possible bug in arp-cache management

Hans Bulfone (jsb@jsb.priv.at)
Fri, 28 Aug 1998 16:21:40 +0200


Hi!

I've tried the following with 2.0.33, 2.0.34
and 2.0.35 with the same result.

To solve gated-routing-probs (gated doesn't accept
static routing entries that route a network over a
gateway that isn`t in the same subnet as the
ip-adress of the interface it gets routed through)
I had the idea to set up point to point links to
these gateways:

ifconfig eth0:0 some_ip_adress pointopoint adress_of_the_gw netmask of_the_primary_adress -broadcast
and so on ...

The problem is, when I use the same local ip-adress
on all of these "ethernet-pointopoint-links" the following
happens:

I want to ping a.b.c.d that is reachable over eth0:2 .
The kernel sends an arp-query and notes
a.b.c.d incomplete eth0:2
in its arp-cache.

The answer is sent to the local ip-adress of these interfaces.
The kernel receives the answer and stores it in his arp-cache
with interface eth0:0 (the first interface with the same local
ip-adress). So I have

a.b.c.d incomplete eth0:2
a.b.c.d 12:34:56:78:9A:BC eth0:0

But the kernel still doesn´t know where to send its ping-packet.

Wouldn´t it be better to store and retrieve arp-entries only
with the primary interface name (eth0) since it's the
same physical interface anyway ?

cu Hans Bulfone.

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