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New Member

How "source ip" in icmp packet effect the results?

what importance source ip has in icmp packet

and how it effects the results

As i am having completly different results to same destination with different source ip

ping generated by same router towards same destination router over same link

ping 10.10.10.1 source 1.1.1.1 ---- latency 55ms

ping 10.10.10.1 source 2.2.2.1 ---- latency 6ms

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New Member

Re: How "source ip" in icmp packet effect the results?

Hi !

1.every Ip Packet has a source and a destination Ip address

ICMP echoreply the answer is sent back to the source address of the ICMP echo packet

So if your destination noide ( 10.10.10.1 ) has different paths in his routing table for reaching both addresses packets have diff. latency.

if you omit the source address the packet will get the interface address nearest to the destination as source address.

2. in order to send L3 packets the corresponding L2 mac-address need to be known, so for the first request and response packet before forwarding arp request has to be done. Therefore sometimes the first Ping packet times out.

3. ICMP is often rate-limited ( to the routers CPU) so ICMP is not a good way to measure latency.

    better way is to use udp ( e.g IP SLA)

4. ping sends typically more than one packet and depending on the OS either gives response time for each packet or average ( sometimes with min/max), so what are your values ?

with best regards

Alexander

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