duplicate MAC - Re: 13.1R problems on Pi3
- Reply: Mark Millard : "Re: duplicate MAC - Re: 13.1R problems on Pi3"
- In reply to: Mark Millard : "Re: 13.1R problems on Pi3"
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Date: Tue, 05 Jul 2022 09:55:56 UTC
Van: Mark Millard <marklmi@yahoo.com> Datum: maandag, 4 juli 2022 20:47 Aan: bob prohaska <fbsd@www.zefox.net> CC: Karl Denninger <karl@denninger.net>, freebsd-arm@freebsd.org Onderwerp: Re: 13.1R problems on Pi3 > > On 2022-Jul-4, at 11:25, bob prohaska <fbsd@www.zefox.net> wrote: > > > On Mon, Jul 04, 2022 at 12:17:15PM -0400, Karl Denninger wrote: > >> > >> On 7/4/2022 11:28, bob prohaska wrote: > >>> On Sun, Jul 03, 2022 at 10:36:35PM -0400, Karl Denninger wrote: > >>> > >>> Can any sense be made of the few ping responses obtained when ntp > >>> is coming up? It's looks as if something happens after ntp runs > >>> that blocks subsequent network traffic, but why starting an outbound > >>> ping should partly unblock things is obscure to me. > >> > >> Yes.?? The odds are reasonably high that there is confusion as to which MAC > >> address maps to which device.?? This implies there's a loop between the two > >> switches (e.g. there is more than one way for packets to get into and out of > >> each said switch to the other) or the two devices are claiming the same MAC > >> address and thus when each "speaks" and performs ARP it "grabs" the map > >> which works until the next one pipes up and it grabs it. > >> > > > > Looks like that's the problem. There's only one cable between switches, but > > here's what I get from ifconfig on each host: > > > > On the machine running 13.1-R attached to switch 2: > > bob@www:~ % ifconfig > > lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384 > > options=680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6> > > inet6 ::1 prefixlen 128 > > inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1 > > inet 127.0.0.1 netmask 0xff000000 > > groups: lo > > nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL> > > ue0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 > > options=80009<RXCSUM,VLAN_MTU,LINKSTATE> > >>>>>>>> ether b8:27:eb:71:46:4e > > inet 50.1.20.28 netmask 0xffffff00 broadcast 50.1.20.255 > > media: Ethernet autoselect (100baseTX <full-duplex>) > > status: active > > nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> > > bob@www:~ % hostname > > www.zefox.org > > bob@www:~ % > > bob@www:~ % uname -a > > FreeBSD www.zefox.org 13.1-RELEASE FreeBSD 13.1-RELEASE releng/13.1-n250148-fc952ac2212 GENERIC arm64 > > bob@www:~ % > > > > On the machine running an updated stable/13 system attached to switch 1: > > bob@pelorus:~ % ifconfig > > lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384 > > options=680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6> > > inet6 ::1 prefixlen 128 > > inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1 > > inet 127.0.0.1 netmask 0xff000000 > > groups: lo > > nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL> > > ue0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 > > options=80009<RXCSUM,VLAN_MTU,LINKSTATE> > >>>>>>> ether b8:27:eb:71:46:4e > > inet 50.1.20.24 netmask 0xffffff00 broadcast 50.1.20.255 > > media: Ethernet autoselect (100baseTX <full-duplex>) > > status: active > > nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> > > bob@pelorus:~ % hostname > > pelorus.zefox.org > > bob@pelorus:~ % > > bob@pelorus:~ % uname -a > > FreeBSD pelorus.zefox.org 13.1-STABLE FreeBSD 13.1-STABLE #6 stable/13-n251601-2353343b324: Sun Jul 3 21:43:04 PDT 2022 bob@pelorus.zefox.org:/usr/obj/usr/src/arm64.aarch64/sys/GENERIC arm64 > > > > > > Thinking it over, I added the extra switch some time ago and didn't > > immediately notice any problems. Both Pi3s started out on the first > > switch (NetGear), with no obvdious problems. Later I probably moved > > one Pi3 to the second switch (D-Link) and started to notice troubles. > > Does this story make sense? > > > >> Each interface device from the factory is supposed to have a unique MAC > >> address.?? This can, for most interfaces, be overridden (modern Android > >> phones "randomize" it if told to as a "security" measure) but for obvious > >> reasons doing that can lead to problems. Collisions where multiple devices > >> are using the same MAC will lead to exactly the sort of thing you're seeing > >> because the switch is sending the packets to the wrong place. > >> > >> I've got a decent number of Pis of everything back to the "2" here and most > >> of the time several of them are on my network at once.?? I've not seen this > >> problem but I wouldn't exclude that both are claiming the same MAC and, if > >> so, that's what's causing the problem. > >> > > [example ifconfig output snipped] > >> > >> That MUST be unique on your LAN; the prefix (first three octets) is a vendor > >> code /*and the last three should never be duplicated by a vendor. */If you > >> are not setting it in /etc/rc.conf or elsewhere and there /are /duplicates > >> then a very bad thing happened when those units were manufactured -- set one > >> of them to something else. > >> > > > > Any pointers to MAC-setting methods appreciated..... > > My example is not the best fit because it is for DHCP > but in /etc/rc.conf I use (but showing "??"s): > > ifconfig_dwc0="ether ??:??:??:??:??:?? DHCP" > > to avoid its random assignment at power up. > > So for you I would guess: > > ifconfig_ue0="ether ??:??:??:??:??:?? inet 50.1.20.28 netmask 255.255.255.0" > > > === > Mark Millard > marklmi at yahoo.com > > > > > Hi, My Rpi3B+ does not have a random MAC on ue0. NB: It uses the muge driver: # devinfo | more ... bcm283x_dwcotg0 usbus1 uhub0 uhub1 uhub2 muge0 miibus0 ukphy0 ... Your current MAC is officially from the Raspberry Pi Foundation: https://hwaddress.com/oui-iab/B8-27-EB/ . Could you have hardcoded the MAC in a *.dtb file or other config in the /boot directory and copied that over to the other RPI? If you are going to assign some MAC yourself take a look at https://en.wikipedia.org/wiki/MAC_address#Universal_vs._local_(U/L_bit) to choose a locally administered MAC. Regards, Ronald.