Re: [multipathtcp] Multipath TCP Address advertisement 2/5 - Reliability

[Christoph Paasch <[e-mail]>]

> On Aug 3, 2016, at 8:47 AM, Fabien Duchêne <[e-mail]> wrote:
> 
> Hello,
> 
> As agreed in Berlin during IETF96, I'm sending a series of emails to
> discuss the different contributions proposed
> inhttps://datatracker.ietf.org/doc/draft-duchene-mptcp-add-addr/
> 
> This is the part 2/5 : reliability.
> 
> In RFC6824, ADD_ADDR options can be attached to segments carrying data
> or pure acknowledgements.
> In practice, notably given the length of ADD_ADDR with IPv6 addresses
> and the HMAC, it is very likely that they will be often sent as pure
> acknowledgements.
> This implies that ADD_ADDR are sent unreliably, which could be
> problematic when the ADD_ADDR is required to allow the establishment of
> additional subflows, as in load balancing scenarios. 
> We propose to rely on the "E" (Echo) flag in the ADD_ADDR option.
> This echo flag is used to acknolwedge a received ADD_ADDR by echoing it.
> If the acknowledgement is not received, the ADD_ADDR option will be
> retransmitted up to N times.

I support the addition of the E-flag. Especially, as it improves reliability if one chooses to do the load-balancer deployment as described.


Christoph

> 
> Fabien
> 
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