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Re: [RRG] The use of UDP in LISP
On 10 dec 2007, at 17:51, Stephen Sprunk wrote:
In IPv4 UDP checksums are optional, but not in IPv6.
That's because IPv4 has its own header checksum and IPv6 doesn't.
If you say so...
The work for IPv6 with a UDP checksum is no worse than for IPv4
without a UDP checksum.
Huh? If there is no checksum you simply process the packet -> done. If
there is a checksum, you need to sum all 16-bit words in the packet,
which is a somewhat expensive operation if you can't do it while
you're copying the packet anyway.
I guess you could optimize this by taking the checksum from the TCP or
UDP payload of the inner packet and just do an incremental checksum of
everything that's not part of that checksum (only a few IP header
fields and the new UDP and other headers that are inserted). But not
doing a checksum is a much more attractive proposition.
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