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Packet Format Issues #227: Need Shim Header to indicate Crypto Property of packet Do we need to add pre-amble header to indicate if data is encrypted or not. Leads up to comments for #146 (in some 224/89 list comments) Comments: Need to determine if data is plain text or DTLS. WG List proposed text for new 32 bit pre-amble header, with 1 bit reserved for DTLS payload identification. No Consensus yet Do we put the pre-amble/mux on the capwap data channel. (from #146 comments on list) CON: Wastes 31 bits, since 1 bit is to used to tell if encrypted or not. CON: Since we set up a UDP tunnel in the first place it’s a property of that channel if the data is encrypted or not. FOR: the Lookup to check if the data is encrypted or not, is slower than just looking at 1 bit in header. FOR: an AC will have to handle non-encrypted traffic and MAY have to handle encrypted traffic (optional). So will have to do a table look up to check for data encryption for each packet. Less processing to know encrypted in packet. Alternate proposal, put bit in the capwap header and move the capwap header out of the data portion. Can’t capwap hdr comes after dtls header. WG decided to protect the entire capwap header. |