[Nfd-dev] What link object to use on testbed?

[Junxiao Shi]

Hi Haitao

Link object in Interest has been replaced by forwarding hint. However, your
question still applies when forwarding hint is used.


> I tried to send an Interest with link object to the testbed, but the
> producer didn't receive the interest. Could you help to see what is wrong
> with my link object?
>

> Here is what I did:
> (1) The producer registers prefix /org/openmhealth/<user-id> on ucla
> router (spurs.cs.ucla.edu)
> (2) A consumer connecting to remap router (128.97.98.7) sends an interest
> with prefix /org/openmhealth/<user-id>, and with link object. The link
> object has name  /org/openmhealth/<user-id>, and a delegation /ndn/edu/ucla(it
> is ucla router's routable prefix), and it is signed by a cert
> /org/openmhealth/KEY/<user-id>/...., which is signed by ndnfit trust
> anchor, a second trust anchor on the testbed.
>
>
REMAP router is configured <
https://github.com/WU-ARL/NDN_Ansible/blob/138020756db384222e62802baeaca0b6a090c6d7/host_vars/REMAP>
to have network region name /ndn/edu/ucla/remap. Since the delegation name
/ndn/edu/ucla carried in the forwarding hint is a prefix of this network
region name, forwarding hint (or Link object) is removed when it arrives at
REMAP, and forwarding follows the FIB entry for /org/openmhealth/<user-id>.

REMAP has a static route for /org/openmhealth toward udp4://128.97.98.8:6363
at cost 0 with child inherit enabled (as observed on the node right now,
but no evidence in Ansible). If I can assume you are working on the same
app as
http://www.lists.cs.ucla.edu/pipermail/nfd-dev/2017-August/002601.html ,
your prefix registration on UCLA sets route origin to "app", which does not
trigger readvertising to global routing system. Therefore, NFD at REMAP
forwards the Interest to udp4://128.97.98.8:6363 and it does reach your end
host.

Should you set route origin to "client" when you register
/org/openmhealth/<user-id> on UCLA, the route would be readvertised into
the global routing system, and show up at REMAP (and every other router) as
a route with capture flag so that a FIB lookup would not match the udp4://
128.97.98.8:6363 route, and therefore the Interest would go to your end
host. In this case, it would be unnecessary to place a forwarding hint on
the Interest given the route for /org/openmhealth/<user-id> is already
announced globally.

Yours, Junxiao
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