All-subnets-directed Broadcast

Manie Steyn msteyn at
Fri Aug 11 08:55:02 EST 2000


This is not necessarily an embedded question, so please direct me to a
different forum dealing with  Linux Network programming if none here can
help me.

I have 4 100baseT interfaces on my MCP750, each configured for a different
192.168.x subnet.

sh-2.03# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface     *        U     0      0        0 eth3     *        U     0      0        0 eth2     *        U     0      0        0 eth1     *        U     0      0        0 eth0

I am trying to send a broadcast message (as rudimentary synchronization) to
all subnets at the same time. I believe this is called "All-subnets-directed
Broadcast" [from Stevens], and should be possible if the application and
router supports this.

To test this I use ping but receives "Network is
unreachable" error:

sh-2.03# ping -c 1
PING ( 56 data bytes
ping: sendto: Network is unreachable
ping: wrote 64 chars, ret=-1

--- ping statistics ---
1 packets transmitted, 0 packets received, 100% packet loss

I have also tried ping and ping with same
Ping 192.168.x.255 works for broadcasting on each of the subnets, is called
"Subnet-directed Broadcast" [from Stevens].

I'm sure it must be possible to broadcast to all configured subnets somehow.
Does the problem lie with the router or ping. (Maybe I should stop being
lazy and go write a small tester to check it out :-)

Any suggestions in the mean time?


Manie Steyn     Embedded Software Engineer       mailto:msteyn at
Western Multiplex, 1367 Redwood Way, Petaluma, CA  Ph:707 792 5390 x 12

** Sent via the linuxppc-embedded mail list. See

More information about the Linuxppc-embedded mailing list