Networking :: ICMP Got Lower Priority?

Mar 16, 2010

I run a linux box as a gateway behind a satellite modem. The internet link over the satellite modem is only 1mbit so the usage often reaches 100% when someone is downloading/uploading something. I am seeing my ping return time jump from 700ms to 6000ms if someone tries to upload a file (by sending a attachment in a email etc). The satellite operator is saying this is normal, but I have my doubts.

Has ICMP got a lower priority? Should I really be seeing this behaviour? I understand that if it was a TCP packet then it would just be queued until the previous acknowledgement has been received. And if it was a UDP packet then it would have been dropped, but how does ICMP deal with these situations during heavy traffic?

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May 12, 2011

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Code:
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Dec 1, 2010

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iptables -t mangle -A PREROUTING -p icmp -j RETURN

with the help of port no or any other how can i identify the icmp packet ?... This below two is working fine

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Consider the below network

x.1|RTR1|-y.1---------y.2-|RTR2|-z.2------z.3-|LNX|-x.3
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[Code]....

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Code:
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[Code]...

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[code]...

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