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Duke Dougal
Asked: 2019-05-28 21:08:10 +0800 CST

How can I diagnose this networking problem in which scp freezes temporarily?

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UPDATE: switching to use the network virtio driver seems to have fixed it.

I am trying to copy a file via scp from a virtual machine to a remote host.

After much effort I have found if I use an Ubuntu cloud image, the scp command sits in this state for about a minute or so:

ubuntu@ubuntu:~$ scp -i foo.pem logo-60263262.mp4 [email protected]:.
logo-60263262.mp4                               0%    0     0.0KB/s   --:-- ETA

before suddenly finishing the transfer:

ubuntu@ubuntu:~$ scp -i foo.pem logo-60263262.mp4 [email protected]:.
logo-60263262.mp4                             100%  645KB   6.9KB/s   01:33

Notice the above transfer took 1 minute 33 seconds.

Whereas on a Centos cloud image, the transfer happens in 2 seconds:

[centos@localhost ~]$ scp -i foo.pem logo-60263262.mp4 [email protected]:.
logo-60263262.mp4                                                                                                                                                                  100%  645KB 322.3KB/s   00:02

I'm out of ideas for diagnosing what is different between these two systems that is causing the problem on Ubuntu.

Can anyone suggest what I can do? It's the very latest versions of Centos 7 and Ubuntu 19 and I also tried Ubuntu 18

Ubuntu ifconfig:

ubuntu@ubuntu:~$ ifconfig
ens2: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.115  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::5054:ff:fee7:974d  prefixlen 64  scopeid 0x20<link>
        ether 52:54:00:e7:97:4d  txqueuelen 1000  (Ethernet)
        RX packets 3988  bytes 1623170 (1.6 MB)
        RX errors 0  dropped 3  overruns 0  frame 0
        TX packets 2435  bytes 3468401 (3.4 MB)
        TX errors 0  dropped 1 overruns 0  carrier 0  collisions 11541

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 204  bytes 16944 (16.9 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 204  bytes 16944 (16.9 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

ubuntu@ubuntu:~$

Centos ifconfig:

[centos@localhost ~]$ ifconfig
ens2: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.114  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::5054:ff:fe69:6aa1  prefixlen 64  scopeid 0x20<link>
        ether 52:54:00:69:6a:a1  txqueuelen 1000  (Ethernet)
        RX packets 3324  bytes 933660 (911.7 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2465  bytes 2877907 (2.7 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 6  bytes 416 (416.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 6  bytes 416 (416.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[centos@localhost ~]$
networking

1 Answers

  1. Look at ifconfig output, there are collisions detected on Ubuntu VM.

    TX errors 0  dropped 1 overruns 0  carrier 0  collisions 11541

    Duplicate IP?

    • 0