[ndnSIM] How to get a node's neighbour

[Alex Afanasyev]

Hi Pan,

Let me ask you one clarification question.  What is the intended use of getting the node for the requested item? If it is to collect content store performance, then I would recommend to use content store trace helper (http://ndnsim.net/metric.html#example-of-content-store-trace-helper) or a modified version of this trace helper.

Normally, Node is not directly accessible from lru_policy_traits, as these traits define a general replacement policy.  If you really need it, you can write a specialized policy that has access to node, similar but not exactly as freshness-policy.h and lifetime-stats-policy.h.  If needed, I can try to give you some more examples.  Would you mind giving a high-level idea what you want to implement, so I can give a better suggestion?

---
Alex

On Mar 11, 2013, at 8:24 AM, panhgshine at 163.com wrote:

> Hi Alex,
> 
> Thank you very much! 
> You let me understand much better to the problem.
> By the way, how can I get the request node.
> In cache replacement policy, such as: lru_policy_traits, freshness_policy_traits, I don't know how to get which node request the *item data. Can you help me? And my thoughts is wrong or not?
> 
> Thank you!
> 
> Pan 
> 
> 
> 
> 
> At 2013-03-11 02:33:22,"Alex Afanasyev" <alexander.afanasyev at ucla.edu> wrote:
> >Hi Pan,
> >
> >In general, as in real system, you would need to implement some kind of a resource discovery protocol to discover all node's neighbors.  At the same time, in NS-3, since it is a simulation, it is technically possible to "discover" neighbors directly:
> >
> >In NS-3 in general, you would enumerate all NetDevice's on a particular Node object (http://www.nsnam.org/doxygen/classns3_1_1_node.html):
> >
> >for (uint32_t deviceId = 0; deviceId < node->GetNDevices (); deviceId ++)
> >{
> >    Ptr<NetDevice> device = node->GetDevice (deviceId);
> >
> >    # get channel, to which device is connected (a "wire")
> >    Ptr<Channel> channel = device->GetChannel ();
> >
> >    for (uint32_t channelDeviceId = 0; channelDeviceId < channel->GetNDevices (); channelDeviceId ++)
> >    {
> >        Ptr<NetDevice> channelDevice = channel->GetDevice (channelDeviceId);
> >        if (channelDevice == device)
> >            continue;
> >
> >        # channelDevice is a "neighbor"
> >    }
> >}
> >
> >---
> >Alex
> >
> >On Mar 10, 2013, at 5:53 AM, panhgshine at 163.com wrote:
> >
> >> Hi All,
> >> 
> >> I'm a beginner of NS3 and ndnSIM. Recently, I have read the cache replacement policy code.
> >> Now, I want to get a node's all neighbour. 
> >> Is there anyone can give me some advice or hint?
> >> 
> >> Thank you in advance.
> >> 
> >> Pan