[Nfd-dev] Help needed with debugging duplicate Nonce

[Junxiao Shi]

Hi Ashlesh

As discussed in 20160628 NFD call, packet timing at B is like:
fwB receives Interest from appB with nonceB; this Interest is not forwarded
fwB receives Interest from fwC with nonceC
Interest is forwarded to fwA with nonceC

This exposes a weakness in outgoing Interest pipeline “pick Interest” step: when fwB forwards the Interest, it picks the latest incoming Interest with nonceC, and thus trigger Nack-Duplicate from fwA. If it picks nonceB instead, there wouldn’t be a Nack-Duplicate from fwA.

But another question is: why fwB did not forward the Interest from appB in the first place? This indicates there might be a FIB update during this process.
Can you provide NFD logs to show whether a FIB update occurred? Log level settings should be FibManager=DEBUG, Forwarder=DEBUG.

Yours, Junxiao

> On Jun 28, 2016, at 10:29 AM, Ashlesh Gawande (agawande) <agawande at memphis.edu> wrote:
> 
> Confirmed that this is happening because node b has the same (sync) interest and hence forwards the interest to a resulting in a NACK.
> 
> Ashlesh
> From: Nfd-dev <nfd-dev-bounces at lists.cs.ucla.edu> on behalf of Ashlesh Gawande (agawande) <agawande at memphis.edu>
> Sent: Tuesday, June 28, 2016 10:48:35 AM
> To: Lan Wang (lanwang); Junxiao Shi
> Cc: nfd-dev at lists.cs.ucla.edu
> Subject: Re: [Nfd-dev] Help needed with debugging duplicate Nonce
>  
> Have attached proof for the said observation.
> 
> tmp-localhost_6_27$ grep --color=always 927845950 */ndndump* | sort -t: -k2
> c/ndndump.c-eth0_1.0.0.10.pcap:1467054254.052399 From: 1.0.0.10, To: 1.0.0.9, Tunnel Type: UDP, INTEREST: /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950
> b/ndndump.b-eth1_1.0.0.9.pcap:1467054254.052424 From: 1.0.0.10, To: 1.0.0.9, Tunnel Type: UDP, INTEREST: /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950
> c/ndndump.c-eth1_1.0.0.6.pcap:1467054254.052428 From: 1.0.0.6, To: 1.0.0.5, Tunnel Type: UDP, INTEREST: /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950
> a/ndndump.a-eth1_1.0.0.5.pcap:1467054254.052436 From: 1.0.0.6, To: 1.0.0.5, Tunnel Type: UDP, INTEREST: /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950
> b/ndndump.b-eth0_1.0.0.2.pcap:1467054257.955331 From: 1.0.0.2, To: 1.0.0.1, Tunnel Type: UDP, INTEREST: /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950
> a/ndndump.a-eth0_1.0.0.1.pcap:1467054257.955348 From: 1.0.0.2, To: 1.0.0.1, Tunnel Type: UDP, INTEREST: /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950
> a/ndndump.a-eth0_1.0.0.1.pcap:1467054257.965760 From: 1.0.0.1, To: 1.0.0.2, Tunnel Type: UDP, NACK: Duplicate, /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950
> b/ndndump.b-eth0_1.0.0.2.pcap:1467054257.965760 From: 1.0.0.1, To: 1.0.0.2, Tunnel Type: UDP, NACK: Duplicate, /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950
> 
> 1) c to b
> 2) c to a
> 3) b to a
> 4) a responds with duplicate NACK
> 
> Meanwhile I will also try to test Junxiao's suggestion by forcing communication over TCP and make sure that this is because of local sync expressing the same interest.
> 
> Ashlesh

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