Date: Thu, 20 Nov 2003 16:05:06 +0200 From: Alexander Motin <mav@alkar.net> To: freebsd-ipfw@freebsd.org Subject: dummynet & IP fragmentation bug Message-ID: <3FBCCA12.1000906@alkar.net>
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Hello.
I have one strange problem with dummynet & IP fragmentation.
I have FreeBSD 4.8-RELEASE router with few interfaces:
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=3<rxcsum,txcsum>
inet 195.248.191.172 netmask 0xffffffc0 broadcast 195.248.191.191
ether 00:30:48:20:8e:7e
media: Ethernet autoselect (1000baseTX <full-duplex>)
status: active
ng4: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> mtu 1492
inet 195.248.191.172 --> 212.86.231.58 netmask 0xffffffff
Interface ng4 have MTU 1492 because it is PPPoE link.
When I do not use dummynet on router and somebody send a big
(>1492bytes) packet to 212.86.231.58 with DontFragment flag set router
generates ICMP reply message (Fragmentation Needed). This is correct.
But when I use dummynet on that interface:
10170 pipe 10009 ip from any to any out xmit ng4
10175 allow ip from any to any via ng4
10009: 128.000 Kbit/s 0 ms 50 sl. 1 queues (1 buckets) droptail
mask: 0x00 0x00000000/0x0000 -> 0x00000000/0x0000
BKT Prot ___Source IP/port____ ____Dest. IP/port____ Tot_pkt/bytes
Pkt/Byte Drp
0 udp 195.248.191.65/53 212.86.231.58/1118 50965 28380582 0
0 143
router stops sending that ICMP messages. Pipe is not overflowed at that
tme, it is empty.
--
Alexander Motin
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