Speed tag

[John Scott]

Hi,

I am writing a packet tag class to get nodes mobility information. The position works well, but speed does not. Here's a snapshot of my code

TypeId
LocationTag::GetTypeId ()
{
  static TypeId tid = TypeId ("ns3::LocationTag")
    .SetParent<Tag> ()
  ;
  return tid;
}

TypeId
PositionTag::GetTypeId ()
{
  static TypeId tid = TypeId ("ns3::PositionTag")
    .SetParent<LocationTag> ()
  ;
  return tid;
}

const Vector &
PositionTag::GetPosition () const
{
  return m_position; // from MobilityHelper
}

const Vector &
PositionTag::GetSpeed () const
{
  return m_velocity; // from ConstantVelovityHelper
}

And I have the following libraries declared on my header file:

#include "ns3/tag.h"
#include "ns3/vector.h"

However, I am getting the error:

error: ‘m_velocity’ was not declared in this scope

Can you help please?
In the future I would like to add timestamp and direction of movement too.

Thank you!

[John Scott]

I updated my tag class to implement velocity and timestamp. The code compiles, but when I try to run the application it crashes with the following message. This is the GDB output, which didn't help me.

assert failed. cond="m_current + 1 <= m_end", file=./ns3/tag-buffer.h, line=174
terminate called without an active exception


Program received signal SIGABRT, Aborted.
0x00007fffed3f8428 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:54
54 ../sysdeps/unix/sysv/linux/raise.c: No such file or directory

The complete tag files are attached.

My application calls

/*
   * Location Tag
   */
  Ptr<MobilityModel> model = GetNode ()->GetObject<MobilityModel> ();
  Vector position;
  position = model->GetPosition ();
  NS_LOG_INFO ("Sender position is: " << position);
 
  Vector velocity;
  velocity = model->GetVelocity();
  NS_LOG_INFO ("Snder velocity is: " << velocity);
 
  Time timeNow;
  timeNow = Simulator::Now();
  NS_LOG_INFO ("Current time is: " << timeNow);
 
  if (model)
  {
  position = model->GetPosition ();
  velocity = model->GetVelocity ();
  GeoTag tag;
  tag.SetPosition (position);
  tag.SetSpeed (velocity);
  tag.SetTimestamp(timeNow);
  interest->GetPayload()->AddPacketTag (tag);
  NS_LOG_INFO ("Consumer adding tag!");
  }

Could you assist please?

Thank you

[Konstantinos]

Hi John

Your GetSerializedSize() method is inconsistent with how much you write. 

uint32_t

LocationTag::GetSerializedSize() const
{
  return 2 * sizeof (double);
}

This should return the amount of bytes that are to be written/read from the buffer.

You say 2-doubles, but you actually you write 4 doubles and an uint-64!

Regards,

K

[John Scott]

Hi Konstantinos,

Thank you for your reply.
I changed the buffer size to 4, but got an error.

assert failed. cond="tag.GetSerializedSize () <= TagData::MAX_SIZE", file=../src/network/model/packet-tag-list.cc, line=257

terminate called without an active exception

How do I go about solving this issue?

Thank you

On Monday, April 10, 2017 5:14 AM, Konstantinos <dinos.k...@gmail.com> wrote:

Hi John

Your GetSerializedSize() method is inconsistent with how much you write. 

uint32_t

LocationTag::GetSerializedSize() const
{
  return 2 * sizeof (double);
}

This should return the amount of bytes that are to be written/read from the buffer.

You say 2-doubles, but you actually you write 4 doubles and an uint-64!

Regards,

K

On Sunday, April 9, 2017 at 8:50:24 PM UTC+1, John Scott wrote:

I updated my tag class to implement velocity and timestamp. The code compiles, but when I try to run the application it crashes with the following message. This is the GDB output, which didn't help me.

assert failed. cond="m_current + 1 <= m_end", file=./ns3/tag-buffer.h, line=174
terminate called without an active exception


Program received signal SIGABRT, Aborted.
0x00007fffed3f8428 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/rai se.c:54

54 ../sysdeps/unix/sysv/linux/rai se.c: No such file or directory

The complete tag files are attached.

My application calls

/*
   * Location Tag
   */
  Ptr<MobilityModel> model = GetNode ()->GetObject<MobilityModel> ();
  Vector position;
  position = model->GetPosition ();
  NS_LOG_INFO ("Sender position is: " << position);
 
  Vector velocity;
  velocity = model->GetVelocity();
  NS_LOG_INFO ("Snder velocity is: " << velocity);
 
  Time timeNow;
  timeNow = Simulator::Now();
  NS_LOG_INFO ("Current time is: " << timeNow);
 
  if (model)
  {
  position = model->GetPosition ();
  velocity = model->GetVelocity ();
  GeoTag tag;
  tag.SetPosition (position);
  tag.SetSpeed (velocity);
  tag.SetTimestamp(timeNow);

  interest->GetPayload()->AddPac ketTag (tag);

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[Konstantinos]

Hi,

Please upgrade your ns-3 release (to ns-3-dev)

Up to ns-3.26 there is a limit on the packet data you can add.

https://www.nsnam.org/docs/release/3.26/doxygen/group__packet.html#ga809b1012170dc9803b3e1e85543a374c

However, even if you change the buffer size to 4 as you mention, that is still wrong. 

You have 4-doubles plus 4bytes (the 64-bit timestamp).

Further, if you want to share that information with other nodes, the proper/realistic method would be to add it to the packet as payload, not tag. 

Tags are only simulated meta-data, not real data that go over the wire.

Regards,

K

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[John Scott]

Hi Konstantinos,

Thank you. I ended up creating multiple tags, which is working fine.

I'm having trouble to get the information from a tag that comes from the sink node and add to a packet at the source node.

At sink node:

    data->GetPayload ()->AddPacketTag (sinkTag);

At source node: (don't know how to do this)

    m_sourceTag.SetPosition(data->GetPayload()->PeekPacketTag (sinkTag.GetPosition ()));

How can I read the information from one tag and write on the other tag?

Thank you

On Tuesday, April 11, 2017 1:11 PM, Konstantinos <dinos.k...@gmail.com> wrote:

Hi,

Please upgrade your ns-3 release (to ns-3-dev)

Up to ns-3.26 there is a limit on the packet data you can add.

https://www.nsnam.org/docs/release/3.26/doxygen/group__packet.html#ga809b1012170dc9803b3e1e85543a374c

However, even if you change the buffer size to 4 as you mention, that is still wrong. 

You have 4-doubles plus 4bytes (the 64-bit timestamp).

Further, if you want to share that information with other nodes, the proper/realistic method would be to add it to the packet as payload, not tag. 

Tags are only simulated meta-data, not real data that go over the wire.

Regards,

K

On Monday, April 10, 2017 at 5:20:06 PM UTC+1, John Scott wrote:

Hi Konstantinos,

Thank you for your reply.
I changed the buffer size to 4, but got an error.

assert failed. cond="tag.GetSerializedSize () <= TagData::MAX_SIZE", file=../src/network/model/ packet-tag-list.cc, line=257

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[John Scott]

just solved the issue!

[Konstantinos]

Hi John,

The documentation explains how to Add/Remove PacketTags 

https://www.nsnam.org/docs/models/html/packets.html#adding-and-removing-tags

I would recommend not to do the 'peek' within the set method.

Do all the initialisations, get the values you want and then set it.

Regards

K

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