Re: Simplified REAP description

[Iljitsch van Beijnum <iljitsch@muada.com>]

On 27-okt-2005, at 18:44, Erik Nordmark wrote:

> Receiving a packet with iseeyou=yes
> -----------------------------------

> If this is a "payload reception report", then it is just a FBD  
> keepalive and
> is handled as any shim6 control packet above (resetting timers).

> If it is an "event reception report", it indicates that we can  
> terminate the
> explore phase.
> If the host has not yet sent a "iseeyou=yes" event report, it needs to
> send one in response to this packet.

Now suppose:

A1 ----> B1  (data)
A1 <---- B1  (data)
A1 ---|  B1  (data, failure)
             (timeout)
A1 <---- B1  (icu=0)
A1 ---|  B1  (icu=1)
A2 <---- B1  (icu=1, B hasn't timed out from the last message by A)
A1 ----> B2  (icu=1)

Both now think that the other end can see them but this isn't  
necessarily true because the icu=1 doesn't necessarily apply to the  
last packet sent by the other side. For instance:

A1 ----> B1  (data)
A1 <---- B1  (data)
A1 ---|  B1  (data, failure)
             (timeout)
A1 <---- B1  (icu=0)
A1 ---|  B1  (icu=1)
A2 <---- B1  (icu=0)
A1 ----> B2  (icu=1)
A2  |--- B1  (icu=1, random packet loss on otherwise working link)
A2 ---|  B2  (icu=1, ingress filtering)
A2 <---- B2  (icu=1)

A will now think that A2->B2 works, which isn't true.