Re: [ns] Segmentation Fault + AODV

[Ya Xu <yaxu@ISI.EDU>]

what ns version do you use

On Fri, 6 Apr 2001, Felix Ko wrote:

> Hi all!
> 
> I'm having Problems with wireless simulations using AODV, which causes
> segmentation faults, when the scenarios get larger (many nodes/sources
> or
> high traffic)
> 
> I have traced this problem down to the AODV-implementation:
> When a route is set down in AODV::rt_down, the ifqueue is searched for
> any
> packets, which have to be sent over the (now) broken link.
> 
> If the node is the source of this packet from the ifqueue, a new RREQ
> for
> the destination of the packet is sent out (by calling
> sendRequest(dest)).
> 
> Normally it should be guaranteed, that for ANY destination of a packet
> in the ifqueue a corresponding routingtable-entry exists.
> 
> The Problem is the following: The sendRequest-method relies on an
> existing
> routingtable-entry for all destinations, for which it is called (it is
> "assured",
> but this is disabled by compiling it with NDEBUG by default).
> I don't know how, but it sometimes happens, that a destination of a
> packet
> in the ifqueue HASN'T GOT a routingtable-entry, which causes ns2 to
> crash
> with a segmentation fault, because "rtable.rt_lookup(dst)" returns NULL
> and
> any further access to this pointer hangs in midair!
> 
> QUESTION: Is anybody else experiencing this problem or knows, where
> these
> packets come from? I would LOVE to share this problem with ANYBODY!!!
> 
> So long,
> 
> Felix
> 
>