[Ns-developers] turning nodes on/off - failure/recovery models

[Nils Aschenbruck]

Hi all,

> Or do you mean that
> you would want all internal state to be shut down (e.g. routing
> protocols, applications) and restarted later?

Yes, this would be nice. I think this will be necessary for a "switch on with
reset", if you want to reuse existing nodes.
However, as Pavel pointed out, it may be impossible to realize.

Best
Nils


Tom Henderson wrote on 03/31/2010 08:38 AM:
> On 3/30/10 10:07 AM, Lalith Suresh wrote:
>> Hello,
>>
>> On Tue, Mar 30, 2010 at 9:59 PM, Nils Aschenbruck<
>> aschenbruck at cs.uni-bonn.de>  wrote:
>>
>>> Hi all,
>>>
>>> it would be great if ns-3 could support switching on/off nodes.
>>>
>>> There are at least two reasons:
>>> i) in reality this may happen
>>> ii) one of the core characteristics of MANETs it is to be able to
>>> deal with
>>> nodes leaving and (re-)joining the network
>>>
>>> Thus, I think it would be great, if ns-3 could support this.
>>> A node that is switched off should of course not send any messages on
>>> any
>>> layer. In general, this would mean introducing node or device
>>> failure/recovery
>>> models to ns-3.
>>>
>>> If it is supported I think it would be a nice-to-have to support it with
>>> and
>>> without node reset. There may be scenarios where one wants to simulate a
>>> fixed
>>> number of nodes that are switched on and off. But there may also be
>>> scenarios
>>> where one wants to simulate that some nodes leave and other nodes do
>>> later
>>> join
>>> the network. If "switch on with reset" would also be supported, one
>>> could
>>> use
>>> the same nodes that were switched off before in the latter case.
>>>
>>> Thanks for your work on ns-3,
>>> best
>>> Nils
>>>
>>
>>
>> I believe that it is possible to turn a node's network interfaces 'up'
>> and
>> 'down'. So, won't turning all interfaces down be equivalent to a node
>> being
>> switched off and not taking part in the network?
> 
> The IPv4 or IPv6 interface can be set up or down.  This object sits
> above the network device object in the ns-3 stack.  In general, there is
> no "up" or "down" for the NetDevice.  So, setting an IPv4 interface to
> down would allow the device to still communicate at layer-2 (e.g.
> beaconing).
> 
> Regarding Nils's overall request, this capability has been requested in
> the past, and I'm at least partial to adding the capability to set
> NetDevices up and down.  Maybe setting a node to down would be some type
> of helper function that set all devices to down.  Or do you mean that
> you would want all internal state to be shut down (e.g. routing
> protocols, applications) and restarted later?
> 
> Tom
>