Date: Fri, 17 Mar 2006 20:59:44 -0800 From: Glenn Dawson <glenn@antimatter.net> To: ray@redshift.com, freebsd-hackers@freebsd.org Subject: Re: strange ARP problem Message-ID: <7.0.1.0.2.20060317205230.057ba948@antimatter.net> In-Reply-To: <3.0.1.32.20060317203432.00bf8a40@pop.redshift.com> References: <441B09DA.1010902@elischer.org> <200603171502.k2HF2IV3086523@pinky.frank-behrens.de> <20060317151220.GA26987@britannica.bec.de> <441B09DA.1010902@elischer.org> <3.0.1.32.20060317203432.00bf8a40@pop.redshift.com>
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At 08:34 PM 3/17/2006, ray@redshift.com wrote: >I'm having a strange issue here and thought maybe someone on this list might >have some ideas. I have tried to figure it out for a couple of days, but no >luck yet. The problem seems to be around reporting of arp information. > >Here is my basic config. I have my workstation (a windows XP box) with 2 IP's >on a private network segment (both with /24 subnet masks) > >192.168.10.250 >192.168.20.250 > >the 10.250 and 20.250 are connected out to a small switch. Also connected to >that small switch is a mail server as shown below. > >[ workstation ] [ mail server ] >[192.168.10.250]-------[ small ]--------[ 192.168.10.15] >[192.168.20.250]-------[ switch ]--------[ 192.168.20.15] > | > | > [router 192.168.10.1] > | > public IP > >10.15 handles SMTP to the public, 20.15 is for admin and POP to/from the >workstation on 20.250 > >Okay, so the problem is that when I fire up the Workstation (it's running >Windows XP), the arp data for 192.168.20.15 comes back with the incorrect Mac >address. It ends up with the Mac address for 10.15, instead of 20.15 - which >keeps the machines from talking correctly. If you delete the ARP table and >re-arp, then it's perfectly fine from then on. Totally odd. > >Then the other night I noticed the following errors (see below) from the mail >server. It seems to be related, but I can't pin point the source or >what might >cause something like this. > >Does anyone have any ideas what could be causing this? > > > arp: 192.168.10.1 is on fxp0 but got reply from 00:30:48:52:08:03 on bge0 > > arp: 192.168.20.250 is on bge0 but got reply from 00:e0:81:32:e0:a0 on fxp0 > > arp: 00:30:48:51:ce:f0 is using my IP address 192.168.20.15! > > arp: 00:30:48:51:ce:f0 is using my IP address 192.168.20.15! > > arp: 192.168.10.1 is on fxp0 but got reply from 00:30:48:52:08:03 on bge0 > > arp: 00:30:48:51:ce:f0 is using my IP address 192.168.20.15! > > arp: 192.168.10.15 is on lo0 but got reply from 00:30:48:51:ce:f0 on bge0 > > arp: 192.168.10.1 is on fxp0 but got reply from 00:30:48:52:08:03 on bge0 > > arp: 192.168.10.15 is on lo0 but got reply from 00:30:48:51:ce:f0 on bge0 > > arp: 192.168.20.250 is on bge0 but got reply from 00:e0:81:32:e0:a0 on fxp0 > > arp: 192.168.10.15 is on lo0 but got reply from 00:30:48:51:ce:f0 on bge0 > > arp: 192.168.10.1 is on fxp0 but got reply from 00:30:48:52:08:03 on bge0 > >here is the ifconfig from the mail server: > >[ray@mail ray]$ ifconfig >fxp0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 > inet 192.168.10.15 netmask 0xffffff00 broadcast 192.168.10.255 > ether 00:30:48:51:ce:f0 > media: Ethernet autoselect (100baseTX <full-duplex>) > status: active >bge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 > options=1b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING> > inet 192.168.20.15 netmask 0xffffff00 broadcast 192.168.20.255 > ether 00:30:48:51:ce:f1 > media: Ethernet autoselect (100baseTX <full-duplex>) > status: active >lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384 > inet 127.0.0.1 netmask 0xff000000 > >If anyone has any idea, please let me know. Thanks! This is exactly why it's ill-advised to have two network interfaces on different networks connected to the same physical network. If you actually need two different networks (although from your description I don't see a reason why you would) then use a single physical interface and assign it an IP from each network. Or, get a switch that has VLAN capabilities and keep the two networks separated. -Glenn >Ray > >_______________________________________________ >freebsd-hackers@freebsd.org mailing list >http://lists.freebsd.org/mailman/listinfo/freebsd-hackers >To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org"
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