[ndnSIM] How to deal with large topology in ndnSIM

[Alex Afanasyev]

Hi Wei,

If memory is not an issue, than I'm not yet sure what could be the problem.  Can you run it in debugger and check what exactly causes the segfault?

Time-wise, GlobalRoutingHelper is running Dikjstra algorithm N times (where N number of nodes in the system), each time it's takes N*M steps (M=number of edges).  I haven't thoroughly evaluated performance, but it definitely would not be too fast.

If you want to use GlobalRoutingHelper every time caching changes, than that could be a problem.  You may want to design some way to adjust routing without changing/recalculating routes everywhere, but I'm not sure how (and what are you requirements).

---
Alex

On Mar 12, 2013, at 6:38 PM, weiwang <wangwei2012 at ict.ac.cn> wrote:

> 
> It has 8G memory, I think the memory is enough(when it is running, the memory usage is about 30%). 
> I use realistic topology. If I use addroute, how could I get the FIB for each router?
> 
> And I also wonder that during the content store repacement, it will also update FIB, will it takes such a long time like now?
> 
> 
> > -----原始邮件-----
> > 发件人: "Alex Afanasyev" <alexander.afanasyev at ucla.edu>
> > 发送时间: 2013年3月13日 星期三
> > 收件人: "王伟" <wangwei2012 at ict.ac.cn>
> > 抄送: ndnsim at lists.cs.ucla.edu
> > 主题: Re: [ndnSIM] How to deal with large topology in ndnSIM
> > 
> > Hi Wei,
> > 
> > This is a pretty big topology (and ns-3/ndnSIM has a non-trivial memory overhead per node) and I would suspect that SIGSEGV is related to the fact that OS cannot allocate enough memory.
> > 
> > How much memory the computer you're trying to run this simulation has?
> > 
> > GlobalRoutingHelper/Controller is just one "dirty" way to set up routing in simulation.  For such a large topology, you may want to consider using other, more direct methods, to populate FIBs (e.g., using L2Helper::AddRoute).  Are you using some generated topology or some "realistic" topology?
> > 
> > ---
> > Alex
> > 
> > On Mar 11, 2013, at 11:09 PM, 王伟 <wangwei2012 at ict.ac.cn> wrote:
> > 
> > > 
> > > Hi all,
> > > I have a problem, I use the ndnSIM example to run a scenario which has about 280000 nodes and 800000 links,  
> > > it has a SIGSEGV problem when add GlobalRoute to the node (call function ccnxGlobalRoutingHelper.InstallAll() ),
> > > but when I reduce the links to 700000, it works. 
> > > So, is there a limit in the topology?
> > > 
> > > And it takes a so long time(I use ctrl + C to stop it in gdb) for the CalculateRoutes() function to obtain the global route, how
> > > could I deal with this problem?
> > > 
> > > Thanks
> > > weiwang
> > > 
> > > 
> > > --
> > > Wei WANG
> > > 
> > > 
> > > _______________________________________________
> > > ndnSIM mailing list
> > > ndnSIM at lists.cs.ucla.edu
> > > http://www.lists.cs.ucla.edu/mailman/listinfo/ndnsim
> > 
> 
> 
> 
> --
> Wei WANG
> 
> 
>