[LARTC] iproute2 and routing entries

[Martijn van Oosterhout kleptog@cupid.suninternet.com]

<PRE>bert hubert wrote:
&gt;<i> 
</I>&gt;<i> On Thu, Nov 02, 2000 at 06:35:48PM +0100, Michael Schoen wrote:
</I>&gt;<i> &gt; Hi guys,
</I>&gt;<i> &gt;
</I>&gt;<i> &gt; i am just playing around with iproute2 and some questions came to my mind.
</I>&gt;<i> &gt;
</I>&gt;<i> &gt; I´m wondering why I get a route entry for the subnet of eth0s primary addr
</I>&gt;<i> &gt; if I use the command &quot;ip link set eth0 up&quot;.
</I>&gt;<i> &gt;
</I>&gt;<i> &gt; I´m personally not a friend of such behaviour, because I often need some
</I>&gt;<i> &gt; strange routing set-ups. Is it possible to avoid this behaviour, meaning I
</I>&gt;<i> &gt; only get routing entries if I really set them by myself?
</I>&gt;<i> 
</I>&gt;<i> This behaviour has been hotly contested on the linux kernel mailinglist,
</I>&gt;<i> perhaps the archives can tell you if there is a way around this.
</I>
The reason is that by setting an interface with the IP address A and netmask
B you are implying that there is a network attached with the network address
A&amp;~B with the given netmask and so a route should be added appropriately.

The last I heard was that one of the networking guys gave this explanantion
and challenged someone to give an example of where this was the wrong
thing to do. The thread died there IIRC.

Personally I think it's a great feature because in at least 99.99% of 
cases it's exactly what you want and I havn't found an example of the
other 0.01%.

-- 
Martijn van Oosterhout &lt;<A HREF="mailto:kleptog@cupid.suninternet.com">kleptog@cupid.suninternet.com</A>&gt;
<A HREF="http://cupid.suninternet.com/~kleptog/">http://cupid.suninternet.com/~kleptog/</A>


</PRE>