Reliable Multicast (SRM) in ns

["T.Hval" <th1@ukc.ac.uk>]

Hi!
I'm trying to get an understanding of the SRM functionality in ns, so I
have some questions concerning SRM.
Why do the data packet's show up as cbr packets(In nam) when I use a
(simulated)telnet session as a data generator? 
Why can't I see any acknowledgments?(It is supposed to be reliable so
there ought to be some ack's)
How can I change the mode of SRM (between sparse, dense mode and
centralized multicast)?
Can anybody give me some indication what these errors(se below) are
caused by when I try to use an FTP session as a data generator ?
(according to the documentation I can use any traffic generation module to
generate data, isn't FTP considered to be an traffic generation module?)

ns: _o299 start: _o298: invalid send request -1
    (_o298 cmd line 1)
    invoked from within
"_o298 cmd send -1"
    invoked from within
"catch "$self cmd $args" ret"
    (procedure "_o298" line 2)
    (SplitObject unknown line 2)
    invoked from within
"[$self agent] send -1"
    (procedure "_o299" line 2)
    (Application/FTP start line 2)
    invoked from within
"_o299 start"


Thanks

Tor Hval