Question about TcpSocketBase::SendDataPacket()

[Sangwook Bae]

Hi, 

I have an question while I digging the TCP (especially, tcp-socket-base.c).

Related to the previous retransmission problem, Does TCP in NS send a packet immediately when the function TcpSocketBase::SendDataPacket() is called?

If not, is there any structure which is queuing the packets before sending the packets.

The root reason of this question is based on the retransmission.

I think that when the sender receive 3 dupack, it should immediately send the dropped packet, but I am not sure whether the NS is implemented in this way.

Sorry for issuing duplicated (or related) question.

Thank you

Sangwook 

[Natale Patriciello]

On 31/08/16 at 11:15pm, Sangwook Bae wrote:
> Hi,
>
> I have an question while I digging the TCP (especially, tcp-socket-base.c).
> Related to the previous retransmission problem, Does TCP in NS send a
> packet immediately when the function TcpSocketBase::SendDataPacket() is
> called?
> If not, is there any structure which is queuing the packets before sending
> the packets.

TcpTxBuffer.

> The root reason of this question is based on the retransmission.
> I think that when the sender receive 3 dupack, it should immediately send
> the dropped packet, but I am not sure whether the NS is implemented in this
> way.

Yes, it is implemented that way (see the other reply)

> Sorry for issuing duplicated (or related) question.
>

No need for being sorry for well-posted questions. Feel free to do them
as much as you need.

OT: With the SACK support the implementation will change a little, if
you have to do work on that level please consider to switch branch.

Nat