From: keith tokash (ktokash@hotmail.com)
Date: Wed Jul 23 2008 - 02:23:49 ART
I've had this happen to me once and another teammate once. I've learned that
the second someone has a multicast problem, tell them to fire up tcpdump and
paste in the output from the sender. My teammate spent about 2 hours looking
at the problem, I heard him complaining so when a different developer with a
different application showed up on our doorstep I checked that pretty close to
first.
The second time was confusing because SSM was working all over, and normal
mcast was working on the same vlan. It turned out to be a bug in some
underlying Java nonsense, and the SSM libraries were written by someone else
in C.
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> From: joe@affirmedsystems.com
> To: gwendel@gmail.com; ccielab@groupstudy.com
> Subject: RE: Interesting issue while testing multicast. TTL value from
linux box.
> Date: Wed, 23 Jul 2008 01:13:44 -0400
>
> That is very nice to know, thanks Greg.
>
> I wonder if this applies to other linux distros as well...
>
> Or can be changed in the ip*.c & .h files and fixed with a recompile?
>
> Anyone?
>
> Thanks,
>
> Joe
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Greg
> Wendel
> Sent: Wednesday, July 23, 2008 12:59 AM
> To: Cisco certification
> Subject: Interesting issue while testing multicast. TTL value from linux
> box.
>
> While testing a multicast setup I ran into an issue where my test linux box
> couldn't work as a multicast source.
>
> The problem ended up being the TTL on the multicast ping packets.
> Apparently the default behavior on my distro, Centos, is to set the TTL to
1
> on multicast pings.
>
> I added the -t flag and magically everything worked.
>
> ping 233.1.1.1 -t 101
>
> Hope this helps someone.
>
> --
> Gregory Wendel, CCIE #20179(R&S)
> Springfield VA, 22153
>
>
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