? how cisco router handle the out-of-order ICMP echo-reply packets
steve at ibctech.ca
Tue Jan 6 07:52:02 CST 2009
Scott Morris wrote:
> There aren't sequence numbers with ICMP. And the timeout value is
> watched/triggered before the next ICMP is sent, so there shouldn't really be
> any ordering problem/interpretation anyway.
FYI, from RFC 792:
The data received in the echo message must be returned in the echo
The identifier and sequence number may be used by the echo sender
to aid in matching the replies with the echo requests. For
example, the identifier might be used like a port in TCP or UDP to
identify a session, and the sequence number might be incremented
on each echo request sent. The echoer returns these same values
in the echo reply.
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