Subject: Re: Resend: SIOCGIFBRDADDR? - msg#00079

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Resend: SIOCGIFBRDADDR?

I sent this earlier, but I got no reply, and can't seem to find it in the archives. If you reply to this, could you please copy both Kevin Dwyer and myself on the reply? Many thanks! Hi, Some folks using the linux-ha (heartbeat) software have been running into some network-related problems, and Alan Cox suggested that you folks could help us out. One of the ways you can configure linux-ha protocols is to send broadcast packets. In this case, our software needs to get the broadcast address from the OS, so we can proceed. We currently use the SIOCGIFBRDADDR ioctl to do this for us. This has worked pretty well for us for quite some time, but recently some users have run into some problems. It appears that if one configures an interface using ifconfig, then the SIOCGIFBRDADDR ioctl works quite nicely to determine the broadcast address of an interface. However, if one uses the iproute2 tools to configure the interface, then it appears that the SIOCGIFBRDADDR ioctl returns bogus results on that interface. Is this supposed to be the case? Is there a different method we're supposed to use instead of SIOCGIFBRDADDR? Thanks! -- Alan Robertson alanr@xxxxxxx http://linux-ha.org/

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Re: Resend: SIOCGIFBRDADDR?

On Thu, 15 Aug 2002, kuznet@xxxxxxxxxxxxx grunted something like: > You forgot to say what kind of "bogus result" is obtained. Since I'm the one who has primarily been chasing this problem, I'll explain. (cut from my original email...) Specifically, it uses iproute to add aliases to a device, like eth0 in this example: ip -f inet addr add 10.5.5.1 dev eth0 scope link ip -f inet addr add 10.5.5.2 dev eth0 scope link ip -f inet addr add 10.5.5.3 dev eth0 scope link ip -f inet addr add 10.5.5.4 dev eth0 scope link ip -f inet addr add 10.5.5.5 dev eth0 scope link That's all fine, except that it causes really weird stuff to happen to the output of ifconfig. For one, the inet addr: field will change once in a while if I make a modification with ifconfig. That doesn't affect heartbeat, but the Bcast: field is wrongly reported as 0.0.0.0. Now, I know for a fact that I set it correctly when I bring up the interface, prior to using the ip route commands. Once they've been applied, it goes crazy. So my question: Does anyone know if there's an ip route command to make the Bcast field show up as the correct value, or is there a better way for heartbeat to get the broadcast address? (and from a followup email...) # ip addr show eth0 primary scope global 2: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100 link/ether 00:c0:95:e1:bc:64 brd ff:ff:ff:ff:ff:ff inet 10.5.5.8/24 brd 10.5.5.255 scope global eth0 That command gives me the correct broadcast address in the brd field. Correct meaning, the one we're looking for, and would otherwise have gotten if I hadn't used the before-mentioned iproute commands. Any help is appreciated. Thanks. -[ kevin@xxxxxxxxxxx devel.pheared.net ]- -[ Rather be forgotten, than remembered for giving in. ]- -[ ZZ = g ^ (xb * xa) mod p g = h^{(p-1)/q} mod p ]-

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Resend: SIOCGIFBRDADDR?

I sent this earlier, but I got no reply, and can't seem to find it in the archives. If you reply to this, could you please copy both Kevin Dwyer and myself on the reply? Many thanks! Hi, Some folks using the linux-ha (heartbeat) software have been running into some network-related problems, and Alan Cox suggested that you folks could help us out. One of the ways you can configure linux-ha protocols is to send broadcast packets. In this case, our software needs to get the broadcast address from the OS, so we can proceed. We currently use the SIOCGIFBRDADDR ioctl to do this for us. This has worked pretty well for us for quite some time, but recently some users have run into some problems. It appears that if one configures an interface using ifconfig, then the SIOCGIFBRDADDR ioctl works quite nicely to determine the broadcast address of an interface. However, if one uses the iproute2 tools to configure the interface, then it appears that the SIOCGIFBRDADDR ioctl returns bogus results on that interface. Is this supposed to be the case? Is there a different method we're supposed to use instead of SIOCGIFBRDADDR? Thanks! -- Alan Robertson alanr@xxxxxxx http://linux-ha.org/

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Re: Resend: SIOCGIFBRDADDR?

On Thu, 15 Aug 2002, kuznet@xxxxxxxxxxxxx grunted something like: > You forgot to say what kind of "bogus result" is obtained. Since I'm the one who has primarily been chasing this problem, I'll explain. (cut from my original email...) Specifically, it uses iproute to add aliases to a device, like eth0 in this example: ip -f inet addr add 10.5.5.1 dev eth0 scope link ip -f inet addr add 10.5.5.2 dev eth0 scope link ip -f inet addr add 10.5.5.3 dev eth0 scope link ip -f inet addr add 10.5.5.4 dev eth0 scope link ip -f inet addr add 10.5.5.5 dev eth0 scope link That's all fine, except that it causes really weird stuff to happen to the output of ifconfig. For one, the inet addr: field will change once in a while if I make a modification with ifconfig. That doesn't affect heartbeat, but the Bcast: field is wrongly reported as 0.0.0.0. Now, I know for a fact that I set it correctly when I bring up the interface, prior to using the ip route commands. Once they've been applied, it goes crazy. So my question: Does anyone know if there's an ip route command to make the Bcast field show up as the correct value, or is there a better way for heartbeat to get the broadcast address? (and from a followup email...) # ip addr show eth0 primary scope global 2: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100 link/ether 00:c0:95:e1:bc:64 brd ff:ff:ff:ff:ff:ff inet 10.5.5.8/24 brd 10.5.5.255 scope global eth0 That command gives me the correct broadcast address in the brd field. Correct meaning, the one we're looking for, and would otherwise have gotten if I hadn't used the before-mentioned iproute commands. Any help is appreciated. Thanks. -[ kevin@xxxxxxxxxxx devel.pheared.net ]- -[ Rather be forgotten, than remembered for giving in. ]- -[ ZZ = g ^ (xb * xa) mod p g = h^{(p-1)/q} mod p ]-