Date: Mon, 2 Apr 2018 16:07:49 +0300 From: Daniel Braniss <danny@cs.huji.ac.il> To: Harry Schmalzbauer <freebsd@omnilan.de> Cc: freebsd-virtualization@freebsd.org Subject: Re: bhyve and arp problem Message-ID: <F4600452-0BFA-4A8A-B101-54333C8EF6F6@cs.huji.ac.il> In-Reply-To: <5AC22328.8060306@omnilan.de> References: <DEA10FBE-E8F8-46C3-816C-DB61421BF0A5@cs.huji.ac.il> <5AC22328.8060306@omnilan.de>
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> On 2 Apr 2018, at 15:33, Harry Schmalzbauer <freebsd@omnilan.de> wrote: > > Bezüglich Daniel Braniss's Nachricht vom 30.03.2018 13:16 (localtime): >> hi, >> this is my first attempt at bhyve, and so far all seems ok, except >> in my guest, the mac address of the hosting keeps flipping, ie, every 20 minutes >> i see a message : >> … arp: nnn (the hosting ip) moved from xxxx to yyyy >> on both the host and guest I’m running a very resent -stable. >> the yyyy is the mac of the host nic, while the xxxx is the tap0 >> >> i know this looks harmless, but it’s annoying > > You can calm it with > 'sysctl net.link.ether.inet.log_arp_movements=0' > > There's also "net.link.ether.inet.log_arp_wrong_iface" and > "net.inet.ip.check_interface" which influence related behaviour. > > You also posted (documentationized IP-addresses): >> I think the problem starts with the host seeing the client/guest on 2 interfaces, the nic (mlnxen0) and the tap(tap0) >> on the host: >> >> arp -a >> ... >> bhv-00.cs.huji.ac.il (192.0.2.246) at xx.xx.xx.xx.xx on tap0 expires in 1001 seconds [ethernet] >> bhv-00.cs.huji.ac.il (192.0.2.246) at xx.xx.xx.xx.xx on mlxen0 expires in 644 seconds [ethernet] > the above 2 lines are on the host running bhyve (server?) and the MACs belong to the client, and they are identical, there is no complaints. (BTW, did you change the ip’s?) > Initially, you reference two MAC-addresses with xxxx and yyyy. this is on the client, where the MAC are different (it’s of the hosting computer). > The recent post indicates non-different MAC-addresses. > > If xxxx and yyyy - resp. xx.xx.xx.xx.xx - are equal (but seen on > different interfaces), this wouldn't get logged I think. > But it was the only harmless case for straight forward setups. > Even with STP/LACP/CARP/etc. in place, "arp: IP-address moved" always > indicates a misconfiguration and I don't know any example where the two > different MAC-Addresses for one IP-address were harmless. > While using a single (locally administrated?) MAC address more than once > sitewide _can_ make sense, having two interfaces on one host which both > are on the same ethernet segment like the two interfaces with the same > MAC address, looks like an unintended setup. > > So I strongly suggest to analyze your setup before altering the > mentioned sysctl!!! > I do want to know if there are ip/mac issues, it usually happens when more than one host has the same ip, which is not the case here :-( thanks, danny > -harry
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