Re: Checksum in IPv6 header

[Rahim Choudhary <rahimchoudhary at yahoo.com>]

Thanks. I also heard from Brian McGehee. It is basically the same reason: efficiency by removing processing that is deemed unneeded. In this case the layer 2 and 4 checksums are relied upon and simplification and thereby performance is achieved at layer 3.

 

These are obvious reasons and I have seen them documented. Wonder on two things:

 

1. one if there were other reasons for not including checksum in IPv6 header, historically speaking if there was a contrary view?

 

2. second, concerns the security implication if any. Yes the checksum was intended for guarding against transmission errors, not as a security technique. The question is if there are some unintended security impact possible? Eventually the presence or absence of a checksum at layer 3 may be not too important because the checksum can be recomputed if some malicious change is inserted.

 

Thanks for the input.

 

Fred Baker <fred at cisco.com> wrote:

On Jan 28, 2008, at 2:03 PM, Rahim Choudhary wrote:

This may be a matter that is common knowledge to this list. But please forgive me for asking. What were the reasons that the IPv6 working group decided not to include a checksum field for the IPv6 packet Header? Does it have no security impact to omit the checksum?

The short version is that in general the checksum found implementation errors, but given a working system rarely found true operational errors. It's not stupid as a debug technique, but it doesn't result in packet discard in real networks, and so was deemed unjustified.

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