Harald Welte wrote: > [Cc'ing netdev, since nobody replied since november] > On Wed, Nov 10, 2004 at 12:38:19AM +0100, Henrik Nordstrom wrote: > > A more valid question is why one can not add more than one primary in > > the same subnet. > > > > ip addr add x.x.x.x/y dev eth0 primary > > > > would make sense to me, clearly indicating that these addresses are > > maintained separately. > > agreed. And why I can't even choose which address is primary? > > or put in another way why the addresses automatically become secondary > > addresses to the first added address. > > ... and why does removing the primary address remove all secondary > addresses. This makes it complicated if you have one interface with > multiple ip addresse, that change over time (failover, let's say.) You > don't know yet, which address you need to remove, because you don't know > which of your peers fails. > > So you have all this complicated userspace magic that checks whether the > address that is about to be deleted is the primary, and if yes, re-add > all the other addresses. If if is a secondary, you're happy and only > need to delete that one. > > Can anyone comment what the idea of all this was? This reminds me related issue ... Actually there is concept in Junos software I'd love to see in Linux as well. There is "preferred address" and "primary address" in Junos. Quoting Junos documentation: ************************************************************************** Primary ======= Configure this address to be the primary address of the protocol on the interface. If the logical unit has more than one address, the primary address is used by default as the source address when packets originate from the interface and the destination does not indicate the subnet (ie. multicast destination for example). Default For unicast traffic, the primary address is the lowest non-127 preferred address on the unit. Preferred ========= Configure this address to be the preferred address on the interface. If you configure more than one address on the same subnet, the preferred source address is chosen by default as the source address when you originate packets to destinations on the subnet. Default The lowest numbered address on the subnet is the preferred address. ************************************************************************** Would it be overkill for Linux? From the routers point of view it does make perfect sense. And of course you can manually override defaults in Junos. -- Hasso Tepper Elion Enterprises Ltd. WAN administrator - : send the line "unsubscribe linux-net" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
