Date: Wed, 23 Oct 2002 14:41:19 -0400 From: Charlie Root <ericx@vineyard.net> To: freebsd-net@freebsd.org Subject: VLAN problems with replies to broadcast Message-ID: <20021023184119.3980891F68@vineyard.net>
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We have built a machine with 3 vlan parenting off an fxp. The vlan
are bridged and vlan0 has an IP. The fxp has no IP and is excluded
from the bridge group.
** root@fw ** ~ ** Sat Oct 19 18:38:08
# ifconfig
fxp0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
ether 00:02:b3:5b:dd:98
media: Ethernet autoselect (100baseTX <full-duplex>)
status: active
vlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet 192.168.10.1 netmask 0xffffff00 broadcast 192.168.10.255
ether 00:02:b3:5b:dd:98
vlan: 5 parent interface: fxp0
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
inet 127.0.0.1 netmask 0xff000000
vlan1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
ether 00:02:b3:5b:dd:98
vlan: 10 parent interface: fxp0
vlan2: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
ether 00:02:b3:5b:dd:98
vlan: 20 parent interface: fxp0
The fxp is plugged into an SMC Tigerswitch. The SMC is configured to
pass VLAN's 5, 10 and 20.
Everything works except replies to broadcast packets.
e.g. using tcpdump I observe an arp request coming from the SMC
switch. tcpdump reports that there are 3 packets (one tagged with each
VLAN -- not clear whether there really are 3 distinct packets or
whether tcpdump is make a best-effort to report a broadcast packet).
tcpdump also displays a single reply tagged with the one correct VLAN
(the remote host's traffic is tagged by the SMC). The remote host does
not receive the reply. Presumably the SMC is not forwarding the
packet.
The same behaviour is observable for dhcp requests.
Is there some reason why a packet sent in reply from a VLAN interface
might be tagged differently such that the SMC would refuse it?
Has anyone else observed such behaviour?
Can anyone suggest some tests I might try or further reading?
Thank you for your time.
--ericx
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