Joe, I think this discussion is about fragmenting the outer IP packet. There is a 3rd choice: to fragment the inner datagram, and/or use ICMP "datagram is too big" messages to facilitate PMTU discovery of the tunnel. This certainly seems to have been the intent, when one reads about the IPv4 DF flag. (And IPv6 always requires DF).
-Dave -----Original Message----- From: sfc [mailto:[email protected]] On Behalf Of Joe Touch Sent: Tuesday, May 05, 2015 12:33 PM To: Xuxiaohu; Donald Eastlake; [email protected] Cc: [email protected]; [email protected]; [email protected] Subject: Re: [sfc] [trill] Fwd: Mail regarding draft-ietf-trill-over-ip On 5/4/2015 7:23 PM, Xuxiaohu wrote: > In a word, IP-in-UDP is just intended for those network environments > where fragmentation on the tunnel layer and strong checksums are not > desired. That's insufficient. They are only applicable where fragmentation and a strong checksum are not *needed*. Once you run IP in IP (IP in UDP in IP qualifies as this), you have only two choices: - support fragmentation - use in networks that are engineered so that fragmentation is never needed As to the strong checksum, similarly you have to either support one or deploy the result where that checksum isn't needed - either because you know that all apps will have strong enough checksums of their own or because you know enough about the kinds of errors that will occur that strong checksums aren't needed. But the key there is to define a use case where these properties are true AND to limit the document solution to uses in those case ONLY. > For those network environments where fragmentation on the > tunnel layer and stronger checksums are required, GUE should be > considered instead. Agreed. Joe _______________________________________________ sfc mailing list [email protected] https://www.ietf.org/mailman/listinfo/sfc _______________________________________________ Int-area mailing list [email protected] https://www.ietf.org/mailman/listinfo/int-area
