The upper layer checksum raises questions.. However this is used in the current implementation.
[ ] Can we adapt the text in the draft?
[ ] Respond to Harald Alvestrand and Mike Mc Bride
Harald Alvestrand
SCION keeps accommodating the “checksum across layers 3 and 4”. This was a bad idea in 1975, and keeps being a bad idea now. The idea should (in my opinion) be relegated to gateways and kept out of the core.
The payload of a packet can be anything (does not affect SCION operation), but the header contains an integer saying which content it is, with the defined values being “UDP”, “TCP”, and some numbers for internal use. The process for constructing an IP packet from the SCION packet (or vice versa) is not described, but presumably involves mangling checksums - -dataplane describes a “virtual header” for constructing the checksum of things that require it, which implies that a gateway to non-SCION IP would mangle checksums inside the UDP or TCP packet.
(There are references in -overview to docs des
Mike McBride' mmcbride7@gmail.com
I discussed potential scion checksum issues (like why have them) with Eliot and understand that they’ve been discussed with scion authors so won’t get into that.
The upper layer checksum raises questions.. However this is used in the current implementation.