I'm trying to understand how and what should one infer and know how is the network performing, are there any issues or any other details from the network metric values of eth0 and lo.

I understand that eth0 is the Ethernet interface and this type of interface is usually a NIC connected to the network. lo is the loopback interface and is a special network interface that the system uses to communicate with itself.

My server is Linux and when I give the command ifconfig, I get the below output -

$ ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 9000
        inet xx.xx.xx.xx  netmask xxx.xx.xx.xx  broadcast xx.xx.xx.xx
        ether xx:xx:xx:xx:xx:xx  txqueuelen 1000  (Ethernet)
        RX packets 13349035706  bytes 1316668448685 (1.1 TiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 9657708772  bytes 1221804236810 (1.1 TiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 44556
        inet xxx.xx.xx.xx  netmask xx.xx.xx.xx
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 5222476924  bytes 1073912089796 (1000.1 GiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 5222476924  bytes 1073912089796 (1000.1 GiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

and when I give the sar command (sar -n DEV 1 1) to get the network devices vital statistics for eth0, eth1, etc, I see the below output -

10:14:00 AM     IFACE   rxpck/s   txpck/s    rxkB/s    txkB/s   rxcmp/s   txcmp/s  rxmcst/s
10:14:01 AM      eth0   5597.00   3895.00    485.25    469.72      0.00      0.00      0.00
10:14:01 AM        lo    892.00    892.00    181.34    181.34      0.00      0.00      0.00

Average:        IFACE   rxpck/s   txpck/s    rxkB/s    txkB/s   rxcmp/s   txcmp/s  rxmcst/s
Average:         eth0   5597.00   3895.00    485.25    469.72      0.00      0.00      0.00
Average:           lo    892.00    892.00    181.34    181.34      0.00      0.00      0.00

So, if I collect the above data over the period of time, what should I be understanding from the numbers and how should I understand what went wrong if any?

closed as too broad by Rui F Ribeiro, Ipor Sircer, G-Man, Stephen Harris, Jeff Schaller Dec 6 at 0:31

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