[Nfd-dev] about draft-irtf-icnrg-IPOC

[Lixia Zhang]

Hi Susmit,

thanks a lot for helping out with the specifics regarding the motivations and designs behind IPOC internet-draft that we discussed last Friday.
To answer the question you asked at the end about which way I’d like to get my comments back to all the authors: my worry about going to ICNRG is that I might not be able to keep up with discussions there:(
(students and I went thru all email about IPOC this time because it’s just a one-time obligation)

Wonder if you could help pass the following to your coauthors:

1/ I strongly suggest to avoid abusing interest packets to carry actual payload, IP packets in your design.

a) an interest is meant to retrieve a data packet, that’s why it hangs on PIT at every hop until the data packet comes back (or otherwise timeout).
Buffering lots IP packet in the PIT is *bad*, as it takes space and totally useless.  Data packet in CS can be useful even for one-one communication: in case the packet lost, retransmitted interest will get it from the CS just before the loss point.

b) signed interest is meant to authenticate interest that causes state changes, not for payload authentication.

2/ if one must use NDN to carry IP packets, let’s treat each IP packet as a data packet in both directions, instead of just one direction.

You may ask: how to “push” a received IP packet -- may try a combination of a few ways:
each end could try to fetch *opportunistically*; this could be pretty effective if one can make use of recognized patterns in IP packet arrivals, and the opportunistic fetching interest have a not-too-short lifetime.
in case needed, send a probe interest to trigger the other end sending an interest; this probe interest could have a very short lifetime as it’s not meant to wait for data. This is still a lot better than buffering IP packets in PIT.
Yes there could be a bit delay but look, even in your current design, the IPOC gateway has to wait for Interest form IPOC client already.
The main drawback is doubling packet count, but perhaps not much increase on router memory consumption since
- interest packets are small in size;
- using real data packets to carry IP packets is probably more economical in byte count as compared to abusing interests to carry IP packets.

Doing things in the right way would have a better potential to attract others to your work, I believe.

Just my 2 cents,
Lixia
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