[PLUG] Baffled: CentOS 7 DHCP 10G fast, fixed 1G

Michael Dexter dexter at pdxlinux.org
Thu Nov 14 11:51:52 UTC 2019


On 11/13/19 1:07 PM, alan at clueserver.org wrote:
> What does ethtool tell you?

"DHCP" via network-scripts:

  Settings for p2p1:
Supported ports: [ TP ]
Supported link modes:   100baseT/Full
                         1000baseT/Full
                         10000baseT/Full
Supported pause frame use: Symmetric
Supports auto-negotiation: Yes
Advertised link modes:  100baseT/Full
                         1000baseT/Full
                         10000baseT/Full
Advertised pause frame use: Symmetric
Advertised auto-negotiation: Yes
Speed: 10000Mb/s
Duplex: Full
Port: Twisted Pair
PHYAD: 0
Transceiver: external
Auto-negotiation: on
MDI-X: Unknown
Supports Wake-on: d
Wake-on: d
Current message level: 0x00000007 (7)
       drv probe link
Link detected: yes

iperf3 sample:

[  4]   0.00-1.00   sec   114 MBytes   955 Mbits/sec    0    375 KBytes 

[  4]   1.00-2.00   sec   113 MBytes   946 Mbits/sec    0    375 KBytes 



$ sudo dhclient p2p1
[cecheverri at rbx-1 ~]$ sudo ethtool p2p1
Settings for p2p1:
Supported ports: [ TP ]
Supported link modes:   100baseT/Full
                         1000baseT/Full
                         10000baseT/Full
Supported pause frame use: Symmetric
Supports auto-negotiation: Yes
Advertised link modes:  100baseT/Full
                         1000baseT/Full
                         10000baseT/Full
Advertised pause frame use: Symmetric
Advertised auto-negotiation: Yes
Speed: 10000Mb/s
Duplex: Full
Port: Twisted Pair
PHYAD: 0
Transceiver: external
Auto-negotiation: on
MDI-X: Unknown
Supports Wake-on: d
Wake-on: d
Current message level: 0x00000007 (7)
       drv probe link
Link detected: yes

iperf3 sample:
[  4]   0.00-1.00   sec  1.10 GBytes  9.41 Gbits/sec    0   1.23 MBytes 

[  4]   1.00-2.00   sec  1.10 GBytes  9.42 Gbits/sec    3   1.14 MBytes 

[  4]   2.00-3.00   sec  1.09 GBytes  9.40 Gbits/sec    3   1.14 MBytes 


So, identical ethtool output unless I'm missing something?

Maybe responsible: There are two NICs on the same subnet as not to get 
locked out. Some OSs tolerate this while some do not. Because "dhclient" 
addressing works fine, I trust that is okay but the plan is to next try 
it without the 1GbE interface connected.

Other ideas?

In short, 'dhclient <interface>' gives a solid 10GbE. DHCP via 
network-scripts drops to 1GbE.

Michael



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