eth0 works great, eth1 not working

Krishsrinath · 12-05-2011, 05:15 AM

Even I have faced this problem with linux systems having multiple nics.

Change the IP address to different Subnet and it will work.

Still want to know if we can make both Eth Ports of the same system to work in same subnet.

Thanks,
Krishsrinath

nesses · 10-01-2015, 07:07 AM

I had the same mindblowing problem, in my case the autonegotiation was not active (strange but ...):

read "en.wikipedia.org/wiki/Autonegotiation" for more information.

I tried

Code:

# ethtool eth0
Settings for eth0:
        Supported ports: [ TP MII ]
        Supported link modes:   10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
        Supported pause frame use: No
        Supports auto-negotiation: Yes
        Advertised link modes:  Not reported
        Advertised pause frame use: No
        Advertised auto-negotiation: No
        Speed: 100Mb/s
        Duplex: Full
        Port: MII
        PHYAD: 1
        Transceiver: internal
        Auto-negotiation: off
        Supports Wake-on: pumbg
        Wake-on: d
        Current message level: 0x00000000 (0)
                               
        Link detected: yes

then I checked mii-tool

Code:

# mii-tool eth0
eth0: 100 Mbit, full duplex, link ok

as we can see no negotiation.

you can activate the negotiation by simply run

Code:

# ethtool -s eth0 speed 100 duplex full autoneg on

then wait a few seconds because the card now recives the information from the link partner

after a second or two...

Code:

# ethtool eth0
Settings for eth0:
        Supported ports: [ TP MII ]
        Supported link modes:   10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
        Supported pause frame use: No
        Supports auto-negotiation: Yes
        Advertised link modes:  100baseT/Full 
        Advertised pause frame use: Symmetric
        Advertised auto-negotiation: Yes
        Link partner advertised link modes:  10baseT/Half 10baseT/Full 
                                             100baseT/Half 100baseT/Full 
        Link partner advertised pause frame use: Symmetric
        Link partner advertised auto-negotiation: Yes
        Speed: 100Mb/s
        Duplex: Full
        Port: MII
        PHYAD: 1
        Transceiver: internal
        Auto-negotiation: on
        Supports Wake-on: pumbg
        Wake-on: d
        Current message level: 0x00000000 (0)
                               
        Link detected: yes

and

Code:

# mii-tool eth0
eth0: negotiated 100baseTx-FD flow-control, link ok

now you should be able to talk with other hosts

Code:

# ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=52 time=28.3 ms
^C
--- 8.8.8.8 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 28.339/28.339/28.339/0.000 ms

Have a nice day!