As I remember it IPv4 has a minimum packet size of 576 that won't (or at least shouldn't be) fragmented by IP.
Mike. Mike Sullenberger, DSE m...@cisco.com .:|:.:|:. Customer Advocacy CISCO > -----Original Message----- > From: ipsec-boun...@ietf.org [mailto:ipsec-boun...@ietf.org] On Behalf > Of Valery Smyslov > Sent: Wednesday, October 09, 2013 10:34 PM > To: Paul Wouters > Cc: ipsec@ietf.org > Subject: Re: [IPsec] I-D Action: draft-ietf-ipsecme-ikev2-fragmentation- > 03.txt > > >> I also think that PMTU discovery isn't very useful for IKE. > >> That's why it is MAY. > > > > That does not help implementors who still have to implement the MAY's. > > if even you as a document author does not think it is very useful, > > then I think it should just not be in the document. > > Sorry, I wasn't very clear. By "isn't very useful" I meant that it is not > useful > for the usual PMTU discovery goal in TCP - to find _maximum_ IP datagram > size that is not fragmented by IP level. In IKE its the goal is different - > to find > _some_reasonable_ IP datagram size that is not fragmented by IP. > > If we have the size that is guaranteed to not be fragmented, no PMTU > discovery will be needed. As far as I understand, for IPv6 it is 1280 bytes. > But > as far as I know, there's no such value for IPv4. > If we mandate (or recommend) using really small value e.g. 128 bytes, than > the performance will suffer badly, so it is not a good option. > I'm especially worrying about network I'm not familiar with - mobile > networks or other constrained environments. > It would be great if some experts in such networks could clarify this. > > _______________________________________________ > IPsec mailing list > IPsec@ietf.org > https://www.ietf.org/mailman/listinfo/ipsec _______________________________________________ IPsec mailing list IPsec@ietf.org https://www.ietf.org/mailman/listinfo/ipsec
