[Click] Packet loss with PollDevice

[Yu Chen]

A correction: User 1 and User 2 are sending to each other, User 3 and User 4
are sending to each other.

Besides, I also tried to use one flow, given the default txqueuelen=1000. 
There are also random losses.

The Click version is 1.8.0 on Linux 2.6.24.7.
On Thu, Jan 19, 2012 at 01:45:00PM -0500, Yu Chen wrote:
> Hi all,
> 
> I am having an experiment with the following topology running on Deterlab. I 
> am having a 4-core Xeon and modified e1000 driver running ore Xeon and modified 
> e1000 driver running. The memory is 4GB.
>                      
> 		     User1
>                        |
> 	   User3-----Router------User4		
>                        |
> 	             User2
> 
> User 1 is sending packet to User 2; User 3 is sending packets to User 4. 
> The router only routes stuff with best effort. However, what I observed is 
> very few losses, distributed on a small random set of rounds. What is 
> surprising is that there are losses on one particular netcard when the sending 
> rate is only 125,000 packets/second. The loss happens at the receiving phase.
> 
> Below is what I have tried:
> 1' I am using 4 threads, each corresponding to one pair of PollDevice and 
> ToDevice. 
> 2' I have changed the queue length at the interface cards. I set txqueuelen=1 
> for the senders to decrease the possible burstiness. By increasing the 
> receiving queue length from 64 to 4096
> (the maximum queue length), the loss rate decreases.
> 3' I tried to discard the packets on their arrival at the router. In this case, 
> there is no observed loss.
> 
> I am kind of lost at the point. Any suggestions on what can be the possible 
> reason and what I can try next?
> 
> Attached is my code.
> 
> Best Regards,
> Yu 
> 
> Router:
> ----------------------------------------------------------------------- 
> ddressInfo(router1-w1      10.0.1.1      00:15:17:5d:16:4a,      //eth2
> user1-w1        10.0.1.2      00:15:17:5d:29:28,      //eth0
> router1-w2      10.0.2.1      00:15:17:5d:16:48,      //eth0
> user2-w2        10.0.2.2      00:15:17:57:ce:14,      //eth0
> router1-w3      10.0.3.1      00:15:17:5d:16:4b,      //eth3
> user3-w3        10.0.3.2      00:15:17:5d:27:e8,      //eth0
> router1-w4      10.0.4.1      00:15:17:5d:16:49,      //eth1
> user4-w4        10.0.4.2      00:15:17:5d:2a:3c,      //eth0
> );
> 
> c1 :: Classifier(12/0806 20/0001,
>                  12/0806 20/0002,
>                  12/0800,
>                  -);
> c2 :: Classifier(12/0806 20/0001,
>                  12/0806 20/0002,
>                  12/0800,
>                  -);
> c3 :: Classifier(12/0806 20/0001,
>                  12/0806 20/0002,
>                  12/0800,
>                  -);
> c4 :: Classifier(12/0806 20/0001,
>                  12/0806 20/0002,
>                  12/0800,
>                  -);
> 
> q0 :: Discard;
> // Idle -> ToDevice(eth1);
> // Idle -> ToDevice(eth3);
> // Idle -> ToDevice(eth2);
> // Idle -> ToDevice(eth0);
> q1 :: CPUQueue(1000000) -> EtherEncap(0x0800, router1-w1, user1-w1) -> td1 :: ToDevice(eth2);
> q2 :: CPUQueue(1000000) -> EtherEncap(0x0800, router1-w2, user2-w2) -> td3 :: ToDevice(eth0);
> q3 :: CPUQueue(1000000) -> EtherEncap(0x0800, router1-w3, user3-w3) -> td2 :: ToDevice(eth3);
> q4 :: CPUQueue(1000000) -> EtherEncap(0x0800, router1-w4, user4-w4) -> td0 :: ToDevice(eth1);
> 
> rt :: LookupIPRouteMP(10.0.1.0/32 0, 10.0.1.1/32 0, 10.0.1.255/32 0,
>                      10.0.2.0/32 0, 10.0.2.1/32 0, 10.0.2.255/32 0,
>                      10.0.3.0/32 0, 10.0.3.1/32 0, 10.0.3.255/32 0,
>                      10.0.4.0/32 0, 10.0.4.1/32 0, 10.0.4.255/32 0,
>                      10.0.1.0/24 1, 10.0.2.0/24 2, 10.0.3.0/24 3,
>                      10.0.4.0/24 4, 0.0.0.0/0 0);
> rt[0] -> Discard;
> rt[1] -> q1;
> rt[2] -> q2;
> rt[3] -> q3;
> rt[4] -> q4;
> 
> pd1 :: PollDevice(eth2) -> c1;
> c1[0] -> q0;
> c1[1] -> q0;
> c1[2] -> DropBroadcasts -> Strip(14) -> GetIPAddress(16) -> rt;
> c1[3] -> Discard;
> 
> pd3 :: PollDevice(eth0) -> c2;
> c2[0] -> q0;
> c2[1] -> q0;
> c2[2] -> DropBroadcasts -> Strip(14) -> GetIPAddress(16) -> rt;
> c2[3] -> Discard;
> 
> pd2 :: PollDevice(eth3) -> c3;
> c3[0] -> q0;
> c3[1] -> q0;
> c3[2] -> DropBroadcasts -> Strip(14) -> GetIPAddress(16) -> rt;
> c3[3] -> Discard;
> 
> pd0 :: PollDevice(eth1) -> c4;
> c4[0] -> q0;
> c4[1] -> q0;
> c4[2] -> DropBroadcasts -> Strip(14) -> GetIPAddress(16) -> rt;
> c4[3] -> Discard;
> 
> StaticThreadSched(pd2 0, td0 0, pd0 1, td2 1, pd3 2, td1 2, pd1 3, td3 3);
> 
> User:
> //
> AddressInfo(router1-w1      10.0.1.1      00:15:17:5d:16:4a,      //eth2
> user1-w1        10.0.1.2      00:15:17:5d:29:28,      //eth0
> router1-w2      10.0.2.1      00:15:17:5d:16:48,      //eth0
> user2-w2        10.0.2.2      00:15:17:57:ce:14,      //eth0
> router1-w3      10.0.3.1      00:15:17:5d:16:4b,      //eth3
> user3-w3        10.0.3.2      00:15:17:5d:27:e8,      //eth0
> router1-w4      10.0.4.1      00:15:17:5d:16:49,      //eth1
> user4-w4        10.0.4.2      00:15:17:5d:2a:3c,      //eth0
> );
> //Send
> udp :: FastUDPSource(RATE 400000, LIMIT 20000000, LENGTH 78,
> 		     SRCETH user1-w1, SRCIP user1-w1, SPORT 1,
> 		     DSTETH router1-w1, DSTIP user2-w2, DPORT 1,
> 		     CHECKSUM false, INTERVAL 0, ACTIVE false)
> 	-> ToDevice(eth0);
> 
> s :: Script(TYPE ACTIVE, write ctr.reset, write udp.active false, 
> 	    wait 1, wait 9, write udp.active true);
> 
>