On 11/03/14 09:20, Wolfgang S. Rupprecht wrote: > Ed Greshko <ed.greshko@xxxxxxxxxxx> writes: >> [egreshko@meimei ~]$ ping -s 1200 wifi (my gw) >> PING wifi.greshko.com (192.168.1.1) 1200(1228) bytes of data. >> 1208 bytes from wifi.greshko.com (192.168.1.1): icmp_seq=1 ttl=64 time=0.487 ms >> 1208 bytes from wifi.greshko.com (192.168.1.1): icmp_seq=2 ttl=64 time=0.501 ms >> So, no trouble here. Fully updated F20 system. > Hmm. I didn't really believe it could be an across the board problem > without anyone else noticing, but that leaves me with the question as to > what is going on here. I've got a similar claimed mtu of 1500. > > [wolfgang@arbol ~]$ ip link show p34p1 > 3: p34p1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000 > link/ether 08:60:6e:74:6f:e2 brd ff:ff:ff:ff:ff:ff > > Using a bit of binary search it turns out my largest working ping is 512 > bytes. That is a very suspicious number because it is power of two and > the actual packet still has a handful of bytes slapped onto the front > making it a non power of two. > > [wolfgang@arbol ~]$ ping -s 512 gw > PING gw.wsrcc.com (192.168.35.1) 512(540) bytes of data. > 520 bytes from gw.wsrcc.com (192.168.35.1): icmp_seq=1 ttl=64 time=0.538 ms > 520 bytes from gw.wsrcc.com (192.168.35.1): icmp_seq=2 ttl=64 time=0.521 ms > 520 bytes from gw.wsrcc.com (192.168.35.1): icmp_seq=3 ttl=64 time=0.453 ms > ^C > --- gw.wsrcc.com ping statistics --- > 3 packets transmitted, 3 received, 0% packet loss, time 2001ms > rtt min/avg/max/mdev = 0.453/0.504/0.538/0.036 ms > [wolfgang@arbol ~]$ ping -s 513 gw > PING gw.wsrcc.com (192.168.35.1) 513(541) bytes of data. > ^C > --- gw.wsrcc.com ping statistics --- > 9 packets transmitted, 0 received, 100% packet loss, time 7999ms > > [wolfgang@arbol ~]$ > > I've turned off all the hardware accelerators that ethtool knows about. > No change. > > [wolfgang@arbol ~]$ ethtool -k p34p1 > Features for p34p1: > rx-checksumming: off > tx-checksumming: off > tx-checksum-ipv4: off > tx-checksum-ip-generic: off [fixed] > tx-checksum-ipv6: off [fixed] > tx-checksum-fcoe-crc: off [fixed] > tx-checksum-sctp: off [fixed] > scatter-gather: off > tx-scatter-gather: off > tx-scatter-gather-fraglist: off [fixed] > tcp-segmentation-offload: off > tx-tcp-segmentation: off > tx-tcp-ecn-segmentation: off [fixed] > tx-tcp6-segmentation: off [fixed] > udp-fragmentation-offload: off [fixed] > generic-segmentation-offload: off > generic-receive-offload: off > large-receive-offload: off [fixed] > rx-vlan-offload: off > tx-vlan-offload: off > ntuple-filters: off [fixed] > receive-hashing: off [fixed] > highdma: off [fixed] > rx-vlan-filter: off [fixed] > vlan-challenged: off [fixed] > tx-lockless: off [fixed] > netns-local: off [fixed] > tx-gso-robust: off [fixed] > tx-fcoe-segmentation: off [fixed] > tx-gre-segmentation: off [fixed] > tx-ipip-segmentation: off [fixed] > tx-sit-segmentation: off [fixed] > tx-udp_tnl-segmentation: off [fixed] > tx-mpls-segmentation: off [fixed] > fcoe-mtu: off [fixed] > tx-nocache-copy: off > loopback: off [fixed] > rx-fcs: off > rx-all: off > tx-vlan-stag-hw-insert: off [fixed] > rx-vlan-stag-hw-parse: off [fixed] > rx-vlan-stag-filter: off [fixed] > l2-fwd-offload: off [fixed] > busy-poll: off [fixed] > [wolfgang@arbol ~]$ > > What is left? Some weirdness caused by my router announcing a low MTU > but Fedora not reporting it? I'm grasping at straws here. I've not made any adjustments to my tcp/ip stack. My ethtool output is slightly different than yours but that may be a red herring. What I would do is use "wireshark" with a capture filter of "icmp" and see what is going out on the wire. What I would do is "ping -c 1 -s 2000 gw" and then check to see that 2 packets are being sent out with the first one being marked as a fragment. -- If you can't laugh at yourself, others will gladly oblige. -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
