Hi Luke,
Just to be my annoying self -- this is the kind of thing that it would
be great to have a short memo about. The steps aren't complicated, but
you do have to get everything right at the switch / receive-side for
things to work.
Speaking to your original question -- the latest ROACH2 library
(roach2 branch of mlib_devel) supports multicast sending (and
receiving, though I've never used that). I believe I've used multicast
tx on an Arista 7050QX-32 switch and a Mellanox SX1012 to good effect.
Needless to say, I didn't write the above memo which I'm gently
suggesting you do.
:)
Good luck!
Jack
On Mon, 28 Jan 2019 at 09:36, David MacMahon wrote:
>
> Hi, Luke,
>
> I have not used a ROACH2 to send multicast packets, but the MeerKAT folks
> certainly have. My understanding is that the 10 GbE block does the proper
> mapping of multicast destination IP address to multicast destination MAC
> address so it should "just work".
>
> I recommend starting with a direct connection between a ROACH2 and a PC.
> That way the PC's NIC will get the packets without having to interact with an
> intervening switch. That will let you examine the packets using tcpdump or
> wireshark. To get the kernel to pass the multicast packets up the network
> stack, I think you will still need to use the IP_ADD_MEMBERSHIP socket option
> (see "man 7 ip" for details). When you have that working, then you can add a
> switch into the path. The IP_ADD_MEMBERSHIP option will inform the switch
> (via IGMP) of the multicast group (i.e. address) that you wish to receive
> packets for.
>
> HTH,
> Dave
>
> > On Jan 28, 2019, at 08:08, Luke Hawkins wrote:
> >
> > CASPERites,
> >
> > Has anybody been using ROACH2s to transmit multicast packets?
> >
> > I found the following two threads on the mailing archive, and was
> > wondering if the 10GbE blocks had been updated since then in ways that
> > could impact multicasting, or if anybody had any comments on preferred
> > IGMP snooping switches, etc...
> >
> > https://www.mail-archive.com/casper@lists.berkeley.edu/msg06132.html
> > https://www.mail-archive.com/casper@lists.berkeley.edu/msg04527.html
> >
> > -Luke Hawkins
> >
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