[Xorp-users] ASM or SSM

[Pavlin Radoslavov]

> With Xorp I can use multicast but i have a question; How do I know if I am 
> using ASM or SSM? and How do I configure to use just one of these?.

Your application decides whether to use ASM or SSM.
Note that the default IGMP version used by XORP is IGMPv2 (i.e., ASM
only). If you want to enable SSM support as well, then you need to
set the IGMP version (per vif) to 3.

You could use the "show igmp group" xorpsh command to see various
information about the directly-connected multicast receivers (one
line per group or source-group). The output contains the IGMP
version as well.

Finally, I should note that the 232.0.0.0/8 multicast address space
is reserved for SSM. Hence, eventually any multicast traffic in that
address space is suppose to be SSM (and no ASM traffic should use
232/8). However, currently this distinction is not enforced by XORP,
and I don't know whether it is enforced by other router vendors or
OS (IGMP host stack) implementations.

Regards,
Pavlin