I'm not sure if this is a kernel thing or a NetworkManager thing. Did something change in how IPv6 router advertisements are handled by NetworkManager in Fedora 20?
On my Fedora 20 system, the Link MTU option recevied from IPv6 router advertisements is not being applied to the interface configuration: kernel-3.16.2-200.fc20.x86_64 NetworkManager-0.9.9.0-44.git20131003.fc20.x86_64 >cat /proc/sys/net/ipv6/conf/wlp2s0/mtu 1500 On my Fedora 19 system, this is working: kernel-3.14.18-100.fc19.x86_64 NetworkManager-0.9.8.8-2.fc19.x86_64 >cat /proc/sys/net/ipv6/conf/p4p1/mtu 1480 In both cases, the RA has the Link MTU option: >sudo rdisc6 -1 wlp2s0 Soliciting ff02::2 (ff02::2) on wlp2s0... Hop limit : 64 ( 0x40) Stateful address conf. : No Stateful other conf. : No Mobile home agent : No Router preference : medium Neighbor discovery proxy : No Router lifetime : 300 (0x0000012c) seconds Reachable time : unspecified (0x00000000) Retransmit time : unspecified (0x00000000) Prefix : 2001:xxxx:xxxx:1::1/64 On-link : Yes Autonomous address conf.: Yes Valid time : 300 (0x0000012c) seconds Pref. time : 300 (0x0000012c) seconds MTU : 1480 bytes (valid) Source link-layer address: 68:7F:74:xx:xx:xx from fe80::6a7f:74ff:fexx:xxxx I need this option because my IPv6 router uses a HE.net tunnel which adds 20 bytes of overhead for the 6in4 encapsulation, and many sites break PMTUD which causes those sites to hang. _______________________________________________ networkmanager-list mailing list networkmanager-list@gnome.org https://mail.gnome.org/mailman/listinfo/networkmanager-list