[lvs-users] broadcast address for VIP

linbo liao llbgurs at gmail.com
Mon Dec 26 00:54:02 GMT 2016


Thank you for the clarification. This does make sense.

Thanks,
Linbo

2016-12-25 18:52 GMT+08:00 Julian Anastasov <ja at ssi.bg>:

>
>         Hello,
>
> On Sun, 25 Dec 2016, linbo liao wrote:
>
> > I saw most of example will configure broadcast address for VIP, and
> > broadcast address is same as VIP.  Like VS-DRouting
> > <http://www.linuxvirtualserver.org/VS-DRouting.html>.
> >
> > Refer to netmask for VIP
> > <http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.
> ipvsadm.html#netmask_for_VIP>,
> > netmask should be 255.255.255.255. But for broadcast , I can't figure out
> > the reason, why should set broadcast same as vip address explicitly ?
>
>         Do not provide broadcast address when configuring VIP.
> As VIP is part from some subnet, the broadcast addresses are
> automatically generated by the kernel when the primary (first)
> IP in subnet was added, see fib_add_ifaddr() for reference.
> VIPs should be configured with /32 (255.255.255.255 netmask),
> so no broadcast is created for them, for example:
>
> 1. add RIP/24 on eth0 (first and last address are created as broadcasts)
> 2. add VIP/32 on lo (for real server) or on eth0 (for director)
>
> Regards
>
> --
> Julian Anastasov <ja at ssi.bg>
>


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