Date: Tue, 12 Feb 2013 18:32:12 +0100 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-net@freebsd.org Subject: Problems with two interfaces on the same subnet? Message-ID: <kfduar$qrh$1@ger.gmane.org>
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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigC6E188A6C46F1F31B3AC1DAF Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Hello, I have a machine with two interfaces, igb2 and igb3 on the same subnet but with different IP addresses, e.g. igb2 has 192.168.1.221, igb3 has 192.168.1.222. Firstly, is there anything which would preclude this from working? As I see it, these are two different MAC addresses and to the outside world should look as two different hosts, right? I currently don't have the right tools to diagnose this, I'm using nas4free which is a 9.1-based "embedded" system lacking tcpdump, so here are some raw observations: * With both NICs connected to the same switch, everything appears to work, but an *upstream* router *seems* to have strange issues which manifest in it replicating the traffic coming from this machine to unrelated ports. This router is an old, unsupported Cisco router which should have long be replaced and no-one here knows how to debug it. The network admin says that he sees that the "Cat4k Mgmt LoPri" counter shows high CPU usage, but cannot help other than that. This also may be due to weirdness in other parts of the network, we don't know if it's caused by my machine. * With both NICs connected to different switches, everything appears to work, BUT, if igb2 cable is disconnected, pings to igb3 simply stop, even though its cable *is* still connected. This sort of looks like incoming and outgoing traffic to the same IP address (that of igb3) are arriving and departing on separate ports, which I could accept as the packets are unrelated on the IP level and the route says that the subnet is reachable only through the first interface, if the kernel does nothing when the first NIC's link goes down. Is this what's going on? The reason why I have two addresses on the same subnet is for poor-man's load-balancing, this is a NFS server and I'd like to use both NICs at the same time, accessed from different client machines. I'm suspiocious that the network equipment I'm using does not support LACP. Is there another way to do it? Would it help to have two different private subnets= ? And the big question on my network admin's mind: would it help to switch to Linux? --------------enigC6E188A6C46F1F31B3AC1DAF Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAlEafJ4ACgkQ/QjVBj3/HSyG/wCeKfNDOwAhmc+FzzVZefHuHtel XDEAni1pm2l/9Tmj6MdKw3TuFPXBknUT =WUG6 -----END PGP SIGNATURE----- --------------enigC6E188A6C46F1F31B3AC1DAF--
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