Date: Sun, 22 Sep 2019 23:50:47 +0900 (JST) From: Hiroki Sato <hrs@allbsd.org> To: akgupt3@gmail.com Cc: freebsd-net@freebsd.org, hrs@FreeBSD.org Subject: Re: Link flap for setting ether/MAC address Message-ID: <20190922.235047.562191741306834004.hrs@allbsd.org> In-Reply-To: <CALnRwMR7qKqzq3j8-YGOAFhZN-u6g1o=s4LjnsLJZ1x=oRAHAw@mail.gmail.com> References: <CALnRwMR7qKqzq3j8-YGOAFhZN-u6g1o=s4LjnsLJZ1x=oRAHAw@mail.gmail.com>
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----Security_Multipart(Sun_Sep_22_23_50_47_2019_632)-- Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Anish <akgupt3@gmail.com> wrote in <CALnRwMR7qKqzq3j8-YGOAFhZN-u6g1o=s4LjnsLJZ1x=oRAHAw@mail.gmail.com>: ak> Hi all, ak> Got a very basic question, why physical link is flapped when we set the ak> address ak> ak> # dmesg -c ak> # ifconfig ix1 ether 70:6d:15:1f:12:72 ak> ..wait.. ak> # dmesg ak> ix1: link state changed to DOWN ak> ix1: link state changed to UP ak> # ak> ak> is this a bug or expected behavior? We could update our MAC in next ARP ak> request without link flap or some other system like switch etc expect the ak> link flap to update ARP. Is this the behavior for other systems? I think this depends on the driver. Some drivers reset the NIC when the MAC address is changed mostly because it is an easy way to re-configure the multicast filtering rules or the other settings which must be updated for the new MAC address. It causes a link flap. For upper layers above the NIC driver, you are correct. -- Hiroki ----Security_Multipart(Sun_Sep_22_23_50_47_2019_632)-- Content-Type: application/pgp-signature Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iMcEABMKAC0WIQRsDSNTJ8+Ax5Ae/dLbsH3Gbx9zfwUCXYeKRw8caHJzQGFsbGJz ZC5vcmcACgkQ27B9xm8fc3+yZAII89E4Kh/Q7hEOPIZt0xgjtnCsG9cxrcHGLRjE bJ3Jo/z1EgBdqpj7TWzgQdhnOm75oaI5bNphJNmtJlBdEjVjd6ICCOiGEUUvRapX VrH7nRJg7TNMF0KFZd4nM9P9TioMSQfzo0S/eIK6TT8O+bG3iibNdNBlfosVmC1Y mEUOE7cDElOs =pY5S -----END PGP SIGNATURE----- ----Security_Multipart(Sun_Sep_22_23_50_47_2019_632)----
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