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All zero IPs are said to be unknown IPs.

I'm wondering, if the source IP or the destination IP of a IP packet is all zero, how do IP routers deal with it?

FYI: I'm doing research, and I want to use all zero IPs for a user-defined case, but I'm afraid all zero IPs are already used for other purposes in standard specifications or current router implementations.

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Why are you asking? What problem are you trying to solve? – slhck Sep 5 '13 at 13:06
At what stages? What devices? Headers are empty (malformed)? – AthomSfere Sep 5 '13 at 13:11
A router probably can't do anything with a packet as all zeros as the destination. But you will see it on the local segment in DHCP requests. – Zoredache Sep 5 '13 at 15:36 is a nonstandard broadcast address used by some initial implementations of TCP/IPv4. RFC 1122 says that hosts should accept this destination address as "broadcast".

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but In reality, it is not used by Cisco router or Huawei routers, right? – misteryes Sep 5 '13 at 21:57
@misteryes: I don't know. I'm pretty sure it is not sent by such routers. But it is very possible that they accept this special address. Whether they do it or not, the conclusion is that this address already has special uses... – grawity Sep 7 '13 at 0:00

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