In message <2cf4cb03e2aa464ba0982ec92a02ce2509f86...@by2prd0512mb653.namprd05.prod.outlook.com>, Ronald Bonica wri tes: > > > > -----Original Message----- > > From: Brian E Carpenter [mailto:[email protected]] > > Sent: Friday, June 21, 2013 4:53 PM > > To: Ronald Bonica > > Cc: Ray Hunter; [email protected] 6man-wg > > Subject: Re: FW: New Version Notification for draft-bonica-6man-frag- > > deprecate-00.txt > > > > On 22/06/2013 07:53, Ronald Bonica wrote: > > >> I don't 100% agree. In the case that PMTUD is broken, there'd be > > >> nothing to stop a current DNSSEC implementation from always assuming > > >> a default path MTU of 1280, without awaiting confirmation from > > PMTUD, > > >> and fragmenting the UDP packet pre-emptively [assuming fragmentation > > >> was not equally broken along the path as ICMP PTB was]. > > >> > > > > > > Do any implementations actually do this? > > > > > > If they do, how well are they working, today? > > > > Does it matter? > > Hi Brian, > > I think that it does. If a DNSSEC implantation fragments every packet larger > than 1280 bytes, regardless of whet > her that packet needs to be fragmented: > > - it ignores the advice of RFC 2460 and RFC 5405 > - it doesn't work very well today, because so many operators filter its > fragmented output > > AFAIKS, there are two ways to make this application work better: > > - make people stop filtering IPv6 fragments > - change the implementation's behavior > > Given that the former is impossible, it seems that the later is required. > > Ron
Named has set IPv6_USE_MIN_MTU for years for UDP. There are plenty of paths that have path mtu issues but not fragmentation issues (tunnels). Many firewalls allow fragments out but not icmp back in. Named currently sets IPv6_USE_MIN_MTU for TCP. Mark > -------------------------------------------------------------------- > IETF IPv6 working group mailing list > [email protected] > Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 > -------------------------------------------------------------------- -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: [email protected] -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
