Re: Idea for packet numbers

[Jana Iyengar <[e-mail]>]

(Going back to the original discussion)

Magnus,

IIUC, you are asking for a network device to be able to observe packets
within a flow.  don't understand what the value of encrypting the high
order bits is if there are enough low order bits to allow linkability
across packets within a flow. After all, the point of encyptimg packet
number is to avoid linkability, isn't it?

- jana

On Jul 20, 2017 3:00 AM, "Magnus Westerlund" <[e-mail]>
wrote:

> Hi,
>
> There has been some discussion around packet numbers. For passive
> detection of packet loss in measurements and network management, it would
> be really good if the packet numbers where continuous and not only
> monotonically increasing. As this enables one to determine losses upstream
> of the measurement point. At the same time I understand there are benefits
> with being able to introduce gaps into the packet number to test the
> receiver's behaviour.
>
> To enable both of these capabilities I would propose that the N least
> significant bits of the packet number are strictly increased by one. Then
> one can introduce gaps in the bits above the N ones. Yes, that will burn
> through the packet number space faster as the gaps may become larger than
> was the case without this. However, I don't see that this will have
> significant effect unless the sender introduce gaps very frequently so that
> the length of the packet number field needs to be much larger due to the
> outstanding sequence number space is much larger.
>
> The value of N can clearly be discussed but it should be selected so that
> reordering and common burst durations are shorter than the time to wrap the
> strictly increase amount of bits. If the higher bits are available to
> measurement node, some possibility to infer gaps will also be possible. It
> might be that N needs to be scaled with throughput with a minimal value.
> N=8 would mean 256 packets between wraps. I think that is a reasonable
> minimal value. However, that will wrap in 28 ms at 100 mbps of payload
> (assuming 1400 bytes of payload per packet).
>
> So what people think about this idea?
>
>
> Cheers
>
> Magnus Westerlund
>
> ----------------------------------------------------------------------
> Media Technologies, Ericsson Research
> ----------------------------------------------------------------------
> Ericsson AB                 | Phone  [phone]
> Torshamnsgatan 23           | Mobile [phone]
> SE-164 80 Stockholm, Sweden | mailto: [e-mail]
> ----------------------------------------------------------------------
>
>
>