Re: [multipathtcp] Number of DSS to store

[Christoph Paasch <[e-mail]>]

Hi Anumita & Alan,

On Tuesday 31 July 2012 21:44:35 Anumita Biswas wrote:
> A DSS option may not be sent with corresponding data if there isn't  enough
> tcp option space available such as due to the presence of SACK blocks.

Then the number of SACK-blocks could get reduced for the packet that needs to 
hold the DSS-option, or the SACK-blocks can be on a separate subflow-ack.

SACK-blocks don't necessarily need to be sent reliably. However, the DSS-
option has to be sent reliably. That's why it is good to couple it together 
with the data as delivery is thus guaranteed.


Alan, in your slides yesterday you said:
"A mapping for subflow seqno x MUST not be 
sent before the mappings for subflow seqno 
0 .. x-1 have been sent."

This will still force receivers to be able to store an uncertain number of 
DSS-mappings.

I believe we should say:
"A mapping, covering the subflow seqno's x to y MUST be sent on one of these 
segments."

That way the receiver only has to store one single DSS-mapping option per 
subflow.


Cheers,
Christoph

-- 
IP Networking Lab --- http://inl.info.ucl.ac.be
MultiPath TCP in the Linux Kernel --- http://mptcp.info.ucl.ac.be
Université Catholique de Louvain
--