Contrary to what BrowserUK said, it seems like your usage is consistent with what Net::Telnet expects. Having looked at the source code, "-max_buffer_length" and "-Max_Buffer_Length" should also work. Or, you could use the method call on the object itself:
in reply to telnet max buffer exceeded
But I would be very surprised if that behaved any differently.
my $obj = Net::Telnet->new( … );
$obj->max_buffer_length( 50*1024*1024 );
It would be helpful to know how you are trying to fetch the input into your script. If you aren't using $obj->get(); maybe you should be. If you're using any sort of line-oriented method, it does seem strange that a remote process could spew many MB of data without ever emitting something that looks like a line termination, but that could happen.
Anyway, if that's what you're dealing with, obj->get() will just give you arbitrary pieces as you call it (and as input becomes available). I presume you know what you're supposed to do with such data, and can figure out how to parse your way through the pieces...