Re: Multicast on loopback?

From: Erik G. Burrows (
Date: Wed Feb 14 2001 - 14:16:21 EST

> > locally over the loopback interface. This does not work without adding a
> > bogus route statement to get the kernel to hand up the packets from
> > loopback to my waiting application.
> The multicast ABI includes the ability to toggle loopback of multicast
> datagrams. Use the socket options instead

I read that multicast loopback is by default enabled, and I have witnessed
this, when having my application bind to my ethernet interface, but the
datagrams do not seem to be looped back when I bind to the 'lo' interface.

Could this possibly be a conflict with the inherently 'looped back'
behavior of the loopback net driver?

As far as toggling the flag, or even reading it, I cannot, as I am
developing in Java.

For developing, I can easily kludge it to work, by adding a fake route
statement, forcing the packets back up to the application, but I want to
make sure the differing behavior is not a bug in the kernel networking

-Erik G. Burrows

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This archive was generated by hypermail 2b29 : Thu Feb 15 2001 - 21:00:25 EST