:b6ff:fe31:45e0/64 Speed: 100Mb/s (auto) Duplex: full (auto) MTU: 1500 HW address: 00:0E:B6:31:45:E0 RX bytes: 104060364 RX packets: 660069 RX mcast packets: 0 RX discards: 0 RX errors: 0 RX overruns: 0 RX frame: 0 TX bytes: 3658160 TX packets: 33089 TX discards: 0 TX errors: 1 TX overruns: 0 TX carrier: 1 TX collisions: 0
The following fields are important:
Up: Shows the administrative status of the network interface. Yes means that the interface is enabled.
Speed: The value is the speed used by the network interface. If the value contains the string (auto), then the speed is negotiated, otherwise it is a fixed speed.
Duplex: The value is the duplex setting used by the network interface. If the value contains the string (auto), then the duplex is negotiated, otherwise it is a fixed duplex setting.
MTU: The MTU size defined on this network interface.
RX bytes / RX packets / TX bytes / TX packets: The number of packets, sent and received, and the total number of bytes of data, sent and received.
RX discards / RX errors / RX frame: Number of Ethernet frames which could not be processed because the Ethernet frame was corrupted.
TX discards / TX errors / TX carrier / TX collisions: Number of Ethernet frames which could not be sent because of Ethernet layer related problems.
RX overruns / TX overruns: Number of Ethernet frames which could not be processed because the NIC ran out of memory to store incoming frames or wasn't fast enough with the processing of frames the buffer.
The Ethernet specification states that if no Ethernet link can be negotiated that the network interface speed should be set to 10 Mbps and the duplex should be set to half-duplex.
This situation can happen when one side of the Ethernet link is set to a fixed duplex/speed and the other side is set to auto-negotiation.
Figure 4.6. Interface set for auto-negotiation but coming up as half-duplex
SH # show interfaces lan0_0 Interface lan0_0 state Up: yes Interface type: ethernet Speed: 10Mb/s (auto) Duplex: half (auto) MTU: 1500 HW address: 00:0E:B6:8C:7A:EE Link: yes
Alternatively when the NIC on the Steelhead appliance is set to a fixed speed and duplex but it receiving a lot of RX/TX errors in the counters:
Figure 4.7. Interface set for fixed speed but with a lot of RX/TX errors
SH # show interfaces lan0_0 Interface lan0_0 state Up: yes Interface type: ethernet Speed: 100Mb/s Duplex: full MTU: 1500 HW address: 00:0E:B6:8C:7A:EE Link: yes RX bytes: 104060364 RX packets: 660069 RX mcast packets: 0 RX discards: 0 RX errors: 12737 RX overruns: 0 RX frame: 12737 TX bytes: 3658160 TX packets: 33089 TX discards: 0 TX errors: 19244 TX overruns: 0 TX carrier: 6921 TX collisions: 12323
These RX/TX counters are cumulative so make sure they are actually increasing before drawing conclusions about them.