Network Latency Issues

It is sometimes common that we see network network hiccups or connectivity issues in Alert log files. Usually it would be an System Admin who may determine whether there is something wrong on the NIC or Network Engineer if something is wrong over the network.

In case this happens when you are logged in to the Database and suddenly you find there is some network issue you can try below troubleshooting steps

1. Ping to the Loop back interface ( To check on NIC Card)

Messages sent to loopback IP addresses like 127.0.0.1 do not reach outside to the local area network (LAN) but instead are automatically re-routed by the computer's own network adapter back to the receiving end of the TCP/IP stack.

2. Ping to the default gateway ( To test connection between your computer and your router)

3. Trace route command (to the destination server IP)
This would determine the number of hops and the response of each path in the Network Path.

4. Check the domain Name resolution of the destination server using it hostname.
This tests your computer and network's ability to resolve network names (translating them to IP addresses).



Note:- In server which are placed in DMZ, Ping requests would be disabled.

We can Enable or Disable ping requests as below

On Windows Server
(How to enable  -> Start >> Administrative Tools >> Windows Firewall with Advanced Security >> Inbound Rules >> File and Printer Sharing (Echo Request – ICMPv4-IN) >> right click and select Enable Rule ) OR from command line (netsh firewall set icmpsetting 8)



On Linux Server

# iptables -A INPUT -p icmp -j DROP

OR

 # echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_all   // "0" - Disables ping request

OR

Append In
# vi /etc/sysctl.conf  

net.ipv4.icmp_echo_ignore_all =1 // 0 - Disables the ping request