Hi Jonathan
I have serious issues with the use of RPL Instance as the domain for SRH.
>>[R Cragie]
>> p7: RPL Instance ID - why is this needed for source routing? RPL is not even
>> used for source routing. This flavors the SRH unnecessarily and the
>> processing does not use it. If the reason is for checking entering and
>> exiting a RPL domain, this processing needs to be stated.
>[J Hui]
>Page 12 describes processing rules intended to keep the SRH within a RPL
>Instance.
Page 12 has no mention of RPL Instance. Page 13 does mention RPL Instance in
the following rules:
2. Datagrams destined elsewhere within the same RPL Instance are
forwarded to the correct interface.
3. Datagrams destined to nodes outside the RPL Instance are dropped
if the outer-most IPv6 header contains a SRH not generated by the
RPL router forwarding the datagram.
My question is how does a router know whether the next hop is within the same
RPL Instance or not? A router has no idea what RPL Instances its neighbors
belong to.
It seems that a router, that receives a packet with a SRH, does not need to
check if it belongs to the RPL Instance mentioned in the SRH. It just needs to
check if the next hop belongs to that RPL Instance or not. And as I said in the
prev para, I am not sure how would the router make that check.
It would be a problem if the router were required to check its own membership
in the RPL Instance in order to accept a packet with SRH. Routers part of a
source route should not need to maintain any state about it.
Thanks
Mukul
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