Some help with broadcasts through a Linux system

Dan Kaminsky effugas at
Wed Feb 3 13:24:23 GMT 1999

>> It seems that Linux feels that it should not have to forward the
>> datagrams.
>Correct. You don't forward broadcasts. Imagine what ping
>do if you did


    If a Linux machine recieves a ping, it should not
redistribute to all interfaces *unless configured to*.

    Is it always bad to bridge broadcasts between subnets?  Yes, it's
probably a Less Than Ideal(TM) scenario to have information flying around
via broadcasts a la NetBIOS, but you have to admit it *does* reduce point of
failure issues substantially--we're still working on bringing fault
tolerance to Samba WINS.

    3Com hubs support broadcast bridges, at least by port, using the UDPHELP
service.  It'd be nice to see this kind of functionality as part of Linux.

    Bah, one final note--if broadcast traffic is low but point to point
traffic is high, then broadcast bridging is far preferable to true bridging,
since true bridging multiplies the internet subnet point to point traffic
through every subnet, whereas broadcast bridging just moves the required
information(say, NetBIOS broadcasts).

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