[ns] JoBS example code erroe in the ns Manual

[Lei Liang]

Dear all,
  I am a newbie using NS2. I looked through the section of JoBS in the NS
manual, which I think is the most clear section I found in the manual. in
the section 7.5.2 Configuratoin, you kindly provide some code
for initial setup and creating the JoBS links. However, when i was trying
to study it, i found the NS gives the error warning as bellow for a line
of "set l [$ns get-link $router(1) $router(2)]":

get-node-id-by-addr:Cannot find node with given address
    while executing
"error "get-node-id-by-addr:Cannot find node with given address""
    (procedure "_o3" line 10)
    (Simulator get-node-id-by-addr line 10)
    invoked from within
"$self get-node-id-by-addr $addr"
    (procedure "_o3" line 4)
    (Simulator get-link line 4)
    invoked from within
"$ns get-link $router(1) $router(2)"
    invoked from within
"set l [$ns get-link $router(1) $router(2)]"
    (file "exampleJoBS.tcl" line 39)

I can't see any problem in this line. Could you help me out of this
trouble, please? I will really appreciate your help.
thanks a lot.
cheers,
lei