On Wed, 2017-05-31 at 08:32 -0700, Ben Pfaff wrote: > On Wed, May 31, 2017 at 11:39:28AM +0200, Matthias May wrote: > > On 27/05/17 04:29, Hunt Xu wrote: > > > On Fri, May 26, 2017 at 11:46 PM, Ben Pfaff <[email protected]> wrote: > > >> It's becoming more common that OSes include "ip" but not "ifconfig", so > > >> it's best to avoid using the latter. This commit removes most references > > >> to "ifconfig" and replaces them by "ip". It also adds a build-time check > > >> to make it harder to introduce new uses of "ifconfig". > > >> > > >> Signed-off-by: Ben Pfaff <[email protected]> > > >> --- > > > > > > <snip> > > > > > >> diff --git a/Documentation/faq/issues.rst b/Documentation/faq/issues.rst > > >> index c60336a10569..82d0605da125 100644 > > >> --- a/Documentation/faq/issues.rst > > >> +++ b/Documentation/faq/issues.rst > > >> @@ -43,8 +43,8 @@ eth0. Help! > > >> itself. For example, assuming that eth0's IP address is > > >> 192.168.128.5, you > > >> could run the commands below to fix up the situation:: > > >> > > >> - $ ifconfig eth0 0.0.0.0 > > >> - $ ifconfig br0 192.168.128.5 > > >> + $ ip addr flush dev eth0 > > >> + $ ip addr add 192.168.128.5 dev br0 > > > > > > ip addr add 192.168.128.5/24 dev br0 > > > > > > It seems using ifconfig without specifying any netmask the > > > netmask/prefixlen > > > will still be properly set (not diving quite deep, but strace indicates > > > that > > > this is not done by ifconfig, ifconfig don't even try to set the netmask), > > > whlie using ip-address with only the address specified the prefixlen is > > > always 32. > > > > > > Some tests on my Ubuntu 16.04: > > > 1a. ifconfig br0 192.168.128.5 -> br0 gets 192.168.128.5/24 > > > 1b. ip addr add 192.168.128.5 dev br0 -> br0 gets 192.168.128.5/32 > > > 2a. ifconfig br0 172.16.128.5 -> br0 gets 172.16.128.5/16 > > > 2b. ip addr add 172.16.128.5 dev br0 -> br0 gets 172.16.128.5/32 > > > 3a. ifconfig br0 10.0.128.5 -> br0 gets 10.0.128.5/8 > > > 3b. ip addr add 10.0.128.5 dev br0 -> br0 gets 10.0.128.5/32 > > > > > >> > > *snip* > > > > You might want to consider to add brd + to the ip command. > > E.g. ip addr add 192.168.128.5/24 brd + dev br0 > > > > Without: > > 7: br0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default > > qlen 1000 > > link/ether 1a:78:fe:72:9c:be brd ff:ff:ff:ff:ff:ff > > inet 192.168.128.5/24 scope global br0 > > valid_lft forever preferred_lft forever > > > > With: > > 7: br0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default > > qlen 1000 > > link/ether 1a:78:fe:72:9c:be brd ff:ff:ff:ff:ff:ff > > inet 192.168.128.5/24 brd 192.168.128.255 scope global br0 > > valid_lft forever preferred_lft forever > > > > As you can see the broadcast address isn't set without. > > > > I see you already posted a v4 but this comment seems more appropriate in > > this thread. > > What happens if no broadcast address is specified? I've never seen > instructions say that one should specify this, so I really wonder > whether it is necessary.
My understanding of this is that the brd command is used to over ride the broadcast address that would normally be computed by specifying the IP/CIDR. I don't think it is necessary and I don't generally specify it in normal usage. Thanks, - Greg > _______________________________________________ > dev mailing list > [email protected] > https://mail.openvswitch.org/mailman/listinfo/ovs-dev _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
