Hopefully you mean version 3.3.6 . ( Version 3.3.3 will not work.)
By mistake g++ version 4.1.2 is used for this, please edit the four Makefile.in
to avoid g++ 4.1.2 being used.
And after that, also edit the four Makefile .
I.e. in otcl-1.0a8/, tclcl-1.0b12/, ns-2.1b9a/, nam-1.0a11a/ .
( There may not yet be a Makefile in nam, Makefile.in will do the trick.)
The export command is temporary, will reset, if you close the terminal.
( export CC=gcc-3.3.6 CXX=g++-3.3.6 && sh install )
The export command usually works for all new ns2, like ns-allinone-2.34,
but for ns-allinone-2.1b9a-gcc32 : I don't know.
The editing of the Makefile** is the proof method.
No issues either with Fedora 13, 14 or Ubuntu 9.04.
( Your first thread, ns-allinone-2.1b9a, says 'Ubuntu 9.04'.)