Subject: IPV6_USE_MIN_MTU and IPV6_DONT_FRAG questions

From: Mark Andrews <[email-masked]>
Date: Wed, 07 Nov 2012 12:30:54 +1100

Should setting IPV6_USE_MIN_MTU to one (1) result in fragmented TCP packets?
Should setting IPV6_DONTFRAG to one (1) work on TCP sockets?

Both options were set on the socket with the resulting packet trace.

For reference the stack was: OS X 10.8.2 (12C60)

Mark

12:24:05.521331 IP6 2001:470:1f00:820:6233:4bff:fe01:7585 > 2001:470:1f00:820:218:f3ff:feba:9a37: frag (0|1232) 53 > 49203: Flags [.], ack 31, win 8209, options [nop,nop,TS val 986656829 ecr 3464680466], length 120012159*- 194/0/0 SOA, RRSIG, RRSIG, DNSKEY, DNSKEY, RRSIG, NSEC, RRSIG, MX bsdi.dv.isc.org. 0, RRSIG, NS bsdi1.dv.isc.org., NS drugs.dv.isc.org., RRSIG, RRSIG[|domain]
12:24:05.521582 IP6 2001:470:1f00:820:6233:4bff:fe01:7585 > 2001:470:1f00:820:218:f3ff:feba:9a37: frag (1232|228)
12:24:05.522636 IP6 2001:470:1f00:820:6233:4bff:fe01:7585 > 2001:470:1f00:820:218:f3ff:feba:9a37: frag (0|1232) 53 > 49203: Flags [.], ack 31, win 8209, options [nop,nop,TS val 986656829 ecr 3464680466], length 120020864 updateD [b2&3=0x50c3] [20596a] [50814q] [43695n] [14436au] Type35395 (Class 51553)? dv.isc.org.[|domain]
12:24:05.522887 IP6 2001:470:1f00:820:6233:4bff:fe01:7585 > 2001:470:1f00:820:218:f3ff:feba:9a37: frag (1232|228)

-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE:	+61 2 9871 4742		         INTERNET: [email-masked]