Subject: Re: Incorrect ARP behavior when multiple/none IPv4 address assigned to interface

From: Sergey Popovich <[email-masked]>
Date: Wed, 24 Oct 2012 13:37:36 +0300

Julian Anastasov пишет:

> 	dummy module is usually used as blackhole for
> traffic or to hide addresses from other interfaces with
> some sysctl interface flags.
>
> 	For example, can it work in this way?:
>
> eth0: addr 10.0.1.1/24
> ip route 10.0.1.2/32 dev eth0 src 10.0.1.1
>
> eth1: addr 10.0.1.1/24
> ip route 10.0.1.3/32 dev eth1 src 10.0.1.1
>
> eth2: addr 10.0.2.1/24
> ip route 10.0.2.2/32 dev eth2 src 10.0.2.1
>
> 	By this way we have subnet on every device and
> we can prefer local IP from such subnet in inet_select_addr.
> May be arp_ignore=1/2 and arp_announce=1/2 can help here
> to put the needed restrictions, i.e. we should not expose
> addresses from other devices. It should not cause problem
> for proxy_arp because we have more specific /32 routes.
>

Yes, just apply proposed configuration to lab schema.

Everything works as expected with no extra arp_ignore/arp_announce
configuration. Even if I add second primary address 192.168.1.1/24 to 
eth2, and introduce pc4 in same broadcast domain as pc3 (eth2).

Well, configuration with 3000 subinterfaces looks worse, but it works
with no extra patches/configuration.

Thank you for your help.

-- 
SP5474-RIPE
Sergey Popovich