as most dns technologists are aware, ip and tcp have options, and udp does not. there is a draft:
https://datatracker.ietf.org/doc/draft-ietf-tsvwg-udp-options/ which has been ongoing since 2015, which proposes to add options to udp: Internet-Draft Transport Options for UDP September 2019 IP transport payload <-------------------------------------------------> +--------+---------+----------------------+------------------+ | IP Hdr | UDP Hdr | UDP user data | surplus area | +--------+---------+----------------------+------------------+ <------------------------------> UDP Length Figure 3 IP transport payload vs. UDP Length this relies on the unaccounted octets which follow the udp header and data, inside the ip length but outside the udp length. this is moderately controversial since it's a deliberate layering violation, but it may be more workable than creating a new "udp2" ip datagram type, due to middleboxes. the options proposed are: Internet-Draft Transport Options for UDP September 2019 Kind Length Meaning ---------------------------------------------- 0* - End of Options List (EOL) 1* - No operation (NOP) 2* 3 Option checksum (OCS) 3* 6 Alternate checksum (ACS) 4* 4 Lite (LITE) 5* 4 Maximum segment size (MSS) 6* 8/10 Fragmentation (FRAG) 7 10 Timestamps (TIME) 8 (varies) Authentication and Encryption (AE) 9 6 Request (REQ) 10 6 Response (RES) 11-126 (varies) UNASSIGNED (assignable by IANA) 127-253 RESERVED 254 N(>=4) RFC 3692-style experiments (EXP) 255 Reserved since dns has been the greatest single user of wide area udp, i suggest that those in dnsop who have an interest in this topic, please review this draft. something of this form will likely be created, in order to support quic, a new udp based transport protocol which is expected to be used by http/3. -- Paul _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
