Home / server / Questions / 124502
In Process
Hafthor
Asked: 2010-03-20 21:28:38 +0800 CST

Ping to IP address returned Destination Unreachable for a different IP address... huh?

  • 772

This was totally an isolated incident, but I performed this command:

ping 192.168.1.134

and got this result [image]:

Pinging 192.168.1.134 with 32 bytes of data:
Reply from 192.168.1.133: Destination host unreachable.
Reply from 192.168.1.134: bytes=32 time=75ms TTL=128
Reply from 192.168.1.134: bytes=32 time=83ms TTL=128
Reply from 192.168.1.134: bytes=32 time=96ms TTL=128

note the .133 in the first 'unreachable' reply. I guess I don't understand how this is possible - even given a totally crazy coincidence.

ip ping icmp

2 Answers

  1. ARP is used to resolve an IP address to Mac address. THe first IP address you see , actually is your machine or it could be your gateway. If it is your machine it means that the sender and receiver of the packet are on the same physical network, and since your machine could not resolve the sender's IP address to its MAC, your machine(.133) says "Destination host unreachable") If the sender and the receiver are on two different networks, then .133 could be the address of the gateway, where it says the same thing.

    Maybe an Arp timeout, if you don't have the machine mac address in your arp table, then your machine will send out a arp request. Looks like you network is quite busy as 96ms (is that your lan) means you lan is congested, or you or you remote host (or both) is under a great deal of load.

    LAN ping times should always be <1ms :-).

    Congestion leads to packet loss, packet loss leads degraded performance, degraded performance leads to the dark side. Check your network health and see whats going on.

    try running a netstat -s and see if your got lots of re-transmits. also ifconfig and see if your interfaces are error free! (that's a both ends)

    Check the network device your plugged into, does it have interface errors?

    What is your topology? why do you have such high ping times on a machine on the same subnet?

    After the first packet got sent, the IP address was correctly resolved to the MAC address and the ping went through.

    • 9

  2. Definitely, looks like an ARP issue, maybe an ARP timeout.

    • 0