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<p>Hi all</p>
<p><br>
</p>
<p></p>
<div>I was running a simple three node topology in Mini-NDN (no experiment, simply: sudo minindn topology_file):<br>
<br>
a<br>
/ \<br>
10 / \ 10<br>
/ \<br>
b----------c<br>
10<br>
<br>
a-eth0 (1.0.0.1)-b-eth0(1.0.0.2)<br>
a-eth1(1.0.0.5)-c-eth0(1.0.0.6)<br>
b-eth1(1.0.0.9)-c-eth1(1.0.0.10)<br>
<br>
I have attached the topology file used.<br>
<br>
ndn-cxx commit: <span>67cb75c7d8a61981cf21581702c955cc7d170642</span><br>
NFD commit: <span>891f47bcfad45885408d1956657be5612620a12d</span><br>
NLSR commit: <span>af909fcc138ce18bd433edecc248ed2b60fc9737</span><br>
ndn-tools commit: <span>d2300731edd88593290ac0c33ed25d5b353b6634</span><br>
<br>
I started tcpdump before NLSR starts on each node and then grepped for NACKs (all of them are duplicate NACKs).<br>
<br>
Then I followed a particular Nonce (at random) to see how the duplicate NACK was generated:<br>
<br>
Tcpdumps are attached in pcap format.<br>
I just used ndndump -r to dump them to ndndump* files and grepped:<br>
<br>
<div>tmp$ grep --color=always 355693607 ndndump.* | sort -t: -k2<br>
ndndump.c-eth1_1.0.0.6:1467048841.203507 From: 1.0.0.6, To: 1.0.0.5, Tunnel Type: UDP, INTEREST: /ndn/NLSR/sync/d34157d84d19a4f39c359c9794b2686cc061a7dc2411a44255c50a173c1cc89e?ndn.MustBeFresh=1&ndn.Nonce=355693607<br>
ndndump.a-eth1_1.0.0.5:1467048841.203512 From: 1.0.0.6, To: 1.0.0.5, Tunnel Type: UDP, INTEREST: /ndn/NLSR/sync/d34157d84d19a4f39c359c9794b2686cc061a7dc2411a44255c50a173c1cc89e?ndn.MustBeFresh=1&ndn.Nonce=355693607<br>
ndndump.c-eth0_1.0.0.10:1467048841.203513 From: 1.0.0.10, To: 1.0.0.9, Tunnel Type: UDP, INTEREST: /ndn/NLSR/sync/d34157d84d19a4f39c359c9794b2686cc061a7dc2411a44255c50a173c1cc89e?ndn.MustBeFresh=1&ndn.Nonce=355693607<br>
ndndump.b-eth1_1.0.0.9:1467048841.203514 From: 1.0.0.10, To: 1.0.0.9, Tunnel Type: UDP, INTEREST: /ndn/NLSR/sync/d34157d84d19a4f39c359c9794b2686cc061a7dc2411a44255c50a173c1cc89e?ndn.MustBeFresh=1&ndn.Nonce=355693607<br>
ndndump.b-eth0_1.0.0.2:1467048841.213733 From: 1.0.0.2, To: 1.0.0.1, Tunnel Type: UDP, INTEREST: /ndn/NLSR/sync/d34157d84d19a4f39c359c9794b2686cc061a7dc2411a44255c50a173c1cc89e?ndn.MustBeFresh=1&ndn.Nonce=355693607<br>
ndndump.a-eth0_1.0.0.1:1467048841.213740 From: 1.0.0.2, To: 1.0.0.1, Tunnel Type: UDP, INTEREST: /ndn/NLSR/sync/d34157d84d19a4f39c359c9794b2686cc061a7dc2411a44255c50a173c1cc89e?ndn.MustBeFresh=1&ndn.Nonce=355693607<br>
ndndump.a-eth0_1.0.0.1:1467048841.214191 From: 1.0.0.1, To: 1.0.0.2, Tunnel Type: UDP, INTEREST: /ndn/NLSR/sync/d34157d84d19a4f39c359c9794b2686cc061a7dc2411a44255c50a173c1cc89e?ndn.MustBeFresh=1&ndn.Nonce=355693607<br>
ndndump.b-eth0_1.0.0.2:1467048841.214191 From: 1.0.0.1, To: 1.0.0.2, Tunnel Type: UDP, INTEREST: /ndn/NLSR/sync/d34157d84d19a4f39c359c9794b2686cc061a7dc2411a44255c50a173c1cc89e?ndn.MustBeFresh=1&ndn.Nonce=355693607<br>
ndndump.a-eth0_1.0.0.1:1467048841.224056 From: 1.0.0.1, To: 1.0.0.2, Tunnel Type: UDP, NACK: Duplicate, /ndn/NLSR/sync/d34157d84d19a4f39c359c9794b2686cc061a7dc2411a44255c50a173c1cc89e?ndn.MustBeFresh=1&ndn.Nonce=355693607<br>
ndndump.b-eth0_1.0.0.2:1467048841.224078 From: 1.0.0.1, To: 1.0.0.2, Tunnel Type: UDP, NACK: Duplicate, /ndn/NLSR/sync/d34157d84d19a4f39c359c9794b2686cc061a7dc2411a44255c50a173c1cc89e?ndn.MustBeFresh=1&ndn.Nonce=355693607<br>
ndndump.a-eth0_1.0.0.1:1467048841.224360 From: 1.0.0.2, To: 1.0.0.1, Tunnel Type: UDP, NACK: Duplicate, /ndn/NLSR/sync/d34157d84d19a4f39c359c9794b2686cc061a7dc2411a44255c50a173c1cc89e?ndn.MustBeFresh=1&ndn.Nonce=355693607<br>
ndndump.b-eth0_1.0.0.2:1467048841.224360 From: 1.0.0.2, To: 1.0.0.1, Tunnel Type: UDP, NACK: Duplicate, /ndn/NLSR/sync/d34157d84d19a4f39c359c9794b2686cc061a7dc2411a44255c50a173c1cc89e?ndn.MustBeFresh=1&ndn.Nonce=355693607<br>
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<br>
Seems like:<br>
1) c sends interest to a<br>
2) c sends same interest to b<br>
3) b sends same interest to a<br>
4) a sends same interest to b<br>
5) a sends NACK [Duplicate] to b<br>
6) b sends NACK [Duplicate] to a<br>
<br>
Strategy is set as follows by NLSR:<br>
<div>mininet> a nfd-status -s<br>
Strategy choices:<br>
/ strategy=/localhost/nfd/strategy/best-route/%FD%04<br>
<b> /ndn/NLSR/sync strategy=/localhost/nfd/strategy/multicast/%FD%01</b><br>
/localhost strategy=/localhost/nfd/strategy/multicast/%FD%01<br>
/ndn/broadcast strategy=/localhost/nfd/strategy/multicast/%FD%01<br>
/ndn/NLSR/LSA strategy=/localhost/nfd/strategy/multicast/%FD%01<br>
/ndn/broadcast/KEYS strategy=/localhost/nfd/strategy/multicast/%FD%01<br>
/localhost/nfd strategy=/localhost/nfd/strategy/best-route/%FD%04<br>
</div>
<br>
<span>So are these duplicate NACKs expected behavior?<br>
</span><br>
Thanks<br>
Ashlesh<br>
<br>
</div>
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