[CentOS] network interface up but no data

Thu Oct 21 23:58:34 UTC 2010
Nat N <phenisha at gmail.com>

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
> dev eth0  proto kernel  scope link  src
> default via dev eth0
> # ifconfig eth0
> eth0      Link encap:Ethernet  HWaddr 00:24:49:C8:66:98
>          inet addr:  Bcast:  Mask:
>          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
	Supports auto-negotiation: Yes
	Advertised link modes:  10baseT/Half 10baseT/Full
	                        100baseT/Half 100baseT/Full
	Advertised auto-negotiation: Yes
	Speed: 1000Mb/s
	Duplex: Full
	Port: Twisted Pair
	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