Werid Network Interface Issue

Today i had a strange issue while working. One of the webseal server was not able to connect to LB(load balancer).

Simple telnet was failing. Since this host was rebooted recently . tried many other things but in vain.Thought issue could be either a load balancer or routing table on webseal.

telnet 10.39.X.X 80
Trying 10.39.X.X...
telnet: connect to address 10.39.X.X: No route to host

On further checking Systems team confirmed routing table is fine and network team LB is fine. But still telnet was failing :)

I was looking for system messages but hard luck.suddenly while at work for the same issue i noticed something strange,the network interface of the ip,was the problem .It looked weird to me. It was showing TX byte as zero.


ifconfig eth0
eth0 Link encap:Ethernet HWaddr x:x:x:x:x:x
inet addr:10.39.X.X Bcast:10.39.X.X Mask:255.255.255.0
inet6 addr: x::x:x:x:c6aa/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:157 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:6610 (6.4 KiB) TX bytes:0 (0.0 b)

TCPDump are pain for an Appadmin to run. So i simply restarted the interface and issue got resolved :)

ifconfig -a

Display info on all network interfaces on server, active or inactive.

ifconfig eth0 down

If eth0 exists would take it down causing it cannot send or receive any information.

ifconfig eth0 up

If eth0 exists and in the down state would return it back to the up state allowing to to send and receive information.

And i could see by TX bytes:65316 (63.7 KiB) having some data :)

so the telnet started working fine and client's site up, and running again.