I see. The idea of rate limiting the interface was to simulate congestion and resultant packet loss as observed in a real network.
Thanks for that clarification. Cheers! Durga On Fri, Dec 9, 2016 at 7:26 PM, Justin Pettit <[email protected]> wrote: > > > On Dec 8, 2016, at 12:33 AM, durga <[email protected]> wrote: > > > > Hi All, > > > > I have configured a very basic topology in mininet with 2 switches and a > couple of hosts. > > I have configured tc on all the 4 ports of both the switches and set the > tc rate set at 1Mbps. Qdisc is htb. > > > > Now, as I incrementally generate traffic , though I observe drops via > iperf, I fail to observe any drops on ovs portswhen I use 'ovs-ofctl > dump-ports sw' > > > > Am I looking at wrong places are putting things together incorrectly? > > > > Can someone help me understand why I don't notice any drops when using > ovs-ofctl ? > > > > Few logs: > > > > UDP client: > > root@vd-Veriton-M200-A780:~# iperf -c 10.0.0.2 -u -b 10Mbps > > ------------------------------------------------------------ > > Client connecting to 10.0.0.2, UDP port 5001 > > Sending 1470 byte datagrams > > UDP buffer size: 208 KByte (default) > > ------------------------------------------------------------ > > [ 15] local 10.0.0.1 port 53217 connected with 10.0.0.2 port 5001 > > [ ID] Interval Transfer Bandwidth > > [ 15] 0.0-10.0 sec 12.5 MBytes 10.5 Mbits/sec > > [ 15] Sent 8922 datagrams > > [ 15] Server Report: > > [ 15] 0.0-11.5 sec 10.7 MBytes 7.78 Mbits/sec 0.503 ms 1306/ 8921 > (15%) > > [ 15] 0.0-11.5 sec 1 datagrams received out-of-order > > > > > > OVS output: > > > > root@vd-Veriton-M200-A780:~# ovs-ofctl dump-ports s33 > > OFPST_PORT reply (xid=0x2): 3 ports > > port LOCAL: rx pkts=0, bytes=0, drop=5, errs=0, frame=0, over=0, crc=0 > > tx pkts=0, bytes=0, drop=0, errs=0, coll=0 > > port 1: rx pkts=885787, bytes=33619595672, drop=0, errs=0, frame=0, > over=0, crc=0 > > tx pkts=403525, bytes=26653335, drop=0, errs=0, coll=0 > > port 2: rx pkts=403521, bytes=26652615, drop=0, errs=0, frame=0, > over=0, crc=0 > > tx pkts=884488, bytes=33617623003, drop=0, errs=0, coll=0 > > > > > > TC qdsic output: > > > > root@vd-Veriton-M200-A780:~# tc -s -d class show dev s33-eth2 > > class htb 2:1 root prio 0 quantum 100000 rate 8Mbit ceil 8Mbit linklayer > ethernet burst 1600b/1 mpu 0b overhead 0b cburst 1600b/1 mpu 0b overhead 0b > level 0 > > Sent 25232342 bytes 16683 pkt (dropped 1307, overlimits 0 requeues 0) > > rate 0bit 0pps backlog 0b 0p requeues 0 > > lended: 12183 borrowed: 0 giants: 0 > > tokens: 15781 ctokens: 15781 > > The port stats are showing the statistics on the NIC. However, when QoS > is configure on OVS, it's just configuring the tc (traffic control) system > in the kernel. That implements a software-based limiter, so the packets > are being dropped before they hit the NIC. It looks like your tc output is > showing dropped packets. > > --Justin > > > >
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