How to resolve packet loss & tranmission errors on a linux server. Please suggest.

[George Magklaras]

The fault could be either with your cable, hub/switch. Rarely it might 
be an autonegotiation issue between your host and the switch...
1)Check and if possibly replace your host's cable with a known good 
working one.
2)If the problem persists, try to change the port on the hub switch. If 
you connect to a managed switch, it could probably give you more useful 
stats.
3)Sometimes, autonegotiation (speed and duplex settings) between your 
server and a switch is to blame. Check that both your host's card and 
the switch are on the same duplex  and speed settings. If your switch 
supports the option of autonegotiation, turn it off and set the switch 
port explicitly to what your server ethernet card supports by default 
(eg, 100 Mbps FD , etc...).

If neither 1) 2) 3) solve the problem, something is happenning with your 
server interface. In that case, dmesg and cat /proc/net/dev might give 
us slightly more info than the netstat -i .

GM

unix syzadmin wrote:
> Hi,
> 
> In one of our Linux servers (RHEL-AS2.1 Update 5), the ping response was
> very slow.  From the following, it looks like there is a packet loss&
> transmission errors (80% packet loss, TX-ERR=39962)  .  Please suggest how
> to resolve this issue.
> 
> [root at bangpcrh212 root]# ping bangapps
> PING bangapps.bea.com (172.22.40.9) from 172.22.43.22 : 56(84) bytes of
> data.
> 64 bytes from bangapps.bea.com (172.22.40.9): icmp_seq=0 ttl=62 time=170
> usec
> 64 bytes from bangapps.bea.com (172.22.40.9): icmp_seq=1 ttl=62 time=298
> usec
> 64 bytes from bangapps.bea.com (172.22.40.9): icmp_seq=2 ttl=62 time=213
> usec
> 64 bytes from bangapps.bea.com (172.22.40.9): icmp_seq=3 ttl=62 time=254
> usec
> 
> --- bangapps.bea.com ping statistics ---
> 25 packets transmitted, 5 packets received, 80% packet loss
> round-trip min/avg/max/mdev = 0.168/0.220/0.298/0.052 ms
> [root at bangpcrh212 root]# netstat -i
> Kernel Interface table
> Iface       MTU Met    RX-OK RX-ERR RX-DRP RX-OVR    TX-OK TX-ERR TX-DRP
> TX-OVR Flg
> eth0       1500   0  3595100   0             0                  0  2813499
> 39962      0      0 BMRU
> eth0:1     1500   0        0      0              0                  0
> 0      0             0      0 BMRU
> eth0:2     1500   0        0      0              0                  0
> 0      0             0      0 BMRU
> eth0:3     1500   0        0      0              0                  0
> 0      0             0      0 BMRU
> eth0:4     1500   0        0      0             0                   0
> 0      0             0      0 BMRU
> lo        16436   0   252789   0              0                   0
> 252789   0            0      0 LRU
> 
> Thanks & Regards
> 
> -GnanaShekar-

-- 
--
George B. Magklaras

Senior Computer Systems Engineer/UNIX Systems Administrator
The Biotechnology Centre of Oslo,
University of Oslo
http://www.biotek.uio.no/

EMBnet Norway: http://www.biotek.uio.no/EMBNET/