Date: Wed, 10 Nov 2010 21:26:56 -0800 From: "Kevin Oberman" <oberman@es.net> To: "Wilkinson, Alex" <alex.wilkinson@dsto.defence.gov.au> Cc: freebsd-stable@freebsd.org Subject: Re: icmp packets on em larger than 1472 [SEC=UNCLASSIFIED] Message-ID: <20101111052656.21C0E1CC0E@ptavv.es.net> In-Reply-To: Your message of "Thu, 11 Nov 2010 13:01:26 %2B0800." <20101111050126.GA41634@stlux503.dsto.defence.gov.au>
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> Date: Thu, 11 Nov 2010 13:01:26 +0800 > From: "Wilkinson, Alex" <alex.wilkinson@dsto.defence.gov.au> > Sender: owner-freebsd-stable@freebsd.org > > > 0n Wed, Nov 10, 2010 at 04:21:12AM -0800, Kirill Yelizarov wrote: > > >All my em cards running 8.1 stable don't reply to icmp echo requests packets larger than 1472 bytes. > > > >On stable 7.2 the same hardware works as expected: > ># ping -s 1500 192.168.64.99 > >PING 192.168.64.99 (192.168.64.99): 1500 data bytes > >1508 bytes from 192.168.64.99: icmp_seq=0 ttl=63 time=1.249 ms > >1508 bytes from 192.168.64.99: icmp_seq=1 ttl=63 time=1.158 ms > > > >Here is the dump on em interface > >15:06:31.452043 IP 192.168.66.65 > *****: ICMP echo request, id 28729, seq 5, length 1480 > >15:06:31.452047 IP 192.168.66.65 > ****: icmp > >15:06:31.452069 IP **** > 192.168.66.65: ICMP echo reply, id 28729, seq 5, length 1480 > >15:06:31.452071 IP *** > 192.168.66.65: icmp > > > >Same ping from same source (it's a 8.1 stable with fxp interface) to em card running 8.1 stable > >#pciconf -lv > >em0@pci0:3:4:0: class=0x020000 card=0x10798086 chip=0x10798086 rev=0x03 hdr=0x00 > > vendor = 'Intel Corporation' > > device = 'Dual Port Gigabit Ethernet Controller (82546EB)' > > class = network > > subclass = ethernet > > > ># ping -s 1472 192.168.64.200 > >PING 192.168.64.200 (192.168.64.200): 1472 data bytes > >1480 bytes from 192.168.64.200: icmp_seq=0 ttl=63 time=0.848 ms > >^C > > > ># ping -s 1473 192.168.64.200 > >PING 192.168.64.200 (192.168.64.200): 1473 data bytes > >^C > >--- 192.168.64.200 ping statistics --- > >4 packets transmitted, 0 packets received, 100.0% packet loss > > works fine for me: > > FreeBSD 8.1-STABLE #0 r213395 > > em0@pci0:0:25:0:class=0x020000 card=0x3035103c chip=0x10de8086 rev=0x02 hdr=0x00 > vendor = 'Intel Corporation' > device = 'Intel Gigabit network connection (82567LM-3 )' > class = network > subclass = ethernet > > #ping -s 1473 host > PING host(192.168.1.1): 1473 data bytes > 1481 bytes from 192.168.1.1: icmp_seq=0 ttl=253 time=31.506 ms > 1481 bytes from 192.168.1.1: icmp_seq=1 ttl=253 time=31.493 ms > 1481 bytes from 192.168.1.1: icmp_seq=2 ttl=253 time=31.550 ms > ^C The reason the '-s 1500' worked was that the packets were fragmented. If I add the '-D' option, '-s 1473' fails on v7 and v8. Are the V8 systems where you see if failing without the '-D' on the same network segment? If not, it is likely that an intervening device is refusing to fragment the packet. (Some routers deliberately don't fragment ICMP Echos Request packets.) -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman@es.net Phone: +1 510 486-8634 Key fingerprint:059B 2DDF 031C 9BA3 14A4 EADA 927D EBB3 987B 3751
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