[CentOS] network interface up but no data

Dominik Zyla gavroche at gavroche.pl
Mon Oct 25 09:49:10 EDT 2010


On Fri, Oct 22, 2010 at 10:58:34AM +1100, Nat N wrote:
> On Thu, Oct 21, 2010 at 9:52 PM, Nat N <phenisha at gmail.com> wrote:
> > Hi List,
> >
> > I am running a x86_64 Centos server, after a reboot the network has decided to
> > not work.. this particular machine has 8 eth ports eth0-7. eth0 and eth3 were
> > bonded (mode 1 ) after reboot the bond did not work. It came up OK but no
> > data was passing through it. all other interfaces on the machine were working.
> >
> > I decided to remove the bond, so after removing the bond i was left with eth0
> > using the same IP as the bond used. however it still does the same thing,
> > it starts up with no errors but i cannot even ping the default gateway,
> > tcpdump shows nothing on the interface.
> >
> > I have made sure of the following
> > * no iptables installed
> > * kernel modules for the NIC are loaded with no errors
> > * the bond kernel module is not installed / all bond configs have been removed
> >
> > Below is some info on the interface, it should be noted that all others are OK
> > the only 2 that were having the issue are eth0 and eth3 (the ex-bonded ones)
> >
> > server1:/etc/sysconfig/network-scripts# ip route  | grep 172.18
> > 172.18.16.0/24 dev eth0  proto kernel  scope link  src 172.18.16.1
> > default via 172.18.16.254 dev eth0
> >
> >
> > # ifconfig eth0
> > eth0      Link encap:Ethernet  HWaddr 00:24:49:C8:66:98
> >          inet addr:172.18.16.1  Bcast:172.18.16.255  Mask:255.255.255.0
> >          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
> >          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> >          TX packets:7223 errors:0 dropped:0 overruns:0 carrier:0
> >          collisions:0 txqueuelen:1000
> >          RX bytes:0 (0.0 b)  TX bytes:463918 (453.0 KiB)
> >          Interrupt:226 Memory:dc000000-dc012800
> >
> >
> > If you look closely TX  and RX are massively different, but I am not
> > seeing anything on tcpdump even there is a large number of TX packets.
> >
> 
> Just some more information on this issue.
> 
> I have tried different kernels and the same issue is still occurring.
> 
> # ethtool eth0
>  Settings for eth0:
> 	Supported ports: [ TP ]
> 	Supported link modes:   10baseT/Half 10baseT/Full
> 	                        100baseT/Half 100baseT/Full
> 	                        1000baseT/Full
> 	Supports auto-negotiation: Yes
> 	Advertised link modes:  10baseT/Half 10baseT/Full
> 	                        100baseT/Half 100baseT/Full
> 	                        1000baseT/Full
> 	Advertised auto-negotiation: Yes
> 	Speed: 1000Mb/s
> 	Duplex: Full
> 	Port: Twisted Pair
> 	PHYAD: 1
> 	Transceiver: internal
> 	Auto-negotiation: on
> 	Supports Wake-on: g
> 	Wake-on: d
> 	Link detected: yes
> 
> #mii-tool -v eth0
> eth0: negotiated, link ok
>   product info: vendor 00:08:18, model 54 rev 6
>   basic mode:   autonegotiation enabled
>   basic status: autonegotiation complete, link ok
>   capabilities: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD
>   advertising:  100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control
> 
> 
> I am still racking my brains on what is causing this

Maybe you have problem with switch configuration instead of system one.

-- 
Dominik Zyla

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