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Re: [ippm] draft-ietf-ippm-duplicate
Al,
Also as promised in Prague, here are the latest definitions
of Duplicate and Replicated packet outcomes and parameters
from the draft revision of Y.1540.
Thanks.
*5.5.8.3 duplicate IP packet outcome*: A duplicate packet transfer outcome
is a subset of successful packet outcomes, and occurs when a single IP
packet reference event at a permissible ingress MP_0 results in two or more
corresponding reference event(s) on at least one permissible egress MP_i, and
the binary information fields of all the output packets are identical to the
original packet.
This looks fine (and the same to what I defined).
> *5.5.8.4 replicated IP packet outcome*: A replicated packet transfer outcome
> occurs when a single IP packet reference event at a permissible ingress MP_0
> results in two or more corresponding reference event(s) on at least one
> permissible egress MP_i , and the binary information fields of all the output
> packets are identical to the original packet.
This looks fine too, but as far as I can see, it is exactly the same
as for a duplicate IP packet outcome.
And then, for DIPPO:
> The egress reference event at MP_i for a duplicate packet
occurs subsequently to at least one other corresponding egress reference
event for the original packet (usually also at MP_i ).
I can understand this too, it seems to say that the DIPPO occurs after
the first copy arrived. That makes sense. But then for RIPPO:
The egress reference event at MP_i for a replicated packet is the first for
the original packet and occurs prior to at least one other egress reference
event for a duplicate packet (usually also at MP_i ).
This seems to say that the RIPPO occurs before the reference event. But
how can one tell? A packet is sent and received, how can the receiver
tell that a second copy will arrive until that copy actually arrives?
But then what is the difference w.r.t. DIPPO: in both cases 1 packet
is sent and 2 copies arrive. (And the first copy is presumably used
by the recipient, anything else doesn't make sense).
Or is there another subtle difference between DIPPO and RIPPO that I've
missed?
Henk
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