Pokotilenko Kostik (approximate romanization) wrote : > > We have two building with local networks connected by Zyxel Prestige 841 > and 841C VDSL-modems. They work in transparent bridge mode. > > On one end 841 is connected directly to a switch. On other 841C > connected to a linux router wich is also connected to a switch, and > those interfaces bridged. So is it a bridge or a router ? > There is a problem, when a computer is being moved from one building to > another it stops seeing other end of the bridge until modems are > rebooted. Can you elaborate "stops seeing" ? Packet captures of ARP and IP traffic on both ends might provide more information. > I was thinking the problem is in modems' part, but in Zyxel support I've > been told they are just dumn transparent bridges and doesn't behave like > that. A bridge (or a switch) is never completely as dumb as a hub. It uses a MAC-port table in order to forward frames only through the relevant ports. > So, the only device left that may cause such problem is linux > router/bridge. > > Is there any kind of behaviour of linux bridge (ebtables) that may cause > such problem? The Linux bridge maintains a MAC-port table based on the source MAC address in received frames. As expected, if a MAC address was associated to a given port and a frame from that MAC address is received on a different port, then the table is updated accordingly. Besides, rebooting the modems and not the Linux box fixes the problem. So I doubt that the Linux bridge causes the problem. Of course the update process requires that the moved box sends traffic first. If it just sits there waiting then MAC-port tables won't be updated, until the entry eventually expires. > P.S. there is no ebtables rules at all, no iptables related rules. Then may I ask what is the purpose of this box ? -- To unsubscribe from this list: send the line "unsubscribe netfilter" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
