Hi Dino, > -----Original Message----- > From: Dino Farinacci [mailto:[email protected]] > Sent: Tuesday, February 12, 2013 9:05 AM > To: Templin, Fred L > Cc: [email protected] > Subject: Re: [lisp] RFC6830 comment > > > Hi, > > > > In RFC6830, Section 5.4.1, it says: > > > > "the ITR will drop the packet > > when the size is greater than L and send an ICMP Too Big message to > > the source with a value of S, where S is (L - H)." > > > > Shouldn't it be: "when the size is greater than (L - H)" ? > > L is the size of the packet that will leave the ITR so it won't be > fragmented by the ITR or any intermediate routers. S is the size of the > packet that must be received by the ITR to avoid fragmentation. > > L-H is S. So if S + H (calculated by the ITR is L) is greater than the > effective MTU, that is when the packet is dropped. That is what the text > says. > > You can explain this in terms of S, of (L-H), or in terms of L. We chose > to describe it by how the packet leaves the ITR, in terms of L.
OK, I went back and looked again and it looks clear enough. However, what should the ITR do if it gets an ICMP packet too big (PTB) message after sending an encapsulated packet to the ETR. Drop it? Cache the MTU size? Send a translated PTB message back to the original source? Section 5.4.1 of the document doesn't currently say. Thanks - Fred [email protected] > Dino > _______________________________________________ lisp mailing list [email protected] https://www.ietf.org/mailman/listinfo/lisp
